66 results on '"Stephen L. Webb"'
Search Results
2. Feasibility and application of using Texas horned lizard scat to predict lizard size and age class
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Javier O. Huerta, Scott E. Henke, David B. Wester, Cord B. Eversole, Stephen L. Webb, and Fidel Hernandez
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General Medicine - Published
- 2023
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3. Genomic tools reveal complex social organization of an invasive large mammal (Sus scrofa)
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Chelsea L. Titus, Courtney F. Bowden, Timothy J. Smyser, Stephen L. Webb, and James C. Beasley
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Ecology ,Ecology, Evolution, Behavior and Systematics - Published
- 2022
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4. Analyzing Contacts and Behavior from High Frequency Tracking Data Using the wildlifeDI R Package
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Kenneth L. Gee, Stephen L. Webb, Jed A. Long, and Seth M. Harju
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0106 biological sciences ,R package ,Geography ,010604 marine biology & hydrobiology ,Geography, Planning and Development ,Tracking data ,010603 evolutionary biology ,01 natural sciences ,Simulation ,Earth-Surface Processes - Published
- 2021
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5. Compatibility of Dual Enterprises for Cattle and Deer in North America: A Quantitative Review
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Timothy E. Fulbright, David G. Hewitt, Thomas W. Boutton, Stephen L. Webb, Alfonso Ortega-S., and Stacy L. Hines
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Ecology ,biology ,business.industry ,Wildlife ,Management, Monitoring, Policy and Law ,Odocoileus ,biology.organism_classification ,Geography ,Ecoregion ,Stocking ,Habitat ,Grazing ,Animal Science and Zoology ,Livestock ,Rangeland ,business ,Nature and Landscape Conservation - Abstract
Grazing by livestock, particularly cattle (Bos spp.), is the dominant land use across North American rangelands and often co-occurs in habitats used by wildlife. Deer (Odocoileus spp.) are an ecologically and economically important native wildlife species in North America. Sustainable management and profitable economic returns require an understanding of the factors driving cattle-deer compatibility. Cattle are compatible with deer when cattle grazing does not negatively impact deer or their habitat requirements (food, cover, and space). We reviewed 2,685 publications on cattle-deer interactions across North American ecosystems to assess the compatibility of these two important genera. We extracted data from 85 of the publications, years ranged from 1930–2015, that met criteria for quantifying cattle-deer diet overlap, and cattle effects on deer food, cover, and space. We determined that cattle-deer compatibility across North American ecosystems is dictated: mostly by geographic region; followed by cattle stocking rate and season; and marginally by soil texture. Cattle and deer were compatible across North American ecosystems when cattle stocking rate was less than 0.12−0.17 AUY ha−1. Cattle-deer diet overlap was lowest during summer and autumn. Although, cattle had the greatest potential to decrease forbs in the northeastern forested ecoregion on clay soils during autumn. Cattle had little measurable effect on habitat variables important to deer in open North American ecoregions dominated by herbaceous vegetation. In contrast to rangelands, cattle had the greatest potential to adversely impact deer food, cover, and use of space in forest-dominated ecoregions in North America. However, observations in eastern forested ecoregions only represented 6−16% our data sets. Our review reveals a range of conservative cattle stocking rates (0.12−0.17 AUY ha−1) that will have minimal impact on deer using rangelands, and that stocking rates in forested ecoregions may need to be reduced further to minimize impacts to deer and their habitat requirements.
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- 2021
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6. 85 Automated Walk-Over Weighing System: Methods to Track Daily Body Mass and Growth in Grazing Steers
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Ira L Parsons, Brandi B Karisch, Stephen L Webb, Mike Proctor, Amanda E E Stone, and Garrett M Street
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Genetics ,Animal Science and Zoology ,General Medicine ,Food Science - Abstract
Body weight (BW) is a critical component for monitoring animal weight gain, body condition, nutritional status. Remote animal weighing systems facilitate frequent collection of animal BW, however, datasets often contain spurious data. The objective of this study was to describe the utility of using a remote Walk-over-Weigh system and subsequent methods for data cleaning. Beef steers (n = 10) were tagged with Electronic RFID tags (EID) in an improved pasture (~12.1 hectares) containing Bermuda and Tall Fescue and inter-seeded with Annual Ryegrass and grazed from Feb. – Dec. 2020. Static chute weights (n = 80) were collected monthly, and a WOW system placed by the water to remotely collect BW (n = 5,466). Data were first loaded into Program R and scanned for spurious data using each of 2 primary approaches, 1) the whole herd and individual means ± 1 standard deviation (SD) calculated daily or over the entire trial and 2) each of 3 data smoothing algorithms, which included a quadratic growth model, cubic splines, and polynomial regression. Then, data with spurious observations removed were paired with static chute weights and fitted to a linear model to measure accuracy (mean bias) and precision (R2) of WOW data. Whole herd mean ± 1SD and individual daily mean ± 1SD identified 1,204 and 1,516 spurious data, with mean bias of -12.46 and -15.37 KG and R2 of 0.90 and 0.68, respectively. Smoothing functions identified 1,707, 4,684, and 4,776 spurious points, with a mean bias of 13.61, -19.78, and 12.58 KG, and R2 of 0.94, 0.70, and 0.87 for quadratic growth models, cubic splines, and polynomial regression, respectively. These results indicate the utility of using a simple WOW system to collect data for measuring growth curves and using weight data in a real-time fashion to make management and marketing decisions.
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- 2022
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7. Aiming for the Optimum: Examining Complex Relationships Between Sampling Regime, Sampling Density and Landscape Complexity to Accurately Model Resource Availability
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Stephen L. Webb, Kristine O. Evans, Garrett M. Street, Durham A Norman, Brandi B. Karisch, Ira L Parsons, Melanie R. Boudreau, and A.E. Stone
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Resource (biology) ,business.industry ,Computer science ,Environmental resource management ,Sampling (statistics) ,Sampling density ,business ,Landscape complexity - Abstract
Context Obtaining accurate maps of landscape features often requires intensive spatial sampling and interpolation. The data required to generate reliable interpolated maps varies with spatial scale and landscape heterogeneity. However, there has been no rigorous examination of sampling density relative to landscape characteristics and interpolation methods.ObjectivesOur objective was to characterize the 3-way relationship among sampling density, interpolation method, and landscape heterogeneity on interpolation accuracy in simulated and in situ landscapes. MethodsWe simulated landscapes of variable heterogeneity and sampled at increasing densities using both systematic and random strategies. We applied each of three local interpolation methods: Inverse Distance Weighting, Universal Kriging, and Nearest Neighbor — to the sampled data and estimated accuracy (R2) between interpolated surfaces and the original surface. Finally, we applied these analyses to in situ data, using a normalized difference vegetation index raster collected from pasture with various resolutions.Results All interpolation methods and sampling strategies resulted in similar accuracy; however, low heterogeneity yielded the highest R2 values at high sampling densities. In situ results showed that Universal Kriging performed best with systematic sampling, and inverse distance weighting with random sampling. Heterogeneity decreased with resolution, which increased accuracy of all interpolation methods. Landscape heterogeneity had the greatest effect on accuracy.ConclusionsHeterogeneity of the original landscape is the most significant factor in determining the accuracy of interpolated maps. There is a need to create structured tools to aid in determining sampling design most appropriate for interpolation methods across landscapes of various heterogeneity.
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- 2021
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8. Author response for 'Isotopic analysis reveals landscape patterns in the diet of a subsidized predator, the common raven'
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Seth M. Harju, Chad V. Olson, Stephen L. Webb, and Jenn Hess
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Geography ,Ecology ,Common raven ,Predator ,Isotope analysis - Published
- 2021
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9. Prevalence of
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Katelyn M, Haydett, Steven T, Peper, Cynthia, Reinoso Webb, Hannah S, Tiffin, Alexander N, Wilson-Fallon, Yava L, Jones-Hall, Stephen L, Webb, and Steven M, Presley
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livestock ,disease ,cattle ,parasitic diseases ,parasite ,wild pig ,Article ,canine neosporosis ,invasive species - Abstract
Simple Summary Neospora caninum causes abortion and other reproductive challenges in livestock and leads to large economic losses every year. Wild pigs were evaluated for their potential role in the transmission of N. caninum, the parasite that causes neosporosis in cattle and other animals. Three assays were used to identify past or current exposure to N. caninum in wild pigs and histology was performed to determine if there was a pathology consistent with a N. caninum infection in the tissues that were evaluated. The following assays reported positive results: Kit A—67.8%, Kit B—12.5%, Indirect Fluorescent Antibody Test—84.1%, and Histology—0%. Importantly, the assays used in this study were not congruent with all duplicate samples or between test types and demonstrate the need for a more reliable test to identify N. caninum infections in wild pigs to better assess their potential role in disease transmission. Abstract Neospora caninum is a protozoan parasite, reported as a leading cause of cattle abortions and reproductive failure worldwide, costing the cattle industry approximately $1.3 billion annually. With wild pig (Sus scrofa) populations estimated at over six million in the United States, contact between wild pigs and livestock is inevitable, mainly because of the widespread geographic co-occurrence of the two species. As a known reservoir for numerous fungal, bacterial, viral and parasitic diseases, wild pigs are of particular importance for human and veterinary health relative to the prevention of infectious diseases. The seroprevalence of N. caninum in wild pig populations was previously documented in the United States, raising the question as to their exposure point of prevalence. This research screened 116 individual wild pigs for N. caninum using a variety of available assays. Using two different commercially available ELISA test kits, seroprevalence ranged from 12.5% to 67.8%. The Indirect Fluorescent Antibody Test resulted in our highest percent seroprevalence for these samples, at 84.1%. However, none of our samples showed any presence of N. caninum or associated pathologies via histological evaluation of representative tissues. Importantly, the assays used in this study were not congruent with all duplicate samples or between the test types used. The implications of these non-congruent results demonstrates that currently available testing assays produce variable results, underscoring the need for more reliable testing kits and a standardized methodology when assessing disease prevalence in wildlife, particularly for N. caninum in wild pigs, which impacts prevalence and comparability across studies.
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- 2021
10. Land use and dispersal influence mortality in white‐tailed deer
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Bronson K. Strickland, Jacob M. Haus, Jacob L. Bowman, Stephen L. Webb, and Joseph E. Rogerson
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White (horse) ,Ecology ,Land use ,Public land ,General Earth and Planetary Sciences ,Biological dispersal ,Biology ,Ecology, Evolution, Behavior and Systematics ,Nature and Landscape Conservation ,General Environmental Science - Published
- 2019
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11. PSII-12 Identifying behaviors and the ‘normal’ daily ethogram using accelerometers on grazing animals
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Ira L Parsons, Durham A Norman, Cassidy C Catrett, A.E. Stone, Brandi B. Karisch, Garrett M. Street, Stephen L. Webb, and Jane E. Dentinger
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Poster Presentations ,Ethogram ,Animal science ,Grazing ,Genetics ,Animal Science and Zoology ,General Medicine ,Biology ,Accelerometer ,Food Science - Abstract
Animal behavior plays a crucial role as an indicator of animal health and nutritional status and serves as an indicator of animal growth. The objective of this study was to build an ethogram describing behavior in grazing cattle. We collected video and accelerometer data from crossbred steers (n = 10) used as part of a larger grazing study on the HH Leveck Animal Research Center, Mississippi State, MS. Daily Diary accelerometers (Wildbyte® technologies, Swansea) were programmed to collect magnetometer and accelerometer data at 40 Hz and attached to the GPS collars fitted on the animals prior to their release into a 10-hectare pasture of Tall Fescue and Bermudagrass, overseeded with Annual Ryegrass. Automated camera traps (Bushnell Essential®) were synced with UTC time and programmed to record 30-second video clips when triggered. Approximately 387,000 accelerometer signals representing 161 minutes of behavior from 10 animals were recorded, and behavior classified according to 1 of 5 categories: traveling, foraging, resting, ruminating, and grooming (Kilgour et al., 2012). Categorized accelerometer data was used to train a random forest model (Liaw and Weiner, 2002) in Program R (R Core Team, 2020), which resulted in a model sensitivity of 0.97, 0.93, 0.90, 0.87, and 0.80 for Traveling, Foraging, Resting, Ruminating, and Grooming, respectively, and an overall model accuracy of 0.95. Behaviors were aggregated into behavior bouts, and a daily ethogram was calculated for March 2019. This revealed that the steers spent the most amount of time traveling, an average of 1,026 minutes per day. This behavior was followed, in the average length of time, by foraging and resting for 205 ± 52.8 minutes and 31.8 ± 28.2 minutes per day, respectively. These results indicate the ability to accurately build a behavioral ethogram for grazing cattle and warrant further study in future research and livestock management.
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- 2021
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12. 175 GPS Tracking Collars and Accelerometers Provide Detailed Tracking of Foraging Behavior and Space Use in Grazing Steers in Bermudagrass and Tall Fescue Pasture
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Garrett M. Street, Brandi B. Karisch, Ira L Parsons, Jane E. Dentinger, Durham A Norman, Stephen L. Webb, Cassidy C Catrett, and A.E. Stone
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geography ,geography.geographical_feature_category ,business.industry ,Foraging ,Space use ,General Medicine ,Accelerometer ,Tracking (particle physics) ,Pasture ,Grazing ,Oral Presentations ,Genetics ,Global Positioning System ,Environmental science ,Animal Science and Zoology ,business ,Food Science ,Remote sensing - Abstract
Previous research in feedlot studies has demonstrated that cattle feeding behavior is driven by internal metabolic processes and external environmental stimuli and serves as an indicator of animal health, nutritional status, and growth and feed quality and availability. However, technology has only recently allowed measurement of foraging behavior in grazing cattle. Objectives of this study were to measure frequency and duration of foraging bouts, meals, and total distance traveled during meals in grazing steers. The study was conducted as part of a larger grazing study on a 10-hectare Bermudagrass and Tall Fescue pasture, overseeded with Annual Ryegrass, located at the HH Leveck Animal Research Center, Mississippi State, MS. Using tri-axial accelerometers and GPS information from 10 crossbred steers, we examined foraging and meal bout frequency and duration and distance and speed traveled per meal for the period of March 2019. Observed animal behavior was used to train a randomforest model to predict foraging behavior, with model accuracy and sensitivity of 0.95 and 0.93, respectively. We found individual foraging bouts occurred on average 2,849 bouts per day and took on average 5.0 ± 1.8 min (range: 3–9 min), and that steers fed on average 205 ± 52.8 min/day (range: 120–270 min/day). Steers had an average of 9.5 ± 2.9 meals/day, that took on average, 89.3 ± 93.9 min/meal (range: 0.5–938.5 min/meal). Steers traveled an average of 412.4 ± 93.9 meters per meal, with an average foraging speed between 0 and 0.63 m/s. Traveling distance while foraging was positively correlated with meal length (0.83, P < 0.01) and foraging speed (0.70, P < 0.01). These results show that cattle grazing behavior can be accurately quantified in grazing cattle and warrants further research to examine associations between animal efficiency and performance, forage quality, and pasture management.
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- 2021
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13. Conservation Forensics: The Intersection of Wildlife Crime, Forensics, and Conservation
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Aaron M. Haines, Stephen L. Webb, and John R. Wallace
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Wildlife trade ,Government revenue ,Biodiversity ,Law enforcement ,Wildlife ,Poaching ,Crime science ,Business ,Commercialization ,Environmental planning - Abstract
Poaching and the illegal wildlife trade (i.e., wildlife crime) are a multibillion-dollar global industry. The commercialization and overexploitation of wildlife caused by wildlife crime threaten biodiversity, particularly many of the species already on the cusp of extinction. Wildlife crime also leads to ecosystem collapse and loss of government revenues and threatens the strength and economic aspiration of developing nations. Efforts from wildlife law enforcement to prevent wildlife crime are a conservation necessity. The purpose of this chapter is to introduce the field of conservation forensics. Conservation forensics is an applied field of conservation crime science that fits within the broader frameworks of green and conservation criminology. This field of study applies hard science techniques used to gather wildlife crime data such as genetics, chemical analysis, geographical analysis, statistics, artificial intelligence, and computational modeling toward techniques that can directly benefit the efforts of law enforcement personnel involved in protecting imperiled wildlife. This chapter identifies and reviews tools and techniques that can help achieve the goals of conservation forensics: the prosecution of wildlife criminals and the prevention of wildlife crime to conserve biodiversity.
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- 2021
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14. Individual heterogeneity in resource selection has implications for mortality risk in white‐tailed deer
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Jacob L. Bowman, Kyle P. McCarthy, Stephen L. Webb, Joseph E. Rogerson, Jacob M. Haus, and Bronson K. Strickland
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White (horse) ,Resource (biology) ,hunting ,Ecology ,Individual heterogeneity ,Multilevel model ,habitat selection ,individual heterogeneity ,Delaware ,Geography ,lcsh:QH540-549.5 ,lcsh:Ecology ,multilevel modeling ,Odocoileus virginianus ,Ecology, Evolution, Behavior and Systematics ,Selection (genetic algorithm) ,Demography - Abstract
Individual animals vary in their selection of habitat as a function of sex, age, and experience. Such individual heterogeneity is important when decomposing segments of the population that may or may not respond to habitat or population management, or when targeting management that has greater potential for increasing demographic responses (e.g., survival). We examined individual heterogeneity in habitat selection during the hunting season using multilevel step selection models for 59 adult (≥2.5 yr old) white‐tailed deer (Odocoileus virginianus) of both sexes. We used fractal analysis to determine the scale at which animals perceived and responded to the landscape, and modeled selection using covariates for use of agriculture, wetland, edge, forest interior, and distance to road. We tested for differences in individual‐specific habitat selection between age classes and modeled survival as a function of individual‐specific selection using proportional hazard modeling. At the population level, males selected for agriculture and forest interior and avoided roads, while adult females selected for agriculture. Individual‐specific selection of forest interior differed between age classes in males, with mature males selecting interior forest less frequently than immature males. Risk of mortality was related negatively to individual‐specific selection for wetland areas in males and forest interior for females. No habitat variables that were selected for or avoided at the population level influenced mortality risk at the individual level, suggesting management efforts based on traditional population‐level analysis may be misguided. Managers attempting to influence population dynamics via habitat and harvest management should be aware of the substantial heterogeneity in habitat selection among individual animals before implementing costly practices that may not be effective for their objectives.
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- 2020
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15. Sampling Theory: For the Ecological and Natural Resource Sciences. David G.Hankin, Michael S.Mohr, and Kenneth B.Newman. 2019. Oxford University Press, Oxford, United Kingdom. 368 pp. $55.00 paperback. ISBN: 978‐0‐19‐881580‐8
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Stephen L. Webb
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Kingdom ,Ecology ,Anthropology ,General Earth and Planetary Sciences ,Sociology ,Natural resource ,Ecology, Evolution, Behavior and Systematics ,Nature and Landscape Conservation ,General Environmental Science ,Sampling theory - Published
- 2021
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16. Prevalence of Neospora caninum Exposure in Wild Pigs (Sus scrofa) from Oklahoma with Implications of Testing Method on Detection
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Cynthia Reinoso Webb, Yava L. Jones-Hall, Steven T. Peper, Stephen L. Webb, Alexander N. Wilson-Fallon, Steven M. Presley, Katelyn M. Haydett, and Hannah S. Tiffin
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Veterinary medicine ,Prevalence ,Wildlife ,Disease ,canine neosporosis ,invasive species ,SF600-1100 ,parasitic diseases ,Seroprevalence ,Parasite hosting ,Direct fluorescent antibody ,disease ,General Veterinary ,biology ,business.industry ,wild pig ,biology.organism_classification ,Neospora caninum ,livestock ,QL1-991 ,cattle ,parasite ,Animal Science and Zoology ,Livestock ,business ,Zoology - Abstract
Neospora caninum is a protozoan parasite, reported as a leading cause of cattle abortions and reproductive failure worldwide, costing the cattle industry approximately $1.3 billion annually. With wild pig (Sus scrofa) populations estimated at over six million in the United States, contact between wild pigs and livestock is inevitable, mainly because of the widespread geographic co-occurrence of the two species. As a known reservoir for numerous fungal, bacterial, viral and parasitic diseases, wild pigs are of particular importance for human and veterinary health relative to the prevention of infectious diseases. The seroprevalence of N. caninum in wild pig populations was previously documented in the United States, raising the question as to their exposure point of prevalence. This research screened 116 individual wild pigs for N. caninum using a variety of available assays. Using two different commercially available ELISA test kits, seroprevalence ranged from 12.5% to 67.8%. The Indirect Fluorescent Antibody Test resulted in our highest percent seroprevalence for these samples, at 84.1%. However, none of our samples showed any presence of N. caninum or associated pathologies via histological evaluation of representative tissues. Importantly, the assays used in this study were not congruent with all duplicate samples or between the test types used. The implications of these non-congruent results demonstrates that currently available testing assays produce variable results, underscoring the need for more reliable testing kits and a standardized methodology when assessing disease prevalence in wildlife, particularly for N. caninum in wild pigs, which impacts prevalence and comparability across studies.
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- 2021
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17. An Editor's Guide to Writing and Publishing Science. MichaelHochberg. 2019. Oxford University Press, Oxford, United Kingdom. 253 pp. $35.95 paperback. ISBN: 978‐0‐19‐880479‐6
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Stephen L. Webb
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Kingdom ,Ecology ,Publishing ,business.industry ,media_common.quotation_subject ,General Earth and Planetary Sciences ,Art ,business ,Ecology, Evolution, Behavior and Systematics ,Classics ,Nature and Landscape Conservation ,General Environmental Science ,media_common - Published
- 2020
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18. Principles for Management of Fisheries and Wildlife: The Manager as Decision‐maker. LarkinPowell. 2020. Cognella Academic Publishing, San Diego, California, USA. 464 pp. $138.95 paperback. ISBN: 978‐1‐5165‐2403‐7
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Stephen L. Webb
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Ecology ,Publishing ,business.industry ,Political science ,Wildlife ,General Earth and Planetary Sciences ,business ,Decision maker ,Ecology, Evolution, Behavior and Systematics ,Nature and Landscape Conservation ,General Environmental Science ,Management - Published
- 2020
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19. Genetic Consequences of Fence Confinement in a Population of White-Tailed Deer
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Rodney L. Honeycutt, Randy W. DeYoung, Ryan Toby, Kenneth L. Gee, Emily K. Latch, Stephen Demarais, Robert A. Gonzales, and Stephen L. Webb
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fence ecology ,microsatellite ,Population ,Wildlife ,inbreeding ,Biology ,Fencing ,Gene flow ,Genetic drift ,Wildlife management ,education ,lcsh:QH301-705.5 ,Nature and Landscape Conservation ,education.field_of_study ,Genetic diversity ,Ecology ,Ecological Modeling ,conservation ,high tensile electric fence ,genetic diversity ,Agricultural and Biological Sciences (miscellaneous) ,lcsh:Biology (General) ,Odocoileus virginianus ,gene flow ,human activities ,Inbreeding ,management - Abstract
Fencing wildlife populations can aid wildlife management goals, but potential benefits may not always outweigh costs of confinement. Population isolation can erode genetic diversity and lead to the accumulation of inbreeding, reducing viability and limiting adaptive potential. We used microsatellite and mitochondrial DNA data collected from 640 white-tailed deer confined within a 1184 ha fence to quantify changes in genetic diversity and inbreeding over the first 12 years of confinement. Genetic diversity was sustained over the course of the study, remaining comparable to unconfined white-tailed deer populations. Uneroded genetic diversity suggests that genetic drift is mitigated by a low level of gene flow, which supports field observations that the fence is not completely impermeable. In year 9 of the study, we observed an unexpected influx of mtDNA diversity and drop in inbreeding as measured by FIS. A male harvest restriction imposed that year increased male survival, and more diverse mating may have contributed to the inbreeding reduction and temporary genetic diversity boost we observed. These data add to our understanding of the long-term impacts of fences on wildlife, but also highlight the importance of continued monitoring of confined populations.
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- 2021
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20. Hunting intensity alters movement behaviour of white-tailed deer
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Joshua A. Gaskamp, Kenneth L. Gee, Stephen Demarais, Samuel K. Riffell, Stephen L. Webb, and Andrew R. Little
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0106 biological sciences ,biology ,Ecology ,Relative displacement ,Space use ,Oklahoma ,Animal behaviour ,Nocturnal ,Odocoileus ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Predation ,010601 ecology ,Continuous variable ,Hunting season ,Animal science ,Hunting ,Population management ,Global positioning systems ,Odocoileus virginianus ,Ecology, Evolution, Behavior and Systematics - Abstract
Recreational hunters have largely replaced natural predators of white-tailed deer ( Odocoileus virginianus ) across much of North America; thereby, providing the greatest form of risk (both direct and indirect) to survival. On a 1861-ha property in Oklahoma, USA, we evaluated how controlled hunting influenced movement behaviour (using movement rate [m/h] and relative displacement index [%]) of 37 adult (≥2.5 years) male deer at three risk treatment levels (i.e., control = no risk; low-risk = 1 hunter/101 ha; and high-risk = 1 hunter/30 ha), two temporal periods of risk (i.e., diurnal [06:00–18:00] and nocturnal [18:00–06:00]), and across time (36 days); time was modelled as a continuous variable that covered five risk exposure periods (risk present or absent in brackets; i.e., pre-season [absent], scout [present], pre-hunt [absent], hunt [present], and post-hunt [absent]). Movement rate (m/h) decreased over time for all risk treatment levels and temporal period of risks; however, the magnitude (i.e., slope) of decrease varied across treatments. The magnitude of decrease in movement rate was similar for control and low risk treatments during diurnal and nocturnal periods, but was different between low and high risk, and high risk and control treatments. Relative displacement (%) of deer was greatest at the start of the study, decreasing during the study finally resulting in displacement values being three times less after hunting season. Deer responded to the presence of hunters on the landscape by adapting movement strategies both spatially and temporally to avoid potential contact with hunters. During the study, deer reduced movements and used smaller areas more intensively, as indicated by the relative displacement index. Reducing movement or space use may lead to lower detection of deer by hunters, thus increasing the probability of survival through reduced harvest. Understanding deer behavioural responses to hunters (and at different levels of risk) could be used to facilitate or reduce harvest based on population management objectives.
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- 2016
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21. Pseudorabies Virus and Brucella abortus from an Expanding Wild Pig (Sus scrofa) Population in Southern Oklahoma, USA
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Joshua A. Gaskamp, Stephen L. Webb, Kenneth L. Gee, Nova J. Silvy, and Tyler A. Campbell
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0301 basic medicine ,Veterinary medicine ,Swine ,040301 veterinary sciences ,animal diseases ,030106 microbiology ,Population ,Brucella abortus ,Pseudorabies ,Animals, Wild ,Biology ,Brucellosis ,Virus ,0403 veterinary science ,03 medical and health sciences ,medicine ,Animals ,Population Growth ,education ,Ecology, Evolution, Behavior and Systematics ,Swine Diseases ,education.field_of_study ,Ecology ,business.industry ,Oklahoma ,04 agricultural and veterinary sciences ,medicine.disease ,Porcine reproductive and respiratory syndrome virus ,biology.organism_classification ,Herpesvirus 1, Suid ,Virology ,Vaccination ,biology.protein ,Livestock ,Antibody ,business - Abstract
Wild pigs ( Sus scrofa ) are causing increasing ecologic and economic damage at a global scale. Because wild pigs can carry ≥65 diseases that affect livestock, their widespread expansion threatens native wildlife and livestock. We screened wild pigs from south-central Oklahoma, US for antibodies against Brucella abortus , pseudorabies virus (PRV), and porcine reproductive and respiratory syndrome virus (PRRS). These pathogens were chosen because they are part of eradication programs in the US and could have large economic impacts on domestic livestock if transmitted from wild animals. We tested 282 serum samples during spring 2010 (n=149) and 2011 (n=133) and found an overall exposure rate to PRV of 24.1% (n=68); PRV was detected at two of three study sites. Two wild pigs had detectable antibody to B. abortus , and one had detectable antibody to PRRS. On average, 27% of wild pigs within a sounder were positive for PRV antibody, with 44% of the sounders (16/36) having at least one positive individual. These data highlight that wild pigs could carry pathogens that affect domestic livestock. Because the US is free of these pathogens in commercial livestock operations, continued surveillance and vaccination of domestic livestock are needed. Commercial livestock producers at the wildlife-livestock interface may benefit from spatial prioritization of risk zones to facilitate strategic control efforts.
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- 2016
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22. Simulated effects of releasing pen‐raised deer into the wild to alter population‐level antler size
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Christopher G. Mcdonald, Stephen L. Webb, Bronson K. Strickland, Stephen Demarais, and Trent Smith
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0106 biological sciences ,education.field_of_study ,Population level ,biology ,Ecology ,business.industry ,Range (biology) ,Population ,Wildlife ,Odocoileus ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Population control ,Antler ,010601 ecology ,Animal science ,Livestock ,education ,business ,Nature and Landscape Conservation - Abstract
The ability to develop large antlers in penned deer (Odocoileus sp.) has increased interest in releasing pen-raised deer to increase antler size of wild populations. We used a model based on population genetic theory with random removal as the form of population control and either 10% emigration and 10% immigration to represent a free-ranging population (Free Range) or with no egress or ingress to represent a fenced property (Fenced). We compared results with a livestock model with no egress or ingress and selective removal of smaller antlered males as the form of population control (Best Case). We modeled release of fawns with an antler distribution averaging 200 gross Boone and Crockett (BC a 25% replacement increased score by 18. The Best Case Model increased score by 33 at 25% replacement. The cost for each unit increase in score was US$115,000 in a free-ranging population, US$75,000 in a fenced population, and US$33,000 in the best case. Our results suggest that altering genetic composition of white-tailed deer populations is not feasible for free-ranging populations and very costly within fenced populations. © 2016 The Authors. Wildlife Society Bulletin published by Wiley Periodicals, Inc. on behalf of The Wildlife Society.
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- 2016
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23. Surficial soil damage by wild pigs (Sus scrofa) decreases pecan harvest efficiency
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Charles Rohla, W. Sue Fairbanks, Kelly S. Boyer, and Stephen L. Webb
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0106 biological sciences ,Crop ,010602 entomology ,food ,Agronomy ,Carya illinoinensis ,Biology ,01 natural sciences ,Agronomy and Crop Science ,food.food ,010606 plant biology & botany - Abstract
Pecans (Carya illinoinensis) are an economically important specialty crop grown in the southern and southcentral parts of the United States. However, the invasive and exotic wild pig (Sus scrofa) is also distributed over this range, with some of the highest densities occurring in areas of pecan production. Using a before-after control-impact (BACI) study design, we quantified harvest efficiency of pecans in native groves and improved orchards damaged by wild pigs and in control areas that were not damaged. We found that 44% of pecans were not harvested in areas damaged by wild pigs. In control areas, 10% of pecans were not harvested due to the inefficiency of the pecan harvester. Therefore, the loss of pecans attributed to wild pig damage was 34%. This information was used to develop an online calculator ( https://nobleapps.noble.org/agcalculators/calculators/pecanloss ) that estimates production and economic losses, and can be used for making management decisions (e.g., wild pig control, second harvest of pecans, etc.).
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- 2020
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24. Variance components and heritability of biomass yield in switchgrass (Panicum virgatum L.) grown in the Southern Great Plains
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Joseph H. Bouton, Hem S. Bhandari, Brindha Narasimhamoorthy, Stephen L. Webb, Charles R. Yesudas, Qingzhen Jiang, and Malay C. Saha
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Germplasm ,education.field_of_study ,biology ,Ecotype ,Crop yield ,Population ,Soil Science ,Biomass ,Growing season ,Heritability ,biology.organism_classification ,Agronomy ,Panicum virgatum ,education ,Agronomy and Crop Science - Abstract
Switchgrass ( Panicum virgatum L.) is an important feedstock for biofuel production and also used for rangeland restoration and as a forage crop. Wide variability has been observed in switchgrass at both ecotypic and population levels. Variance component analysis can identify the relative contribution of different factors which can be used as guidance in selection of genotypes in breeding programs. The objectives of this study were to estimate and partition the sources of variance components and to estimate heritability of biomass yield in switchgrass. A total of 36 accessions including 31 plant introduction accessions collected from the Germplasm Resources Information Network (GRIN) and five improved populations developed at the Samuel Roberts Noble Foundation were used for estimating the variance components. Fourteen of these were lowland and 22 upland accessions. The accessions and populations were evaluated in Ardmore, Oklahoma from 2007 to 2011. Average biomass yield of lowland accessions was 2.41 ± 0.05 kg plant −1 and that of upland accessions was 0.57 ± 0.01 kg plant −1 . Biomass yield increased up to 526% from 2008 to 2010; however, it decreased up to 88% from 2010 to 2011 growing seasons due to severe drought. Variance component analysis revealed that accessions accounted for 48.5 and 37.2% of the total variation in the lowland and upland ecotypes, respectively. Biomass yield was moderately heritable for switchgrass (0.5) and for lowland (0.6) and upland (0.44) ecotypes, indicating that biomass yield could be improved through selection. In general, lowland ecotypes are more productive; however, a few upland accessions (e.g., PI 476294, PI 657660, PI 642193) were found productive even during dry years, albeit less biomass was produced than lowland ecotype.
- Published
- 2014
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25. Does human predation risk affect harvest susceptibility of white-tailed deer during hunting season?
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Andrew R. Little, Joshua A. Gaskamp, Stephen Demarais, Samuel K. Riffell, Stephen L. Webb, Kenneth L. Gee, and Jerrold L. Belant
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Ungulate ,biology ,Wildlife ,social sciences ,Odocoileus ,Affect (psychology) ,biology.organism_classification ,Predation ,Hunting season ,Animal science ,population characteristics ,Animal behavior ,Population management ,Nature and Landscape Conservation ,Demography - Abstract
Large carnivores are considered a primary source of mortality for many ungulate populations, but harvest by hunters is the primary means of population management. However, research is needed to evaluate how human predation risk influences observability (a surrogate to harvest susceptibility) of ungulates. We determined how hunting intensity and duration influence observation rates of white-tailed deer (Odocoileus virginianus) and how deer behavior (i.e., movement rate and resource selection) affects observation rates. We sampled 37 adult (≥2 yr) male deer at 2 levels of risk (i.e., low-risk = 1 hunter/101 ha; and high-risk = 1 hunter/30 ha) during 3 exposure periods (i.e., first, second, and third weekend of hunting) on a 1,861-ha property in Oklahoma, USA, during the 2008 and 2009 rifle deer-seasons. Observation rates (collared deer/hunter-hr/day) were greatest during the first weekend in both the low- and high-risk treatments, but declined each weekend thereafter in both treatments. Immediately prior to hunter observation, movement rate of observed collared deer was greater than that of unobserved collared deer, but only when hunting risk was high. Greater movement rates of deer in the high-risk treatment also led to a greater probability of observation. Hunters also had a greater probability of observing collared deer at higher elevations. Overall, deer modified their behavior to avoid detection by hunters. These results can be used to explain decreased observation rates to hunters and to modify harvest rates by altering timing and intensity of human predation risk during the recreational hunting season to help achieve population management goals through harvest. © 2014 The Wildlife Society.
- Published
- 2014
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26. Reciprocal Effects for Biomass Yield in Lowland Switchgrass
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Stephen L. Webb, Hem S. Bhandari, Joseph H. Bouton, and Malay C. Saha
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Crop yield ,Maternal effect ,Biomass ,Biology ,medicine.disease_cause ,biology.organism_classification ,Agronomy ,Bioenergy ,Pollen ,medicine ,Panicum virgatum ,Cultivar ,Agronomy and Crop Science ,Hybrid - Abstract
Switchgrass (Panicum virgatum L.) cultivar research is focused on improvement in biomass yield and feedstock composition for bioenergy use. These improvements could be achieved by exploiting additive and non-additive effects of nuclear genes, as well as reciprocal differ- ences. The objective of this study was to evalu- ate the influence of reciprocal effects on bio - mass yield in lowland switchgrass. Forty-six biparental crosses and their reciprocals were evaluated at two locations in south-central Oklahoma using a honeycomb design. The trial was established in the summer of 2007, and year-end biomass yields were recorded during 2008 and 2009. The mean DNA content of the parents ranged from 1.96 to 3.70 pg, confirm - ing that the parental genotypes were tetraploid. Ten of the 46 crosses demonstrating favorable reciprocal effects (P £ 0.10) had >12% biomass yield advantage. The direction of reciprocal dif- ference was fairly consistent across locations by years. The relative advantage of using a cer- tain genotype as the female parent depended on the genetic background of the other geno- type used in crossing, indicating the complex genetics of reciprocal effects. The hybrids from parent 'LL43' in crosses with 'LL126' and 'LL22' produced an average of >40% biomass when used as the pollen parent rather than using it as the female. Evaluation of genotypes of inter- est for reciprocal effects by crossing with sev- eral other genotypes would help identify parents with favorable maternal effects for use in devel- opment of superior synthetic or hybrid varieties.
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- 2014
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27. Ecotypic and genotypic effects on regrowth and heading date in switchgrass (Panicum virgatum)
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Malay C. Saha, Stephen L. Webb, Hem S. Bhandari, Joe Bouton, and Qingzhen Jiang
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Germplasm ,biomass ,Ecology ,Breeding program ,Ecotype ,Perennial plant ,variance components analysis ,Vegetative reproduction ,switchgrass ,Sowing ,regrowth ,Plant Science ,Biology ,vegetative growth period ,biology.organism_classification ,Biochemistry, Genetics and Molecular Biology (miscellaneous) ,heading date ,Agronomy ,Panicum virgatum ,Cultivar ,Ecology, Evolution, Behavior and Systematics ,Original Research - Abstract
Switchgrass (Panicum virgatum L.) is a native perennial grass species with great potential for bioenergy and forage. However, knowledge about its genetics and biology related to breeding is still in its infancy. Studying the diversity of switchgrass germplasm will shed light on variability, response to environmental conditions, adaptability, breeding, etc. Thirty‐six switchgrass accessions/cultivars were used to study the ecotypic and genotypic effects on regrowth, heading date, and vegetative growth period. The R‐360 honeycomb design was used for planting these accessions in 2007. Data on regrowth and heading dates were recorded in 2008, 2010, and 2011. Vegetative growth period was calculated by subtracting the regrowth date from the heading date. It was found that the lowland started regrowing earlier (77 ± 0.4 days of the year, DOY) than the upland ecotype (82 ± 0.3 DOY). The upland had earlier heading date (160 ± 0.4 DOY) than the lowland ecotype (173 ± 0.5 DOY). Vegetative growth period was about 18 days longer in the lowland (89 ± 0.6 days) than the upland ecotype (71 ± 0.4 days). For switchgrass (i.e., all accessions), biomass yield was related positively to growth period and heading date; however, biomass was only weakly related to regrowth. Therefore, when targeting biomass in the breeding program, growth period may be a quick and reliable reference in both ecotypes to quickly estimate biomass potential while regrowth and heading date may be better used as a parameter for accessions within an ecotype.
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- 2019
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28. Spatial Ecology of Female Mule Deer in an Area Proposed for Wind Energy Development
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Matthew R. Dzialak, Karl L. Kosciuch, Jeffrey B. Winstead, Stephen L. Webb, and Dean J. Houchen
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education.field_of_study ,Ecology ,biology ,Population ,Wildlife ,Nocturnal ,Odocoileus ,Snow ,biology.organism_classification ,Crepuscular ,Geography ,Spatial ecology ,education ,Diel vertical migration ,Ecology, Evolution, Behavior and Systematics - Abstract
Development for wind energy is increasing rapidly across the United States, particularly in Wyoming, despite a general lack of information on the potential interaction development could have on wildlife species. Therefore, knowledge of the space use and movement patterns of individuals can help define spatial distributions and management unit boundaries for populations prior to development. Such knowledge can also be used as baseline data from which to assess any future impacts on animal populations. We investigated the spatial ecology of female mule deer (Odocoileus hemionus; n = 18) equipped with global positioning system collars from 23 February 2011 to 15 January 2012 in an area along the Wyoming-Colorado border that has been proposed for wind energy development. The objectives of this study were to collect predevelopment baseline estimates of annual and seasonal home-range and core area size and fidelity, movement between seasonal ranges, changes in the use of elevation, and movement patterns at 2 temporal resolutions (i.e., within-season diel patterns and year-round diurnal and nocturnal movements by week). Annual size of home ranges averaged 2495 ha (SE = 121), whereas size of core areas averaged 310 ha (SE = 30). Seasonal site fidelity was substantial (81.1%, SE = 5.7) between successive cool-season ranges. Migration distances between cool- and warm-season home ranges were minimal (spring migration = 1319 m; autumn migration = 1342 m). Deer exhibited crepuscular movement patterns (peaks near 06:00 and 18:00) during the warm season but showed a diurnal movement pattern dur- ing the cool season (peak from 06:00 to 15:00). Partuition influenced movement during the warm season; movement was much reduced during a period from mid-June to mid-July. Deer in this population appear to be year-round residents that exhibit strong seasonal and annual fidelity to previously established ranges and modify movement patterns in rela- tion to general changes in environmental conditions (e.g., snow). These findings can be used to define seasonally impor- tant ranges and formulate boundaries and sizes of game management units. Understanding fine-scale temporal move- ment allows the development of strategies that could minimize disturbance to deer while allowing for development or recreation.
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- 2013
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29. Accuracy and implications of visually estimating age of male white‐tailed deer using physical characteristics from photographs
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Kenneth L. Gee, John H. Holman, and Stephen L. Webb
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Physical development ,Research use ,Geography ,biology ,Wildlife ,Odocoileus ,biology.organism_classification ,Age specific ,Nature and Landscape Conservation ,Demography - Abstract
Visually estimating age of white-tailed deer (Odocoileus virginianus) using physical characteristics, commonly referred to as “aging on the hoof” (AOTH), has gained in popularity as part of management programs. However, AOTH has not been evaluated in reference to its accuracy or the accuracy of its users; and most importantly, AOTH is an unstandardized method for estimating age. To assess accuracy of AOTH as it currently is applied, we developed an accuracy examination consisting of a series of photographs of 70 wild, known-aged, antlered, male deer from south-central Oklahoma, USA, ranging in age from approximately 1.5 to ≥7.5 years. We distributed a pre-assessment questionnaire and the accuracy examination to registrants from the 2009 annual meeting of the Southeast Deer Study Group and to select individuals known to use AOTH. One hundred six wildlife professionals that commonly used the technique completed the assessment and examination. Overall accuracy averaged 36% when placing deer into year classes (min. = 16%; max. = 56%). Accuracy tended to be greater for younger year-classes (1.5–2.5 yr); accuracy generally declined as age increased. On average, 62%, 43%, 25%, 30%, 25%,15%, and 31% of deer were placed into the correct year-class for the 1.5, 2.5, 3.5, 4.5, 5.5, 6.5, and ≥7.5 year-classes, respectively. We provide the first known accuracy assessment by users of the AOTH technique. It appears that the AOTH technique lacks accuracy for placing deer into specific year-classes, which has implications for selective harvest decisions and research use. Accuracy may be improved by developing standardized protocols and criteria for using the technique and training observers. © 2013 The Authors Wildlife Society Bulletin published by Wiley Periodicals, Inc. on behalf of The Wildlife Society
- Published
- 2013
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30. Estimates of variance components and repeatability for total forage yield in rye: implications for breeding
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Jagadeesh Mosali, Jerry L. Baker, Stephen L. Webb, and Mark A. Newell
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Secale ,biology ,food and beverages ,Forage ,Plant Science ,Repeatability ,biology.organism_classification ,Crop ,Agronomy ,Yield (wine) ,Genetics ,Variance components ,Cultivar ,Agronomy and Crop Science ,Selection (genetic algorithm) - Abstract
Cereal rye (Secale cereale L.) is an important forage crop in the USA for stocker cattle (Bos sp.) production, thus making forage yield an important breeding objective for the crop. However, little information is known about the repeatability for forage yield in this crop. The objectives of this research were to: (i) estimate variance components for forage yield from long-term variety trials, (ii) estimate the repeatability for forage yield and (iii) relate this to breeding strategies for increased forage yield in rye. Trials were conducted over 14 years where 97 USA open-pollinated varieties (OPVs) were evaluated. Repeatability ranged from 0.57 to 0.86 when the data were analysed by year for the 3 years with significant genotype main effects. Possible explanations for the lack of significant genotype main effects are discussed. Practical implications of these findings indicate that the development of improved cultivars with greater forage yield will require improved methods of selection based on family performance rather than the current methods based primarily on single plant visual selection.
- Published
- 2013
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31. Developing spatially‐explicit weighting factors to account for bias associated with missed GPS fixes in resource selection studies
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James P. Mudd, Stephen L. Webb, Jeffrey B. Winstead, and Matthew R. Dzialak
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Discrete choice ,Computer science ,business.industry ,Spatial mapping ,Data loss ,Management, Monitoring, Policy and Law ,Logistic regression ,Weighting ,Censoring (clinical trials) ,Assisted GPS ,Statistics ,Global Positioning System ,business ,Ecology, Evolution, Behavior and Systematics ,Nature and Landscape Conservation - Abstract
Global positioning system (GPS) collars are prone to locational error and missed fixes caused by vegetation and topography, meaning that locational error may be greater, or fix success lower, in certain habitats. These forms of error can lead to bias associated with data loss or censoring. The goals of this paper were to: 1) estimate resource selection functions using logistic regression to map probability of acquisition (Pacq) of a GPS location and subsequent censoring of locational error in relation to landscape features and 2) develop a spatially-explicit map of weighting factors across the landscape to avoid over- or underestimating resource selection. Female mule deer Odocoileus hemionus were used as a case example and to validate maps. Locational error and Pacq were influenced by vegetation and topography, thus necessitating a means to weight the data. Applying logistic regression to quantify Pacq allowed an easy and straightforward approach to mapping Pacq and subsequently, weighting factors (weigh...
- Published
- 2013
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32. Winter Resource Selection by Mule Deer on the Wyoming–Colorado Border Prior to Wind Energy Development
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Stephen L. Webb, Karl L. Kosciuch, Matthew R. Dzialak, and Jeffrey B. Winstead
- Subjects
geography ,geography.geographical_feature_category ,Resource (biology) ,Forage (honey bee) ,Ecology ,biology ,Range (biology) ,Management, Monitoring, Policy and Law ,Odocoileus ,biology.organism_classification ,Shrubland ,Habitat ,Spatial ecology ,Animal Science and Zoology ,Physical geography ,Selection (genetic algorithm) ,Nature and Landscape Conservation - Abstract
Areas identified as winter range are important seasonal habitats for mule deer ( Odocoileus hemionus ) because they can moderate overwinter mortality by providing thermal cover and forage. Therefore, identifying seasonally important resources is a conservation priority, especially when sensitive areas are proposed for development. We used data collected from global positioning system (GPS) collars fitted on female mule deer ( n = 19; one location every 3 h) to identify resources important during winter (23 February 2011–30 April 2011; 1 November 2011–15 January 2012) in a region spanning southern Wyoming and northern Colorado that has been proposed for wind energy development. The study period included portions of two consecutive winters but were pooled for analysis. We used methods to account for GPS biases, fractal analyses to determine perceived spatial scale, and discrete choice models and conditional logistic regression to assess resource selection prior to development (i.e., baseline data). Resource selection by female mule deer revealed similar patterns between active (0600–1800 hours) and nonactive (2100–0300 hours) periods. Deer selected most strongly for proximity to rock outcrops and shrubland and average values of slope. Deer tended to avoid roads and grasslands; all other landscape features had minimal influence on resource selection (hazard ratios near, or overlapping, 1). Using the fixed-effects coefficient estimates, we developed two spatially explicit maps that depicted probability of mule deer occurrence across the landscape. Based on an independent validation sample, each map (active and nonactive) validated well with a greater percentage of locations occurring in the two highest probability of use bins. These maps offer guidance to managing mule deer populations, conserving important seasonal habitats, and mitigating development (e.g., wind energy) in areas identified as important to mule deer.
- Published
- 2013
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33. Ecosystem-level dynamics of soil-vegetation features, with implications for conserving a narrowly endemic reptile
- Author
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John J. Wondzell, Nicholas P. Gould, Jeffrey B. Winstead, Stephen L. Webb, James P. Mudd, Dean J. Houchen, Matthew R. Dzialak, Jennifer E. Hess, and Seth M. Harju
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geography.geographical_feature_category ,Ecology ,biology ,Range (biology) ,Landform ,Geography, Planning and Development ,Vegetation ,Sagebrush lizard ,biology.organism_classification ,Geography ,Habitat ,Ecosystem ,Landscape ecology ,Endemism ,Nature and Landscape Conservation - Abstract
Narrow endemism presents challenges to species occurrence modeling particularly when the distribution of key local habitat features changes across space and time as a function of processes operating at larger scales. One need facing conservation in such settings is a better understanding of the biogeographic dynamics of the larger features that govern occurrence of critical local habitat. The Mescalero–Monahans shinnery sands region of western North America is a dynamic landscape where sand shinnery oak interacts with wind-driven sand to establish dune habitat. This ecosystem supports several narrowly endemic dune-dwelling species including the dunes sagebrush lizard. Using near-anniversary satellite and aerial imagery from 1986, 1998, and 2011, we integrated object-based image classification and statistical analysis to develop and validate a spatially explicit estimate of the sand shinnery oak ecosystem, including dynamics associated with its attrition and emergence, at high resolution throughout an 89,849-km2 study area encompassing the range of the dunes sagebrush lizard. The spatial estimate of the distribution and extent of the sand shinnery oak soil-vegetation association validated reasonably well (overall accuracy = 0.79; sensitivity = 0.49; specificity = 0.91) and showed that the association declined 10.3 % in extent during the 25-year assessment window. The presence of sand shinnery oak, patch size, and patch isolation were dynamic across space and time; a regression model showed that smaller, isolated patches on the periphery of the system were more likely to be lost over time whereas larger, less isolated, and centrally distributed patches were more likely to persist or expand. This study details broadly applicable methods to accurately delineate landforms throughout large extents, and offers mapping tools specific to issues surrounding Mescalero–Monahans shinnery sands endemics that are readily amenable to testing, refinement, and application in efforts to focus sustainable landscape management including conservation of endemic species.
- Published
- 2013
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34. Greater Sage-Grouse and Severe Winter Conditions: Identifying Habitat for Conservation
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Seth M. Harju, Jeffrey B. Winstead, Stephen L. Webb, Larry D. Hayden-Wing, Matthew R. Dzialak, and Chad V. Olson
- Subjects
education.field_of_study ,Resource (biology) ,Ecology ,business.industry ,Population ,Environmental resource management ,Habitat conservation ,Context (language use) ,Management, Monitoring, Policy and Law ,Geography ,Rangeland management ,Habitat ,Sustainability ,Animal Science and Zoology ,education ,business ,Landscape planning ,Nature and Landscape Conservation - Abstract
Developing sustainable rangeland management strategies requires solution-driven research that addresses ecological issues within the context of regionally important socioeconomic concerns. A key sustainability issue in many regions of the world is conserving habitat that buffers animal populations from climatic variability, including seasonal deviation from long-term precipitation or temperature averages, and that can establish an ecological bottleneck by which the landscape-level availability of critical resources becomes limited. We integrated methods to collect landscape-level animal occurrence data during severe winter conditions with estimation and validation of a resource selection function, with the larger goal of developing spatially explicit guidance for rangeland habitat conservation. The investigation involved greater sage-grouse (Centrocercus urophasianus) that occupy a landscape that is undergoing human modification for development of energy resources. We refined spatial predictions by exploring how reductions in the availability of sagebrush (as a consequence of increasing snow depth) may affect patterns of predicted occurrence. Occurrence of sage-grouse reflected landscape-level selection for big sagebrush, taller shrubs, and favorable thermal conditions and avoidance of bare ground and anthropogenic features. Refinement of spatial predictions showed that important severe winter habitat was distributed patchily and was constrained in spatial extent (7–18% of the landscape). The mapping tools we developed offer spatially explicit guidance for planning human activity in ways that are compatible with sustaining habitat that functions disproportionately in population persistence relative to its spatial extent or frequency of use. Increasingly, place-based, quantitative investigations that aim to develop solutions to landscape sustainability issues will be needed to keep pace with human-modification of rangeland and uncertainty associated with global climate change and its effects on animal populations.
- Published
- 2013
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35. Spatially explicit analysis of poaching activity as a conservation management tool
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Stephen L. Webb, Nolan Burke, Lucas K. Wilsing, Michael D. Barske, Aaron M. Haines, Matt Grabe, and David Elledge
- Subjects
geography.geographical_feature_category ,biology ,Ecology ,Wildlife ,Poaching ,Odocoileus ,biology.organism_classification ,Management tool ,Trophy ,Fishery ,Geography ,Explicit analysis ,Spatial variability ,Nature and Landscape Conservation ,Riparian zone - Abstract
Most Americans support legal hunting for food or as a population management tool, but there are strong concerns about illegal hunting activities such as poaching. Poaching may negatively impact animal populations by causing local extinctions, reducing genetic variability, reducing trophy size and hunting opportunities, and altering sex ratios and age structures. One approach to help mitigate poaching is to identify patterns of reported poaching activity and to document poaching arrests to help facilitate the efficiency of future surveillance for poachers. Our goal for this manuscript was to analyze temporal, spatial, and environmental patterns associated with poaching activity reported for white-tailed deer (Odocoileus virginianus) in Fayette County, Iowa, USA, based on reports of poaching activity. We analyzed data from 67 reported poaching events from 2000 to 2009 and correlated these events with temporal, spatial, and environmental variables to determine trends in illegal hunting behavior. We found that poachers preferred to be active during the evening in mid- to late autumn (primarily Oct–Dec), on days with no precipitation and high visibility, and in areas next to roads, forests, and riparian cover types containing variable topography. We used these results to develop a spatially explicit map depicting hotspots of poaching activity. By identifying patterns of poaching behavior and spatially explicit prediction maps, conservation officers will be able to survey for poaching activity more efficiently. © 2012 The Wildlife Society.
- Published
- 2012
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36. Animal Movement: Statistical Models for Telemetry Data. Mevin B.Hooten, Devin S.Johnson, Brett T.McClintock, and Juan M.Morales. 2017. CRC Press, Boca Raton, Florida. 306 pages. $89.95 hardback. ISBN 978-1-4665-8214-9
- Author
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Stephen L. Webb and Garrett M. Street
- Subjects
010601 ecology ,0106 biological sciences ,Ecology ,media_common.quotation_subject ,General Earth and Planetary Sciences ,Art ,01 natural sciences ,Humanities ,Ecology, Evolution, Behavior and Systematics ,Nature and Landscape Conservation ,General Environmental Science ,media_common - Published
- 2017
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37. Effects of selective harvest on antler size in white-tailed deer: A modeling approach
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Bronson K. Strickland, Stephen Demarais, Stephen L. Webb, Kenneth L. Gee, Brian Kinghorn, and Randy W. DeYoung
- Subjects
education.field_of_study ,animal structures ,Ecology ,Reproductive success ,Population size ,Population ,Zoology ,Biology ,Odocoileus ,Heritability ,biology.organism_classification ,Antler ,Genetic model ,General Earth and Planetary Sciences ,education ,Ecology, Evolution, Behavior and Systematics ,Selection (genetic algorithm) ,Nature and Landscape Conservation ,General Environmental Science - Abstract
Selective harvesting in wild deer (Odocoileus spp.) populations is a common practice that may influence antler size. However, in free-ranging populations, response due to selection is unknown or difficult to quantify because antlers are influenced by nutrition and population demographics. We used quantitative genetic models to predict how white-tailed deer (O. virginianus) antlers would respond to selection and what variables (i.e., population size, age structure, mating ratio, and heritability) most affected antler size. We validated our quantitative genetics program by comparing model results with a population of deer used for controlled breeding experiments; modeled antler points (AP) and score increased (2.2–4.3 AP and 48.5–97.7 cm, respectively) after 8 years of selection, similar to observed increases in AP (3.2) and score (92.3 cm) from the controlled population. In modeled free-ranging populations, mating ratio, age structure, and heritability were more important in influencing antler size than size of the population. However, response to selection in free-ranging populations was lower (0.1–0.9 AP) than controlled breeding populations even after 20 years of selection. These results show that selective harvesting of free-ranging white-tailed deer may be inefficient to change population-level genetic characteristics related to antler size. Response of antlers in free-ranging deer will be less than controlled populations, and possibly modeled free-ranging simulations, because individual reproductive success of males is lower, breeding is done by a large group of males, and reproductive and survival rates are lower. These factors, and others, reduce the amount of improvement that can be made to antlers due to selection. Therefore, selective harvesting in free-ranging populations should be justified for managing population demographics and dynamics, but not for changing the genetic characteristics of populations. © 2011 The Wildlife Society.
- Published
- 2011
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38. Effects of human activity on space use and movement patterns of female Elk
- Author
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Matthew R. Dzialak, Larry D. Hayden-Wing, Seth M. Harju, Stephen L. Webb, and Jeffrey B. Winstead
- Subjects
Animal Distribution ,education.field_of_study ,Geography ,Disturbance (ecology) ,Movement (music) ,Ecology ,Home range ,Population ,Elevation ,Wildlife ,Space use ,education ,Nature and Landscape Conservation - Abstract
It is important to consider how human activity might influence behavior (e.g., space use and movement) in animals because such influences could have consequences for animal distribution or population performance. We documented and compared annual space use and daily movement patterns (i.e., movement distance and tortuosity) of female elk (Cervus elaphus) relative to human activity associated with development of energy resources in Colorado and New Mexico, USA, from 2006 to 2010. We analyzed data on 145 female elk fitted with global positioning system collars. While controlling for elevation, slope, and distance to anthropogenic features and vegetative cover, we found that proximity to the gas field generally was associated with smaller home ranges, more complex movement paths (i.e., greater tortuosity) and longer distance moved over a 3-hr period (during most seasons). Comparing elk inside of the gas field to those outside of the gas field revealed differences in space use and movement patterns at varying levels of human activity. These differences likely reflected behavior by which elk in industrial areas attempted to minimize contact with sources of human activity; whereas, elk using both industrial and nonindustrial areas exhibited behavior that could be considered escape strategies (i.e., familiarity and use of large spatial extents, increased movement distance, and linear movement paths) in response to seemingly unpredictable levels of human activity due to their use of multiple areas. Understanding such behavioral responses informs efforts to minimize effects of human activity on animal populations. © 2011 The Wildlife Society.
- Published
- 2011
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39. Design of an underwater telemetry antenna for locating and retrieving submerged radiocollars
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Andrew R. Little, Stephen L. Webb, Stephen Demarais, Kenneth L. Gee, and Joshua A. Gaskamp
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business.industry ,Computer science ,Telemetry ,Global Positioning System ,Antenna (radio) ,Field simulation ,Underwater ,business ,Nature and Landscape Conservation ,Marine engineering - Abstract
Radiocollars represent a significant investment of financial resources, particularly global positioning system (GPS) collars, and loss of data imposes analytical limitations from reduced sample sizes. Radiocollars on large, terrestrial mammals are seldom lost in the water. However, several instances in Oklahoma, USA necessitated a reliable and cost-effective technique for retrieving GPS collars from underwater to salvage the financial investment and data. We designed an underwater telemetry antenna to find and retrieve collars in ≤3 m of water. We describe field simulations under varying environmental and water conditions, and provide a list of materials along with instructions and considerations for building and using an underwater telemetry antenna. We successfully used our underwater antenna to locate and retrieve our submerged collar that was disposed of in a pond after illegal harvest; we also located and retrieved all collars used for field simulation (n = 11). On average, search time for collars was 30 min. The design of our underwater antenna was inexpensive (US$30), easy to build, and effective at locating submerged collars in 0.6–3.0 m of water, with varying water turbidity and substrates. Although our underwater telemetry antenna was designed to meet our needs, it could be modified for more specific or alternative circumstances. © 2011 The Wildlife Society.
- Published
- 2011
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40. The spatial pattern of demographic performance as a component of sustainable landscape management and planning
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Larry D. Hayden-Wing, John J. Wondzell, Matthew R. Dzialak, Seth M. Harju, Jeffrey B. Winstead, Stephen L. Webb, and James P. Mudd
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education.field_of_study ,Ecology ,biology ,business.industry ,Geography, Planning and Development ,Environmental resource management ,Population ,biology.organism_classification ,Geography ,Sustainable management ,Risk of mortality ,Spatial variability ,Landscape ecology ,business ,education ,Landscape planning ,Nature and Landscape Conservation ,Wildlife conservation ,Rocky Mountain elk - Abstract
Prioritizing habitat for animal conservation in heterogeneous landscapes requires an understanding of where animal occurrence coincides with human influences on demographic performance. We related broad-scale patterns of occurrence with risk of mortality among female Rocky Mountain elk (Cervus elaphus) in a human-modified landscape to develop a spatially-explicit framework for animal conservation at the landscape level. Variability in the spatial pattern of elk occurrence was driven by preference for specific habitat types as well as responses to human activity. In contrast, risk of mortality was a function of human modification of the landscape with little variation explained by habitat. Proximity to industrial development was associated with increased risk of mortality whereas proximity to residences and agricultural structures was associated with decreased risk. Individual-level results revealed added complexity, whereby risk of mortality was associated with a consistent pattern of occurrence relative to industrial development, yet the association between risk and occurrence relative to structures was highly variable and likely a function of disparate land-use priorities. Approaches to managing human-mediated risk at the landscape level are most effective when they decompose human activity into constituent parts influencing risk, and when individual variation relative to the population response is investigated. Conservation interventions need to target factors that have a consistent influence across the population rather than risk uncertainty that would arise from targeting factors that influence individuals in variable or situation-specific ways. The spatial tools developed herein provide guidance for sustainable landscape planning in the study area, while the concept of linking occurrence and demographic performance within a hierarchical modeling framework has general application for animal conservation in landscapes subject to change, human-caused or otherwise.
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- 2011
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41. Size of Home Ranges and Movements Determine Size and Configuration of Management Units and Potential Spread of Disease in White-Tailed Deer (Odocoileus virginianus)
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Stephen Demarais, Stephen L. Webb, and David G. Hewitt
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education.field_of_study ,biology ,Animal health ,Ecology ,Population ,Odocoileus ,biology.organism_classification ,Disease control ,Geography ,Disease prevention ,Wildlife management ,education ,Ecology, Evolution, Behavior and Systematics ,Demography ,Wildlife conservation - Abstract
We modeled how variation in size of home ranges and annual movements of white-tailed deer (Odocoileus virginianus) in southern Texas altered ability to manage deer within various sizes of management units and discussed implications for spread of disease. The percentage of adult (≥3.5 years) males remaining on management units varied 98% of males would use management units of 1,000 km2 because their use of space would not result in use of adjoining management units. Migration of deer in northern latitudes resulted in 20% of the population using management units of 1,000 km2, which potentially could expose large areas (>25,000 km2) to disease because a greater percentage of deer would use adjoining management units compared to deer in southern latitudes. Our results are useful in determining...
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- 2010
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42. Size and Fidelity of Home Ranges of Male White-Tailed Deer (Odocoileus virginianus) in Southern Texas
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Stephen Demarais, Stephen L. Webb, M Atthew T. Pollock, Donald G. Whittaker, and R Obert E. Zaiglin
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Geography ,biology ,Forestry ,Odocoileus ,biology.organism_classification ,Ecology, Evolution, Behavior and Systematics - Abstract
We studied size and fidelity of home ranges of adult ($3.5 years) male white-tailed deer (Odocoileus virginianus) during 2 years in southern Texas. Size of core areas, determined using the 50% fixed-kernel method, averaged 86 6 14 ha, whereas size of home ranges, determined using the 95% fixed-kernel method, averaged 403 6 61 ha. Deer shifted centroids of home ranges 363 6 45 m from year 1 to year 2. Overlap in home ranges averaged 66 6 2% between years. These data provide additional support that home ranges of adult male white-tailed deer in southern Texas are relatively small and stable. However, the majority of home ranges are larger than most landholdings. Therefore, development of cooperatives among neighboring landowners may be necessary to effectively manage age structure of males. RESUMEN—Estudiamos el tamano y fidelidad del rango de hogar de machos adultos ($3.5 anos) del venado cola blanca (Odocoileus virginianus) durante dos anos en el sur de Texas. El tamano de las a nucleo, determinado mediante del metodo de %fixed-kernel& al 50%, promedio ´8 66 14 ha, mientras el tamano del rango de hogar, determinado mediante del metodo de %fixed-kernel& al 95%, promedio ´ 403 6 61 ha. Los centroides del rango de hogar cambiaron 363 6 45 m entre el primer y segundo ano. El traslape en rangos de hogar entre anos promedio ´6 66 2%. Estos datos proveen un apoyo adicional de que los rangos de hogar del macho adulto del venado cola blanca en el sur de Texas son relativamente pequenos y estables. Sin embargo, la mayoro ´a de los rangos de hogar son mas grandes que las tierras de los ranchos. Por lo tanto, el desarrollo de cooperativas entre los duenos de ranchos vecinos puede ser necesario para manejar efectivamente la estructura de edad de los machos.
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- 2010
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43. Using Fractal Analyses to Characterize Movement Paths of White-Tailed Deer and Response to Spatial Scale
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Kenneth L. Gee, Samuel K. Riffell, Stephen L. Webb, and Stephen Demarais
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Forage (honey bee) ,Ecology ,biology ,Movement (music) ,Home range ,Foraging ,Zoology ,Odocoileus ,biology.organism_classification ,Fractal dimension ,Habitat ,Genetics ,Spatial ecology ,Animal Science and Zoology ,Ecology, Evolution, Behavior and Systematics ,Nature and Landscape Conservation - Abstract
It is often difficult to test hypotheses about how and why animal movement responds to environmental conditions, and at what spatial scales movement decisions are made, all of which are critical for sound management. We used fractal dimension (D) as a measure of tortuosity because it described animal movement patterns and was useful for testing hypotheses about effects of sex, home-range size, monthly rainfall, and reproductive phase on movement paths and for detecting changes in movement patterns of animals across a range of movement distances. We captured and fitted 33 (18 females and 15 males) white-tailed deer (Odocoileus virginianus) with global positioning system collars. We found that females moved more tortuously (D 5 1.75 6 0.035 SE) than males (D 5 1.549 6 0.025). These differences in movement were related to home-range size of females but not of males. Rainfall predicted D for females; thus, females may have been able to forage more intensively in a smaller area due to increased forage availability. Fractal D of females was greatest during the parturition period (1.468 6 0.02), likely due to restricted movements in smaller areas or increased foraging. Home-range size of males was similar in spring and rut, but D was lower during rut, indicating that deer changed movement patterns within previously established home ranges. Movement patterns were similar at path lengths related to foraging patches and home ranges, whereas movement patterns changed as path length approximated the size of habitat patches.
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- 2009
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44. Survival and fidelity of an enclosed white‐tailed deer population using capture–recapture‐reporting data
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Kenneth L. Gee, Guiming Wang, and Stephen L. Webb
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education.field_of_study ,biology ,Ecology ,media_common.quotation_subject ,Population ,Fidelity ,Odocoileus ,biology.organism_classification ,Mark and recapture ,White (mutation) ,Age groups ,Biological dispersal ,education ,Ecology, Evolution, Behavior and Systematics ,Electric fence ,Demography ,media_common - Abstract
The number of animal populations enclosed by impermeable fences has increased, which poses issues related to the behavior of individuals and populations. Despite the increased number of fenced enclosures, there is a paucity of survival and fidelity data on white-tailed deer (Odocoileus virginianus) from fenced enclosures. Therefore, we examined marked deer recaptures and resightings over 13 years for an enclosed population of white-tailed deer in Oklahoma, USA, to estimate survival and fidelity parameters. We found that a step model was the best model of survival for both sexes. Survival of females and males was greater after hunting was suspended. Average female survival was 77% before hunting was suspended but increased to 98% after. Male survival was also greater after (99%) hunting was suspended compared to before (58%). Females exhibited greater site fidelity (84–94%) than males for all age groups except old individuals, which showed similar site fidelities for males and females. Fidelity was highest for old males (85%), followed by adult (74%), fawn (61%), and yearling males (56%). Our high-tensile electric fence allowed management goals to be achieved through increased survival while potentially maintaining genetic diversity through the exchange of limited numbers of individuals from surrounding areas. However, if the goal is to confine deer to limit disease spread or protect sensitive areas (e.g., airports) from deer encroachment, then other fence designs may be necessary, because our fence was not completely effective at controlling deer movements for these purposes.
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- 2009
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45. Assessing the Helicopter and Net Gun as a Capture Technique for White-Tailed Deer
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John S. Lewis, David G. Hewitt, Stephen L. Webb, Fred C. Bryant, and Mickey W. Hellickson
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Veterinary medicine ,Ecology ,biology ,Odocoileus ,biology.organism_classification ,Highly selective ,Broken legs ,Antler ,parasitic diseases ,General Earth and Planetary Sciences ,Ecology, Evolution, Behavior and Systematics ,Nature and Landscape Conservation ,General Environmental Science ,Capture myopathy - Abstract
The helicopter and net gun is a technique used to capture white-tailed deer (Odocoileus virginianus) and is useful in a variety of habitat types and at various population densities with the ability to be highly selective. During capture, deer may sustain injuries or even die as a result of capture and handling, and may also be prone to capture myopathy. Therefore, our objectives were to determine 1) type and frequency of injuries sustained during the helicopter and net-gun capture, and 2) the effects of capture on survival of radiocollared deer. We captured 3,350 white-tailed deer from 1998 to 2005 using a net gun fired from a helicopter on 5 southern Texas, USA, ranches. Additionally, we captured 51 yearling males and 49 mature (≥4 yr of age) males and fitted them with radiocollars to monitor their survival. We recorded injuries and mortalities during capture and ranked the seriousness of injuries on a scale from 0 to 4. We recorded 281 injuries (8.4%) and as a result of capture, at least 206 deer had broken antlers (6.1%), 55 were injured (1.6%), and 20 were direct mortalities (0.6%). The most common antler injury was broken antler tines and the most common body injury was broken legs. Postcapture mortality rates were low (1%) for this capture method. Based on capture-related injuries, mortalities, and postcapture survival, we found the helicopter and net gun to be a safe capture technique compared to other capture techniques, particularly when conditions are favorable.
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- 2008
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46. Scale of Management for Mature Male White-Tailed Deer as Influenced by Home Range and Movements
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Mickey W. Hellickson, David G. Hewitt, and Stephen L. Webb
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Ecology ,biology ,Home range ,Odocoileus ,biology.organism_classification ,Scale (music) ,White (mutation) ,Animal science ,Age groups ,General Earth and Planetary Sciences ,Biological dispersal ,Ecology, Evolution, Behavior and Systematics ,Nature and Landscape Conservation ,General Environmental Science - Abstract
The scale at which populations use landscapes influences ecological processes and management. We used dispersal and home-range data of 3 age groups of male white-tailed deer (Odocoileus virginianus) to determine the scale at which management will be effective. Home-range size at 5.5 years of age (182 ha ± 24.9 SE) was 56% smaller (P 10,000 ha were needed to manage >50% of original yearling males found on the property, whereas properties of 4,500 ha would maintain 50% of original middle-aged (2.5–4.5 yr of age) and mature mal...
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- 2007
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47. Survival and Cause-Specific Mortality of Mature Male White-Tailed Deer
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Stephen L. Webb, Mickey W. Hellickson, and David G. Hewitt
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Ecology ,Cause specific mortality ,Biology ,Odocoileus ,biology.organism_classification ,White (mutation) ,Animal science ,Cohort ,General Earth and Planetary Sciences ,Population management ,Ecology, Evolution, Behavior and Systematics ,Nature and Landscape Conservation ,General Environmental Science ,Demography - Abstract
Understanding sources of male deer mortality is a prerequisite to a successful management program, especially in Texas, USA, where white-tailed deer (Odocoileus virginianus) are the most economically important game species. South Texas, USA, is one of the few areas where males reach older age classes (≥4.5 yr), in part because of intense population management. Therefore, we obtained survival rates and causes of mortality of 48 mature male deer in south Texas, USA, over 2 years. We calculated Kaplan–Meier survival estimates during 2 study years modified for a staggered-entry design and annual survival rates for one cohort of deer from 1998 to 2004 using recapture and radiotelemetry data. We documented 21 mortalities (16 harvest and 5 nonhunting mortalities). Average annual survival of the known-aged 1998 cohort was 82% with 52% of surviving to 6.5 years of age. Survival in study year 2 (0.497 ± 0.069) was less than in study year 1 (0.781 ± 0.073; P = 0.0047), largely because males had finally reac...
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- 2007
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48. Incorporating within- and between-patch resource selection in identification of critical habitat for brood-rearing greater sage-grouse
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Matthew R. Dzialak, Jeffrey B. Winstead, Chad V. Olson, Stephen L. Webb, and Seth M. Harju
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Water resources ,Identification (information) ,Resource (biology) ,Ecology ,Critical habitat ,Habitat ,Ecological Modeling ,Environmental science ,Common spatial pattern ,Vegetation ,Cartography ,Selection (genetic algorithm) - Abstract
Introduction Incorporating information on animal behavior in resource-based predictive modeling (e.g., occurrence mapping) can elucidate the relationship between process and spatial pattern and depict habitat in terms of its structure as well as its function. In this paper, we assigned location data on brood-rearing greater sage-grouse (Centrocercus urophasianus) to either within-patch (encamped) or between-patch (traveling) behavioral modes by estimating a movement-based relative displacement index. Objectives were to estimate and validate spatially explicit models of within- versus between-patch resource selection for application in habitat management and compare these models to a non-behaviorally adjusted model. Results A single model, the vegetation and water resources model, was most plausible for both the encamped and traveling modes, including the non-behaviorally adjusted model. When encamped, sage-grouse selected for taller shrubs, avoided bare ground, and were closer to mesic areas. Traveling sage-grouse selected for greater litter cover and herbaceous vegetation. Preference for proximity to mesic areas was common to both encamped and traveling modes and to the non-behaviorally adjusted model. The non-behaviorally adjusted map was similar to the encamped model and validated well. However, we observed different selection patterns during traveling that could have been masked had behavioral state not been accounted for. Conclusions Characterizing habitat that structured between-patch movement broadens our understanding of the habitat needs of brood-rearing sage-grouse, and the combined raster surface offers a reliable habitat management tool that is readily amenable to application by GIS users in efforts to focus sustainable landscape management.
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- 2015
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49. Mapping areas of spatial-temporal overlap from wildlife tracking data
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Jed A, Long, Stephen L, Webb, Trisalyn A, Nelson, and Kenneth L, Gee
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Methodology Article - Abstract
Background The study of inter-individual interactions (often termed spatial-temporal interactions, or dynamic interactions) from remote tracking data has focused primarily on identifying the presence of such interactions. New datasets and methods offer opportunity to answer more nuanced questions, such as where on the landscape interactions occur. In this paper, we provide a new approach for mapping areas of spatial-temporal overlap in wildlife from remote tracking data. The method, termed the joint potential path area (jPPA) builds from the time-geographic movement model, originally proposed for studying human movement patterns. Results The jPPA approach can be used to delineate sub-areas of the home range where inter-individual interaction was possible. Maps of jPPA regions can be integrated with existing geographic data to explore landscape conditions and habitat associated with spatial temporal-interactions in wildlife. We apply the jPPA approach to simulated biased correlated random walks to demonstrate the method under known conditions. The jPPA method is then applied to three dyads, consisting of fine resolution (15 minute sampling interval) GPS tracking data of white-tailed deer (Odocoileus virginianus) collected in Oklahoma, USA. Our results demonstrate the ability of the jPPA to identify and map jPPA sub-areas of the home range. We show how jPPA maps can be used to identify habitat differences (using percent tree canopy cover as a habitat indicator) between areas of spatial-temporal overlap and the overall home range in each of the three deer dyads. Conclusions The value of the jPPA approach within current wildlife habitat analysis workflows is highlighted along with its simple and straightforward implementation and interpretation. Given the current emphasis on remote tracking in wildlife movement and habitat research, new approaches capable of leveraging both the spatial and temporal information content contained within these data are warranted. We make code (in the statistical software R) for implementing the jPPA approach openly available for other researchers. Electronic supplementary material The online version of this article (doi:10.1186/s40462-015-0064-3) contains supplementary material, which is available to authorized users.
- Published
- 2015
50. WATER QUALITY AND SUMMER USE OF SOURCES OF WATER IN TEXAS
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Cody J. Zabransky, Rebbecca S. Lyons, Stephen L. Webb, and David G. Hewitt
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Hydrology ,Irrigation ,biology ,business.industry ,Ecology ,fungi ,Wildlife ,Odocoileus ,Total dissolved solids ,biology.organism_classification ,Arid ,Environmental science ,Livestock ,Water quality ,business ,Ecology, Evolution, Behavior and Systematics ,Water use - Abstract
In southern Texas, the lack of free-standing water that results from low rainfall or poor water quality can be deleterious to wildlife. Water quality can deteriorate rapidly due to evaporation during summer in southern Texas, and high concentrations of salts in water can cause physiological distress; however, little research has addressed water quality and needs of wildlife in arid environments. Our objectives were to: 1) establish water use patterns of wildlife during summer, 2) correlate visitation rates to temperature and rainfall events, and 3) monitor water quality in earthen stock ponds and concrete troughs during summer. We recorded visits to water by 17 species of wildlife and cattle. Cattle, feral pigs (Sus scrofa), and white-tailed deer (Odocoileus virginianus) had peak watering times that differed from one another. Track surveys showed a generally negative correlation between rainfall and wildlife watering frequency. Troughs had significantly higher total dissolved solids and pH than p...
- Published
- 2006
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