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Many global wildlife populations are experiencing unprecedented declines. Estimates of population abundance are needed to effectively manage common species and to conserve vulnerable species. Camera traps have advanced as wildlife monitoring tools for ungulates and can provide improved methods of estimating population abundance. Little is known, however, about how camera traps set for ungulates compare with traditional methods (e.g., ground and aerial surveys) used simultaneously. From 2012 to 2014, we captured and radio collared 34 female and 32 male bighorn sheep (Ovis canadensis) in a closed population in Utah, USA. Each collar had a unique letter and number combination. We then estimated number of young, females and yearlings, males and population abundance using multiple methods simultaneously: helicopter surveys, resight surveys performed from the ground, camera trap surveys using marked but not individually identifiable individuals and camera trap surveys using marked and individually identifiable animals. All methods estimated similar abundance. Across years, ages and sexes, however, camera trap surveys produced the most consistent and precise estimates of abundance for adult females and yearlings, lambs and the population. That method was less intrusive and safer than helicopter surveys. Our results indicate that camera trap surveys using photographs of marked animals in which the majority of the population visits a specific resource can produce precise estimates of abundance that are safer, as well as less intrusive and expensive than traditional methods. Using camera traps also creates a permanent record of photographs that can be archived and reanalyzed to answer future ecological and population questions. Finally, this method of estimating abundance can be used in other areas with ungulates that congregate around resources (e.g., watering sites or mineral licks).

The mule deer (Odocoileus hemionus) is an ungulate species that is distributed in a range from western Canada to central Mexico. Mule deer are an essential source of food for many predators, are relatively abundant, and commonly make broad migration movements. A clearer understanding of the mule deer genome can improve our knowledge of its population genetics, movements, and demographic history, aiding in conservation efforts. Their large population size, continuous distribution, and diversity of habitat make mule deer excellent candidates for population genomics studies; however, few genomic resources are currently available for this species. Here, we sequence and assemble the mule deer genome into a highly contiguous chromosome-length assembly for use in future research using long-read sequencing and Hi-C technologies. We also provide a genome annotation and compare demographic histories of the mule deer and white-tailed deer using the pairwise sequentially Markovian coalescent model. We expect this assembly to be a valuable resource in the continued study and conservation of mule deer.

Free water can influence the ecology of desert species. While the use of free water is influenced by physiological factors (e.g., species‐specific water requirements, moisture in forage, temperature), nonphysiological factors, such as habitat characteristics and interspecific interactions, are also important. In fact, for species of concern, interspecific interactions and habitat can be important factors influencing their spatial and temporal use of the landscape and its resources. The kit fox (Vulpes macrotis) is a small carnivore considered to be a species of concern over much of its range, and two of the most important conservation challenges it faces are related to (1) habitat and (2) predation/competition by intraguild species. Our objective was to determine the influence of habitat characteristics, predators (bobcats [Lynx rufus], coyotes [Canis latrans]), and potential competitors (badgers [Taxidea taxus], gray foxes [Urocyon cinereoargenteus]) on the use of water by kit foxes. From June to September 2010–2012, we used remote cameras to monitor carnivores at 63 water sources in the Mojave Desert. We used zero‐inflated mixed‐effects models and a two‐stage model selection analysis to evaluate the influence of habitat, predators, and competitors on spatial visits to water by kit foxes. We also assessed temporal avoidance of intraguild predators and competitors by kit foxes at water sources using a coefficient of overlap. We found that visual obscurity, overhead canopy cover, badgers, and coyotes influenced spatial visits of kit foxes. In addition, kit foxes exhibited strong temporal overlap with badgers and bobcats, moderate temporal overlap with gray foxes, and weak temporal overlap with coyotes. Taken together, our study demonstrates that the spatial and temporal use of water sources by kit foxes is dynamic, depending on habitat characteristics and the activity of intraguild predators and competitors.

Background Conservation and management of migratory animals has gained attention in recent years, but the majority of research has focused on stereotypical ‘migrant’ and ‘resident’ behaviors, often failing to incorporate any atypical behaviors or characterize migratory behaviors beyond distance and timing of the migration. With migration threatened by anthropogenic development and climate change, it is crucial that we understand the full range of migratory behaviors. Our objective was to demonstrate and characterize the variation in migration strategies, including typical and atypical migratory behaviors for mule deer (Odocoileus hemionus) in Utah, USA. Methods Because calculation of common metrics such as distance, timing, and use of stopovers during migration did not adequately describe the variation we observed in migratory behavior for this species—particularly when animals visited multiple (> 3) ranges for extended lengths of time—we developed additional methods and categories to describe observed variation in migratory behavior. We first categorized trajectories based on the number of discrete, separate ranges and range shifts between them. Then, we further characterized the variation in migration strategies by examining the timing, duration, and distance traveled within each of the categories. We also examined if and how frequently individual deer switched among categories from year to year. Results We classified 1218 movement trajectories from 722 adult female mule deer, and found that 54.4% were dual-range migrants, who made one round-trip to one distinct range. Multi-range migrants (23.6%) made one round-trip during which they stayed at multiple discrete ranges. Commuters (1.0%) traveled to the same range multiple times, and poly migrants (1.5%) made multiple round-trips to different ranges. Gradual movers (2.5%) did not show a discrete range shift but moved gradually between ranges, whereas residents (12.6%) never left their home ranges, and dispersers (4.4%) left but never returned. Of the deer that we monitored for multiple years, 51.2% switched among categories. Conclusion We conclude that the substantial number of atypical migratory strategies, as well as the number of deer that switched categories, underlines the importance of studying these less-stereotyped behaviors that may be exhibited by large proportions of populations. Acknowledging and investigating the full complexity and diversity in migratory strategies might uncover unknowns with respect to underlying factors and drivers of migration, and can help shape effective conservation strategies.

Pressure from hunting can alter the behavior and habitat selection of game species. During hunting periods, cervids such as elk (Cervus canadensis) typically select for areas further from roads and closer to tree cover, while altering the timing of their daily activities to avoid hunters. Our objective was to determine the habitat characteristics most influential in predicting harvest risk of elk. We captured 373 female elk between January 2015 and March 2017 in the Uinta-Wasatch-Cache National Forest and surrounding area of central Utah, USA. We determined habitat selection during the hunting season using a resource selection function (RSF) for 255 adult cow elk. Additionally, we used a generalized linear mixed model to evaluate risk of harvest based on habitat use within home ranges (3rd order selection) as well as the location of the home range on the landscape to evaluate vulnerability on a broader scale. Female elk selected for areas that reduced hunter access (rugged terrain, within tree cover, on private land). Age, elevation and distance to roads within a home range were most influential in predicting harvest risk (top model accounted for 36.2% of AIC weight). Elevation and distance to trees were most influential in predicting risk when evaluating the location of the home range (top model accounted for 42.1% of AIC weight). Vulnerability to harvest was associated with proximity to roads. Additionally, survival in our landscape decreased with age of femaleelk.

Human recreation can negatively affect wildlife, particularly on weekends when human activity is highest (i.e., the weekend effect). Much of what we understand about the weekend effect is based on research conducted on diurnal species, which have greater temporal overlap with humans. Because nocturnal species generally avoid times when humans are active, they are likely less affected by anthropogenic activity on weekends. Our objective was to test the weekend effect in relation to the degree of nocturnality of mammals in a recreational area. We predicted that as nocturnality increased, the effect of human activity would decrease. To address our objective, we placed 50 remote cameras along the Diamond Fork River in Utah from January to June 2015. We found that three out of the four focal species supported our predictions. Mule deer (crepuscular) reduced activity throughout our entire study area during weekends and avoided campgrounds. Beavers and mountain lions (both nocturnal) did not negatively respond to increased human activity. Raccoons (nocturnal) reduced activity during weekends, but only within campground areas. Our findings indicate that as the temporal overlap increases between wildlife and humans, so does the influence that humans have on wildlife.

Estimating abundance or distribution of species that are scarce or difficult to detect is challenging for wildlife biologists. Pygmy rabbits (Brachylagus idahoensis) are secretive, sagebrush (Artemisia spp.) obligates of conservation concern that occupy the Intermountain West, USA. These unique leporids are difficult to monitor; however using remote cameras in conjunction with ranking of burrow activity may help refine sampling techniques for these mammals. We classified and deployed remote cameras at 405 burrows of pygmy rabbits between 2006 and 2010 in six study areas across Utah, USA. We ranked burrows based on the appearance of fecal pellets, as well as the condition of burrow entrances. We also documented the presence of pygmy rabbits and potential competitors and predators of pygmy rabbits at burrows using remote cameras. We used mixed-effects, zero-inflated negative binomial models and AIC model selection to evaluate the relative influences of burrow activity ranking, season, and rate of photographs for potential competitors and predators of pygmy rabbits on photo rates of pygmy rabbits. The top 2 models supported a simplified (active or inactive) burrow classification system and accounted for 45% of AIC weight. Rates of pygmy rabbit photographs were further influenced by meters from habitat edge (β = 0.0008 ± 0.0004, 95% CI = 7.07E-05–0.002), photo rate of cottontail rabbits (β = 0.31 ± 0.11, 95% CI = 0.08–0.53), and were higher during summer than other times of the year (β = 0.38 ± 0.19, 95% CI = 0.01–0.74). Mean number of days to detection of pygmy rabbits at burrow complexes classified as active was four (SE = 0.61), and a two-week sampling period was needed to capture 81% of first detections. Our results refine commonly used ranking criteria of burrow complexes to a 2-level scale (active and inactive), and also emphasize the use of remote cameras as an effective technique for quantifying activity of pygmy rabbits at burrow complexes. Such information can help researchers and land managers more effectively survey this species for conservation and management efforts.

Biological invasions are responsive to changing wildfire regimes related to human activities that are altering biological communities. Our objective was to investigate how fire, rodent activity, and competition among plant species modify plant community structure, invasion patterns, and vulnerability to altered fire regimes. We imposed experimental fires, and reduced rodent density using fencing in a full factorial design and quantified competitive interactions among plant species in the northeast Mojave Desert that has experienced dramatic increases in plant invasion and fire in recent years. Vegetation surveys were conducted in the experimental plots to determine plant density, cover, and biomass of herbaceous plants over a 5-year period. Rodent exclusion increased the density, cover, and biomass of Bromus rubens, an invasive annual grass, and density of forb species. In contrast, rodent exclusion decreased the density, cover, and biomass of Schismus spp. another dominant annual invader. Fire increased Schismus spp. and forb species density, cover, and biomass but decreased B. rubens density. Negative spatial correlation between B. rubens and Schismus spp., and forbs indicated interspecific competition among the dominant plant species. Fire reduced rodent community diversity (Shannon’s) 2.5-fold, which was correlated with increases in B. rubens cover and biomass, and native forb diversity. Fire, high rodent diversity, and competition from the other plant species may decrease fire potential in our study system by reducing the density and biomass of B. rubens, which because of its taller growth form tends to ignite and carry fire better than Schismus spp. and forbs.

Abstract ContextWildlife biologists accumulate large quantities of images from remote cameras, which can be time- and cost-prohibitive to archive and analyse. Remote-camera projects would benefit from not setting cameras longer than needed and not analysing more images than needed; however, there is a lack of information about optimal deployment time required for remote-camera surveys to estimate ungulate abundance. AimsThe objective was to estimate abundance of adult females in a population of Rocky Mountain bighorn sheep (Ovis canadensis canadensis) in Utah, USA, from 2012 to 2014, and determine whether this type of study can be conducted more efficiently. Because females are the most important cohort for population growth, remote cameras were set at three water sources and mark–resight models in Program MARK were used. MethodsWe compared estimated abundance of collared and uncollared females by number of days cameras were set using 31 replicated abundance estimates from each year starting 1 July. Each replicated estimate used a different number of days and photographs from a 62-day sampling period (1 July to 31 August). Key resultsAbundance estimates ranged from 44 to 98 animals. Precise estimates of abundance, however, were obtained with only 12 days of sampling in each year. By analysing only 12 days of images rather than 62 days in all years, the estimated mean of 58 adult females would have changed by only 7 individuals (±4 individuals, range=3–10 animals), the s.e. would have increased by a mean of only 4 individuals (±1.6, range=2.0–5.2 individuals) and a mean of only 18% (±10.5%, range=8–29%) of images would have been analysed. Across the study, analysis of >23000 (>80%) images could have been avoided, saving time and money. ConclusionsThe results indicate that an asymptotic relationship exists between estimated abundance of female bighorn sheep and remote-camera deployment time. ImplicationsThe mark–resight methods used in the present study would work for other ungulates in which individuals are radio collared or marked using remote cameras set at water sources, trail crossings or mineral licks. These findings can help researchers reduce cost of setting, servicing, archiving and analysing photographs from remote cameras for ungulate population monitoring.

Climate change is predicted to decrease the availability of water in deserts, potentially increasing competition for water. We wanted to determine if competition between top carnivores in deserts of western North America (i.e., coyote (Canis latrans) and bobcat (Lynx rufus)) was influenced by water availability. Evidence suggests that coyotes and bobcats do not compete for water in the Chihuahuan Desert, but this desert receives 2–3X more precipitation when water is limiting than other western deserts. If water availability influences competition, we predicted that bobcats (subordinate to coyotes) would avoid water sources used by coyotes in deserts where water availability is low when demand is high. We monitored 105 water sources for three years in the Great Basin and Mojave Deserts and captured 810 bobcat visits and 2247 coyote visits. We found no evidence that bobcats avoided water sources used by coyotes. In contrast, bobcat visitation to water increased as coyote visitation increased. It does not appear that bobcats and coyotes compete for water, spatially or temporally (on an hourly scale), in the Great Basin and Mojave Deserts. Our study suggests that anthropogenic water sources may alleviate the effects of environmental water loss on the interactions between top mammalian carnivores.

The combined effects of global climate change and increased anthropogenic use of free water are likely to cause decreases in availability and surface area of water in arid environments. Climate change and water loss are predicted to alter community dynamics, but identifying mechanisms underlying differential responses of species remains a critical conservation challenge. Bats drink in flight and rely on accessible water sources, yet the ability to access water is a function of flight maneuverability. By reducing the size of water sources (to simulate predicted water loss due to climate change/increased human use), we demonstrated species-specific responses by desert bats based on differences in morphology and flight maneuverability. Under natural conditions, less-maneuverable bats selected larger water sources while maneuverable bats exhibited no preference. When we experimentally reduced surface area, larger, less-maneuverable bats experienced a 69% decrease in the proportion of drinking attempts that were successful ( p

Monitoring animal populations can be challenging, particularly when working with species that are cryptic, rare, or occur at low densities. The northern river otter (Lontra canadensis) is a cryptic, semi-aquatic carnivore that has been intensively studied in recent decades, yet much of what is known about its ecology is a result of studies that have employed indirect methods of detection and monitoring. These indirect methods, such as latrine or other sign surveys, have been the primary approach used for studying distribution, abundance, and habitat use of otters, with minimal representation of direct methods. In this study, we compared direct (camera traps) and indirect (scat count surveys) methods of evaluating detection probabilities and site use patterns of otters at latrines. We found that the direct method produced a significantly greater monthly detection probability than the indirect method and that camera surveys resulted in fewer occurrences of false negatives than scat surveys. However, the number of scats deposited at a site was positively correlated with number of visits by otters at a site (Tau-b = 0.675). Thus, while cameras outperformed scat counts in terms of detection, the two methods were comparable in determining intensity of site use. We conclude that, depending on the parameter of interest, scat counts may be an acceptable surrogate for more direct methods of monitoring otters and other cryptic species. We caution, however, that in the absence of comparative methodological data, direct methods such as camera trapping should be preferred when making inferences about animal distribution, abundance, or habitat use.

Biotic resistance and disturbance are fundamental processes influencing plant invasion outcomes; however, the role of consumers in regulating the establishment and spread of plant invaders and how disturbance modifies biotic resistance by consumers is unclear. We document that fire in combination with experimental exclusion of rodent consumers shifted a native desert shrubland to a low-diversity, invasive annual grassland dominated by Bromus tectorum (cheatgrass). In contrast, burned plots with rodents present suppressed invasion by cheatgrass and developed into a more diverse forb community. Rodents created strong biotic resistance to the establishment of aggressive plant invaders likely through seed and seedling predation, which had cascading effects on plant competition and plant community diversity. Fire mediated its positive effects on plant invaders through native plant removal and by decreasing the abundance and diversity of the rodent community. The experimental disruption of plant and consumer-mediated biotic resistance of plant invaders using fire and rodent exclusion treatments provides strong evidence that native plants and rodents are important regulators of plant invasion dynamics and plant biodiversity in our study system. While rodents conferred strong resistance to invasion in our study system, fluctuations in rodent populations due to disturbance and climatic events may provide windows of opportunity for exotic plant species to escape biotic resistance by rodent consumers and initiate invasions.

Introduced species can impact native communities by altering competition dynamics. Large exotic species, such as the horse ( Equus caballus ), may have a competitive advantage over smaller native species and could exclude them from access to limited resources. Our objective was to determine the influence of the exotic horse on the use of water by native species in a semi-arid environment where availability of water is limited. From July 2010 to August 2011, we used remote cameras to monitor water sources in the Great Basin Desert where horses had drinking access and where horses were excluded (with fencing) to compare 1) composition of native communities and 2) water usage by native species. We captured 96,601 images representing 40 species of birds (29,396 images) and 13 species of mammals (67,205 images). Of the 67,205 images of mammals, 79% contained horses. Horses were associated with decreased richness and diversity of native species at water sources. Furthermore, native species had fewer visits and spent less time at water sources frequented by horses. Our results indicated that horses displaced other species at water sources providing evidence of a negative influence on how communities of native wildlife access a limited resource in an arid environment.

Predator control is often implemented with the intent of disrupting top-down regulation in sensitive prey populations. However, ambiguity surrounding the efficacy of predator management, as well as the strength of top-down effects of predators in general, is often exacerbated by the spatially implicit analytical approaches used in assessing data with explicit spatial structure. Here, we highlight the importance of considering spatial context in the case of a predator control study in south-central Utah. We assessed the spatial match between aerial removal risk in coyotes (Canis latrans) and mule deer (Odocoileus hemionus) resource selection during parturition using a spatially explicit, multi-level Bayesian model. With our model, we were able to evaluate spatial congruence between management action (i.e., coyote removal) and objective (i.e., parturient deer site selection) at two distinct scales: the level of the management unit and the individual coyote removal. In the case of the former, our results indicated substantial spatial heterogeneity in expected congruence between removal risk and parturient deer site selection across large areas, and is a reflection of logistical constraints acting on the management strategy and differences in space use between the two species. At the level of the individual removal, we demonstrated that the potential management benefits of a removed coyote were highly variable across all individuals removed and in many cases, spatially distinct from parturient deer resource selection. Our methods and results provide a means of evaluating where we might anticipate an impact of predator control, while emphasizing the need to weight individual removals based on spatial proximity to management objectives in any assessment of large-scale predator control. Although we highlight the importance of spatial context in assessments of predator control strategy, we believe our methods are readily generalizable in any management or large-scale experimental framework where spatial context is likely an important driver of outcomes.

The horse (Equus caballus) is a feral ungulate that currently exceeds target population sizes in many areas of western North America. Horses are behaviorally dominant over native ungulates and outcompete the latter for access to water sources. However, a better understanding of the broader spatial and temporal implications of horse‐induced competition on access to water by native ungulates will enable better conservation and management of native species. Our objective was to determine whether pronghorn (Antilocapra americana) and mule deer (Odocoileus hemionus) spatially or temporally altered their use of water to minimize interactions with horses. From 2010 to 2014, we used remote cameras to monitor ungulates at 32 water sources in the Great Basin Desert. We evaluated spatial and temporal partitioning by these species at water sources using generalized linear models, mixed‐effects models, and Mann–Whitney U tests. We found that both native ungulates used water sources less often where horse activity at water sources was high, indicating that spatial avoidance occurred. Further, we observed significant differences in peak arrival time for pronghorn, but not mule deer at horse‐occupied sites versus sites where horses were absent or uncommon, indicating that temporal avoidance may be more important for pronghorn than mule deer. Because mule deer are primarily crepuscular and nocturnal whereas horses are largely diurnal, we did not expect to observe a temporal shift for mule deer. We also found strong support for the interactive negative effect of elevated temperature and subsequent increased activity of horses at water sources on drinking patterns of pronghorn and mule deer. Our findings indicate that feral horses further constrain access to an already limited resource for native species in a semi‐arid environment.

Diet of the northern river otter (Lontra canadensis (Schreber, 1777)) has been examined throughout much of its range and across many habitat types. Few studies have examined prey selection based on prey abundance estimates, however, and prey selection results have been inconsistent. We determined composition, seasonal variation, and prey selection of otter diet in northern Utah comprising multiple habitat types and prey communities. We evaluated the hypothesis that otters take prey according to availability and in inverse proportion to swimming ability. Fish was the primary class of prey taken by otters (96.5%), followed by crustaceans (16.9%). Among families, otter diet was composed primarily of Salmonidae and Cottidae, the two families that dominated the fish community of the main-channel habitat. Otter diet varied seasonally for nearly all classes (G[24] = 127.8, P < 0.001) and families (G[18] = 132.94, P < 0.001) of prey. In particular, fish occurrence was lower during summer than during other seasons (P ≤ 0.05), whereas crustacean (i.e., crayfish (Astacoidea)) occurrence was higher (G[3] = 71.1, P < 0.001). At the family level, occurrence of Salmonidae was greatest during fall (G[3] = 11.7, P < 0.01). Within one of our habitat types, we found otters to select for prey in proportion to abundance and in inverse proportion to swimming ability, with otters selecting for Catostomidae and Cyprinidae, against Salmonidae, and Cottidae according to its abundance. We conclude that habitat type may be the initial driver of prey selection, while factors such as abundance, agility, and life history of prey may be secondary drivers.

Evaluating how management practices influence the population dynamics of ungulates may enhance future management of these species. For example, in mule deer (Odocoileus hemionus), changes in male/female ratio due to male-biased harvest may alter rates of pregnancy, timing of parturition, and synchrony of parturition if inadequate numbers of males are present to fertilize females during their first estrous cycle. If rates of pregnancy or parturition are influenced by decreased male/female ratios, recruitment maybereduced (e.g., fewerbirths,laterparturition resultinginlower survivaloffawns, andalesssynchronous parturition that potentially increases susceptibility of neonates to predation). Our objectives were to compare rates of pregnancy, synchrony of parturition, and timing of parturition between exploited mule deer populations with a relatively high (Piceance, CO, USA; 26 males/100 females) and a relatively low (Monroe, UT, USA; 14 males/100 females) male/female ratio. We determined rates of pregnancy via ultrasonography and timing of parturition via vaginal implant transmitters. We found no differences in rates of pregnancy (98.6% and 96.6%; z ¼� 0.821; P ¼0.794), timing of parturition (estimate ¼1.258; SE ¼1.672; t ¼0.752; P ¼0.454), or synchrony of parturition (F ¼1.073 P ¼0.859) between Monroe Mountain and Piceance Basin, respectively. The relatively low male/female ratio on Monroe Mountain was not associated with a protracted period of parturition. This finding suggests that relatively low male/female ratios typical of heavily harvested populations do not influence population dynamics because recruitment remains unaffected. 2014 The Wildlife Society.

Abstract ContextTranslocation of wildlife has become common practice for wildlife managers charged with management of animals on increasingly modified landscapes. Mule deer (Odocoileus hemionus) is a species of great interest to the public in western North America, and individuals of this species have been translocated several times, but little has been done to document the outcomes of those translocations. AimOur objective was to evaluate the movement, space use and site fidelity of translocated female mule deer in comparison with resident female deer in Utah, USA. MethodsIn January and March 2013, 102 translocated and 50 resident female mule deer were captured and fitted with radio-transmitters. Movement distances, home range sizes and seasonal range sizes were compared, as well as site fidelity between translocated and resident deer. Key resultsMean distance moved and mean annual home range size were significantly larger for translocated than resident deer in 2013, but not in 2014. Translocated deer demonstrated high site fidelity to their release areas. In total, 75% of surviving deer returned during the fall (September–November) migration to winter range within 7km of release sites. ConclusionsOur results indicate that home range sizes and movements of translocated deer are larger than those of resident deer during the first year after release, but during the second year after release, home range sizes and movements of translocated deer are similar to those of resident deer. ImplicationsThe similar home range sizes and movements of translocated and resident deer >1 year after release, as well as the high site fidelity we observed, suggests that translocation is a strategy managers could use to establish or augment populations of mule deer on winter range.

Reintroductions and translocations of northern river otters have been a common management practice throughout the United States from the 1970s to the 2000s. Though many reintroductions have been successful, popula- tions are not always monitored or evaluated post-release. From 2009 through 2012, we translocated 27 radio-marked otters into the Provo River watershed in northern Utah. Our objective was to determine what factors influenced the translocation-related mortality of otters. We developed a series of a priori models and used logistic regression to deter- mine the most influential factors. We used Akaike's information criterion to evaluate relative model support. We found that the univariate model including body mass bore the most model weight and that body mass was the most important factor influencing the initial survival of translocated otters. Model-averaged β estimates indicated that otters at the high end of body mass were 4 times more likely to survive the translocation than otters at the low end of body mass. Sex was the next most important factor influencing survival, as odds ratios indicated that males were more likely to survive the translocation than females. We urge ecologists and managers to delay the trapping and translocating of otters until young-of-the-year are likely large enough to have a high probability of survival. We further recommend female-biased translocations, as females were less likely to survive translocations. RESUMEN.—La reintroduccion y traslocacion de las nutrias de rio del norte fueron comunes en todo Estados Unidos desde los anos setenta hasta la decada del 2000. Si bien muchas practicas de reintroduccion fueron exitosas, no siempre se monitorea y/o evalua a las poblaciones despues de liberarlas. Entre el ano 2009 y el ano 2012, realizamos la tras - locacion de 27 nutrias de un determinado radio a la linea divisoria del Rio Provo al norte de Utah. Nuestro objetivo fue determinar que factores influyeronn en la mortalidad de las nutrias a causa del traslado. Desarrollamos una serie de modelos a priori y utilizamos la regresion logistica para determinar que factores tuvieron mas influencia. Utilizamos el criterio de informacion de Akaike para evaluar el apoyo relativo del modelo y descubrimos que el modelo univari - able que incluia la masa corporal registraba el peso maximo del modelo, y que la masa corporal fue el factor mas impor- tante que influyo en la supervivencia inicial de las nutrias a las que se habia sometido a la traslocacion. Las estimaciones β promedio del modelo indicaron que las nutrias que se encontraban en el extremo mas alto de los indicadores de masa corporal tenian cuatro veces mas probabilidades de sobrevivir al traslado que las nutrias que se encontraban en el extremo mas bajo. El sexo fue el siguiente factor mas importante que influyo en la supervivencia, los indices de proba- bilidad indicaron que los machos tenian mas probabilidades de sobrevivir el traslado que las hembras. Solicitamos a los ecologistas y a los encargados de cuidar el medioambiente que posterguen la colocacion de trampas y el traslado de nutrias hasta que los juveniles sean lo suficientemente grandes como para tener una mayor probabilidad de super- vivencia. Ademas, recomendamos no trasladar hembras, las cuales mostraron menos probabilidades de sobrevivir a las traslocaciones.

The validity of treating counts as indices to abundance is based on the assumption that the expected detection probability, E(p), is constant over time or comparison groups or, more realistically, that variation in p is small relative to variation in population size that investigators seek to detect. Unfortunately, reliable estimates of E(p) and var(p) are lacking for most index methods. As a case study, we applied the time-of-detection method to temporally replicated (within season) aural counts of crowing male Ring-necked Pheasants (Phasianus colchicus) at 18 sites in southern Minnesota in 2007 to evaluate the detectability assumptions. More specifically, we used the time-of-detection method to estimate E(p) and var(p), and then used these estimates in a Monte Carlo simulation to evaluate bias-variance tradeoffs associated with adjusting count indices for imperfect detection. The estimated mean detection probability in our case study was 0.533 (SE = 0.030) and estimated spatial variation in E(p) was 0.081 (95% CI: 0.057–0.126). On average, both adjusted (for) and unadjusted counts of crowing males qualitatively described the simulated relationship between pheasant abundance and grassland abundance, but the bias-variance tradeoff was smaller for adjusted counts (MSE = 0.003 vs. 0.045, respectively). Our case study supports the general recommendation to use, whenever feasible, formal population-estimation procedures (e.g., mark-recapture, distance sampling, double sampling) to account for imperfect detection. However, we caution that interpreting estimates of absolute abundance can be complicated, even if formal estimation methods are used. For example, the time-of-detection method was useful for evaluating detectability assumptions in our case study and the method could be used to adjust aural count indices for imperfect detection. Conversely, using the time-of-detection method to estimate absolute abundances in our case study was problematic because the biological populations and sampling coverage could not be clearly delineated. These estimation and inference challenges may also be important in other avian surveys that involve mobile species (whose home ranges may overlap several sampling sites), temporally replicated counts, and inexact sampling coverage. RESUMEN La validez de tratar los conteos como indices de abundancia se basa en la suposicion de que la probabilidad de deteccion esperado, E(p), es constante a traves del tiempo o entre grupos de comparacion, o mas realisticamente, que la variacion en p es pequeno en relacion a la variacion en el tamano de la poblacion que los investigadores buscan detectar. Desafortunadamente, las estimaciones confiables de E(p) y var(p) son insuficientes para la mayoria de los metodos de indice. Aplicamos el metodo de tiempo de deteccion a conteos auditivos temporalmente replicados (dentro de la temporada) de machos de Phasianus colchicus en 18 sitios en el sur de Minnesota en 2007, para evaluar los supuestos de detectabilidad. Especificamente, utilizamos el metodo de tiempo de deteccion para estimar E(p) y var(p), y luego usamos estas estimaciones en una simulacion de Monte Carlo para evaluar las compensaciones entre sesgo y variacion asociados con el ajuste de los indices de los conteos para la deteccion imperfecta. La probabilidad de deteccion media estimada en nuestro estudio fue 0,533 (EE = 0,030) y la variacion estimada espacial en E(p) fue de 0,081 (IC 95%: 0,057–0,126). En promedio, los conteos ajustados (para) y los conteos no ajustados de los machos cualitativamente describieron la relacion simulada entre la abundancia de P. colchicus y la abundancia de pastizales, pero la compensacion entre sesgo y variacion fue menor para los conteos ajustados (MSE = 0,003 vs. 0,045, respectivamente). Nuestro estudio apoya la recomendacion general de utilizar, siempre que sea factible, los procedimientos formales para la estimacion de la poblacion (por ejemplo, el marcaje-recaptura, el muestreo por distancia, el muestreo doble) para tomar en cuenta la deteccion imperfecta. Sin embargo, advertimos que la interpretacion de las estimaciones de la abundancia absoluta puede ser complicado, aun si los metodos formales de estimacion son utilizados. Por ejemplo, el metodo de tiempo de deteccion era util para evaluar las suposiciones de detectabilidad en nuestro estudio, y el metodo podria ser utilizado para ajustar los indices de conteo auditivos para la deteccion imperfecta. A la inversa, el uso del metodo de tiempo de deteccion para estimar la abundancia absoluta en nuestro estudio fue problematico porque las poblaciones biologicas y la cobertura de muestreo no podian ser claramente delineados. Estos desafios de estimacion e inferencia tambien pueden ser importantes en otros estudios de aves cuando se tratan de especies moviles (cuyos rangos pueden superponerse sobre varios lugares de muestreo), en conteos temporalmente replicados, y cuando la cobertura de muestreo es inexacta.

Ecosystems are transformed by changes in disturbance regimes including wildfire and herbivory. Rodent consumers can have strong top-down effects on plant community assembly through seed predation, but their impacts on post-germination seedling establishment via seedling herbivory need better characterization, particularly in deserts. To test the legacy effects of fire history, and native rodent consumers on seedling establishment, we evaluated factorial combinations of experimental exclusion of rodents and fire history (burned vs. unburned) on seedling survival of 14 native plant species that vary in their life history strategies and growth form in the Mojave Desert. Seedlings were placed into the experimental plots, and seedling survival was monitored daily for 8 days. The legacy effects of fire history had minimal effects on seedling survival, but rodent exclusion, year, and their interaction were strongly significant. Seedling survival rates were nearly sixfold greater in rodent exclusion plots compared to control plots in 2012 (53 vs. 9%) and 17-fold greater in 2013 (17 vs. 1%). The dramatic increase in seedling mortality from 2012 to 2013 was likely driven by an increase in rodent abundance and an outbreak of grasshoppers that appears to have intensified the rodent effect. There was strong variability in plant species survival in response to rodent herbivory with annual plants and forb species showing lower survival than perennial plants and shrub species. These results indicate that rodent consumers can strongly regulate seedling survival of native plant species with potentially strong regulatory effects on plant community development.

Native fishes worldwide have declined as a consequence of habitat loss and degradation and introduction of non-native species. In response to these declines, river restoration projects have been initiated to enhance habitat and remove introduced fishes; however, non-native fish removal is not always logistically feasible or socially acceptable. Consequently, managers often seek to enhance degraded habitat in such a way that native fishes can coexist with introduced species. We quantified dynamics of fish communities to three newly constructed side channels in the Provo River, Utah, USA, to determine if and how they promoted coexistence between native fishes (nine species) and non-native brown trout (Salmo trutta L.). Native and introduced fishes responded differently in each side channel as a function of the unique characteristics and histories of side channels. Beaver activity in two of the three side channels caused habitat differentiation or channel isolation that facilitated the establishment of native species. The third side channel had greater connectivity to and similar habitat as the main channel of the Provo River, resulting in a similar fish community to main channel habitats (i.e. dominated by brown trout with only a few native fish species). These results demonstrate the importance of understanding habitat preferences for each species in a community to guide habitat enhancement projects and the need to create refuge habitats for native fishes.

Changes in plant community structure and composition of the Mojave Desert in response to greater fire intensity and extent are likely to have strong bottom-up effects on the biological community. The objective of this study was to determine how expansive fire in Mojave Desert impacts small mammal communities across seasons. We sampled small mammals in paired burned (4e5 years post-fire) and unburned areas of Beaver Dam Wash in southwestern Utah. Fire reduced total abundance of small mammals, and species richness and species diversity of the small mammal community. Merriam’s kangaroo rat (Dipodomys merriami) responded positively to fire (15% greater in burned areas). Longtailed pocket mouse (Chaetodipus formosus) and canyon mouse (Peromyscus crinitus) were 91% and 98% less abundant in burned versus unburned areas. The positive response of Merriam’s kangaroo rat to fire is most likely correlated with their preference for open foraging microhabitat while other species captured prefer greater and more diverse cover. Because the small mammal community has been dramatically affected by fire, it is likely that top-down control of vegetation structure will be dominated by Merriam’s kangaroo rat in burned areas, which may promote more open habitat by limiting the growth of annual and perennial grasses.

Bison (Bos bison) were a keystone species in the tallgrass prairie region of the Great Plains of North America. Cattle (Bos taurus) have been described as a functional equivalent to bison and have replaced bison in most of the grassland that remains intact. However, non-grazing behaviors influence grassland dynamics and are dissimilar between bison and cattle. Wallowing behavior (a non-grazing behavior by bison, but not cattle) creates disturbances (wallows) that were a common feature (may have numbered more than 100 million) of tallgrass prairie prior to extirpation of bison and conversion of most land to row-crop agriculture. We hypothesized that wallows are a unique disturbance that significantly influence both the structure and function of tallgrass prairie. We examined the response of plants to wallowing disturbances on Konza Prairie Biological Station, Kansas, where a herd of approximately 200 bison had year-round access to 1000 ha of native tallgrass prairie. We determined the influence of...

An understanding of activity patterns of wildlife in relation to abiotic and biotic factors enables biologists to better understand the ecology of species, manage resources, standardize survey methods, and serve as an index of the relative density of a species. River otters (Lontra canadensis) were radiotracked between June 2002 and October 2003. Using radiotracking data, we conducted exploratory analyses to determine relative influence of abiotic and biotic factors on 2 measures of activity of otters. Abiotic factors included air temperature, barometric pressure, lunar phase, biological season, and time of day; the biotic factor was sex. Activity was measured indirectly via movement rates and directly as the proportion of location attempts recorded as active (PLA). Movement rate was defined as the distance traveled by an otter between consecutive location estimates. Generalized linear mixed models were used to explore the influence of covariates on both measures of otter activity. The model best...

The river otter (Lontra canadensis) has a complex social system, which varies widely across its range. We examined patterns of space use and social interactions for a native population of river otters in southeastern Minnesota. We radiomarked 28 river otters and monitored annual home ranges and core areas, static and dynamic interactions, and site fidelity. We compared these characteristics and interactions between sexes and age classes. Annual home ranges of male river otters were 3.2 times greater than those of females (P = 0.042), and annual core areas of males were 2.9 times greater than those of females (P = 0.083). The static interactions among river otters were extensive, with 69% of the individuals exhibiting core-area overlap. Overall dynamic interactions were positive (i.e., animals were closer together than expected). Males used 74% of their year 1 home range during year 2, and females used 75%. Females on average used only 39% of their core area from year 1 during year 2, whereas males used 65%. In general, conspecifics were not excluded from home ranges or core areas and signs of cooperation were evident, suggesting that river otters in southeastern Minnesota were social rather than territorial.

Knowledge of the habitat and spatial characteristics of natal dens used by female river otters (Lontra canadensis) is limited to a few observations. Documentation of these characteristics in human-altered landscapes may improve management opportunities for this species. We monitored 8 adult (>2 y old) radio-marked female otters during the natal denning season (March–May) in southeastern Minnesota during 2003–2004 and quantified 10 micro- and 2 macro-habitat characteristics of dens. Females began denning in March, with a mean initiation date of 31 March, and used natal dens for a mean of 49 d (se = 3). Two females used man-made brush piles as dens, four used small limestone caves, one used a cavity in the roots of a big-toothed aspen (Populus grandidentata) and one used a beaver (Castor canadensis) bank-den. Dens were located a mean of 316 m (se = 79) from the nearest body of water and averaged 61 m (se = 15) of elevation higher than the nearest body of water. Seven of eight females placed dens ou...

The Heron Lake System historically has been an important resource for waterfowl in Southern Minnesota, USA. In the early 1900s, the system was a major nesting, feeding, and staging area for breeding and migrating waterfowl mainly due to the extensive growth of sago pondweed, Stuckenia pectinata. In recent years, the abundance of S. pectinata has decreased dramatically. We conducted a study from 2002 through 2003 to identify factors limiting the success of S. pectinata. Distribution and biomass of S. pectinata differed significantly over the years of this study. Biomass was related to environmental factors, including water transparency and water temperature early in the season. Water transparency during May (time of early growth) had a negative relationship with maximum biomass at each site over all years. Water temperature had a positive relationship with increases in seasonal biomass yield of S. pectinata in the Heron Lake System.

We studied patterns of and factors influencing abundance of hispid cotton rats (Sigmodon hispidus) in tallgrass prairie habitats from autumn 1981 to spring 2001 at the Konza Prairie Biological Station, Kansas. Abundance of cotton rats was low during autumn (X ¼ 0.57 individuals/trapline) and extremely low in spring (X ¼ 0.04 individuals/trapline). Autumn abundance varied widely in 20 years (range: 0.00‐2.50 individuals/trapline) and among 14 sites (0.05‐1.35 individuals/trapline). Spring prairie fires had a positive influence on cotton rats during the 1st (X ¼ 0.8 individuals/trapline) and 2nd autumns (X ¼ 1.0 individuals/trapline), but not during the 3rd or later autumns (X ¼ 0.2 individuals/trapline). Cotton rats were associated strongly with lowland prairie relative to breaks and upland prairie. Autumn abundance was correlated positively with previous winter (December‐ February) average maximum temperature, but was not correlated with previous winter precipitation, summer (June‐August) average maximum temperature, summer precipitation, or aboveground net primary productivity. Although previous winter maximum temperature accounted for only 32% of interautumn variation in abundance, winter harshness appears to be the major factor driving temporal variation in autumn abundance of hispid cotton rats.

Elliot's short-tailed shrews (Blarina hylophaga) were studied in tallgrass prairie at Konza Prairie Biological Station, Kansas. Based on sampling of 14 permanent traplines from autumn 1981 to spring 1999, relative abundance was high in autumn (X = 2.5 ± 0.4 SE shrews/trapline) but very low in spring (

As invasive grasses and fire increase in frequency and extent in North American deserts, they have the potential to affect animal communities through bottom-up forces. We experimentally tested the effects of fire on rodent communities of the Great Basin and Mojave Deserts. Fire decreased the abundance, richness, and diversity of rodents in the Great Basin after fire. In the Mojave, abundance was unaffected and diversity and species richness were greater on burned than unburned plots 4 months after fire. The effects of fire on rodent communities tended to decrease over time. The differences in effects between the deserts may be due to differences in the foraging preferences of the dominant species at each site. As these species are primarily herbivorous, short-term changes to the rodent community could have long-term implications by affecting the recovery of the plant community after fire.