Search

Copyright of Conservation Biology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Upper respiratory tract disease (URTD) in North American tortoises (Gopherus) has been the focus of numerous laboratory and field investigations, yet the prevalence and importance of this disease remains unclear across many tortoise populations. Furthermore, much research has been focused on understanding diagnostic biomarkers of two known agents of URTD, Mycoplasma agassizii and Mycoplasma testudineum, yet the reliability and importance of these diagnostic biomarkers across populations is unclear. Gopher Tortoises (Gopherus polyphemus) have experienced significant declines and are currently protected range wide. Geographically, Alabama represents an important connection for Gopher Tortoise populations between the core and periphery of this species’ distribution. Herein, we systematically sampled 197 Gopher Tortoises for URTD across seven sites in south-central and south-eastern Alabama. Plasma samples were assayed for antibodies to M. agassizii and M. testudineum; nasal lavage samples were assayed for the presence of viable pathogens as well as pathogen DNA. Lastly, animals were scored for the presence of external symptoms and nasal scarring consistent with URTD. External symptoms of URTD were present in G. polyphemus in all sites sampled in Alabama. There was no relationship between active symptoms of URTD and Mycoplasma antibodies, however the presence of URTD nasal scarring was positively related to M. agassizii antibodies (P = 0.032). For a single site that was sampled in three sequential years, seroprevalence to M. agassizii significantly varied among years (P < 0.0001). Mycoplasma agassizii DNA was isolated from four of the seven sites using quantitative PCR, yet none of the samples were culture positive for either of the pathogens. An analysis of disease status and condition indicated that there was a significant, positive relationship between the severity of URTD symptoms and relative body mass (P < 0.05). This study highlights the need for continued monitoring of disease in wild populations. Specifically, focus must be placed on identifying other likely pathogens and relevant biomarkers that may be important drivers of URTD in North American tortoises. Special consideration should be given to environmental contexts that may render wild populations more susceptible to disease. [ABSTRACT FROM AUTHOR]

Highlights • Open pine woodlands provide habitat for a suite of wildlife species of concern. • Existing guidelines for vegetation structure to benefit these species were tested. • We used wildlife data for 17 species to develop models for comparison to guidelines. • Existing guidelines for herbaceous and canopy cover could be expanded. • Expanded guidelines increase management flexibility while still benefitting wildlife. Abstract Open pine ecosystems of the southern United States are a conservation priority for many agencies, organizations, and private landowners. These woodlands, characterized by moderately-stocked overstories, low cover of midstory, and grass-dominated herbaceous groundcover, provide important habitat for a suite of rare and declining wildlife species. To provide guidance for land managers engaged in habitat restoration in open pine ecosystems, ranges of desired conditions for elements of vegetation structure have been developed using literature survey and expert opinion. We compared empirical data on habitat occupancy for 17 wildlife species from second-growth longleaf pine woodlands in southwestern Georgia with recommended ranges for basal area (BA) of all pine, BA of pine ≥ 35.5 cm dbh, percent canopy cover, percent herbaceous cover, and percent shrub cover. Vegetation data were taken from 864 monitoring plots and Mahalanobis distance models were used to develop habitat suitability indices from the wildlife data. Recommendations for shrub cover and BA of pines ≥ 35.5 cm fit well with model predictions for all wildlife species. However, mean BA of all pines at sites used by wildlife were at the low end of the recommended range. Herbaceous cover at sites used by wildlife was well below the recommended range, whereas canopy cover was well above recommendations, suggesting these ranges should be expanded. These modifications could provide managers of open pine ecosystems greater flexibility, allowing them to incorporate a broader suite of objectives in their management while still providing habitat for wildlife species of concern. Moreover, our models suggest that monitoring presence of open pine indicator bird species may be an efficient method to assess restoration or management progress of open canopy pine systems. [ABSTRACT FROM AUTHOR]

Gopher tortoises ( Gopherus polyphemus) are candidates for range-wide listing as threatened under the U.S. Endangered Species Act. Reliable population estimates are important to inform policy and management for recovery of the species. Line transect distance sampling has been adopted as the preferred method to estimate population size. However, when tortoise density is low, it can be challenging to obtain enough tortoise observations to reliably estimate the probability of detection, a vital component of the method. We suggest a modification to the method based on counting usable tortoise burrows (more abundant than tortoises) and separately accounting for the proportion of burrows occupied by tortoises. The increased sample size of burrows can outweigh the additional uncertainty induced by the need to account for the proportion of burrows occupied. We demonstrate the method using surveys conducted within a 13,118-ha portion of the Gopher Tortoise Habitat Management Unit at Fort Gordon Army Installation, Georgia. We used a systematic random design to obtain more precise estimates, using a newly developed systematic variance estimator. Individual transects had a spatially efficient design (pseudocircuits), which greatly improved sampling efficiency on this large site. Estimated burrow density was 0.091 ± 0.011 burrows/ha (CV = 12.6%, 95% CI = 0.071-0.116), with 25% of burrows occupied by a tortoise (CV = 14.4%), yielding a tortoise density of 0.023 ± 0.004 tortoise/ha (CV = 19.0%, 95% CI = 0.016-0.033) and a population estimate of 297 tortoises (95% CI = 210-433). These techniques are applicable to other studies and species. Surveying burrows or nests, rather than animals, can produce more reliable estimates when it leads to a significantly larger sample of detections and when the occupancy status can reliably be ascertained. Systematic line transect survey designs give better precision and are practical to implement and analyze. [ABSTRACT FROM AUTHOR]

The article discusses the influence of landscape-level on terrestial snake occupancy within the southeastern U.S. The study uses occupancy modeling to identify habitat variables that affect in determining the presence of a particular species. Results show that some species were positively associated with scrub or shrub and grassland like Slowinski's cornsnake (Elaphe slowinskii), while copperhead snake and eastern diamond-backed rattlesnake were positively associated with forested habitats.

Gopher tortoise, Gopherus polyphemus, populations are threatened by habitat loss across their range. Management and conservation of the species has been hindered by the lack of population monitoring data. Recent studies have demonstrated that line transect distance sampling (LTDS) is efficient for estimating population parameters for gopher tortoises, yet this method has not gained wide-spread acceptance. We attempted to use LTDS to survey gopher tortoise populations on 20 protected areas across southern Georgia, USA in 2007 and 2008. We used a camera system to determine burrow occupancy at each site. The survey data were used to compare population estimates derived using LTDS (with burrow scoping) to estimates obtained with survey methods recommended in the 2007 Florida Gopher Tortoise Management Plan: area-constrained surveys of 15% of suitable habitat and a standard 50% burrow occupancy. LTDS estimates of tortoise population density ranged from 0.21 ± 0.04 tortoises/ha at Ohoopee Dunes Natural Area to 1.65 ± 0.37 tortoises/ha at General Coffee State Park. Distance sampling was generally very efficient (on average our survey rate was 0.88 km/h) and we obtained estimates of population size and density at 13 of the 20 sites. The method was much less efficient at sites with extremely low tortoise densities, and at sites where the survey area was poorly defined. Under the former circumstance, LTDS sampling would have required 88-1318 km of transect per site, which was beyond the scope of our overall project. In the latter circumstance additional ground-truthing of the habitat would have been necessary. Hence, we reported only the tortoise encounter rate and burrow occupancy estimates for these sites. Population estimates obtained with area-constrained surveys and a 50% burrow occupancy rate differed by as much as 114% from those obtained with LTDS and occupancy estimates based on burrow scoping. [ABSTRACT FROM AUTHOR]

We compared the effectiveness of five amphibian sampling methods in nine isolated wetlands in Baker County, Georgia, USA. Overall, aquatic funnel traps yielded the most species, although the number detected using frogloggers (automated frog call recording devices), funnel traps, dipnetting, and PVC pipe refugia was not significantly different among sampling techniques. We detected the same median number of species with funnel traps and frogloggers as with all five methods combined. Methods varied widely in their detection probabilities for individual species and life stages. Species occupancy estimates were strongly affected by method choice. Our results suggest that a combination of methods and prolonged sampling periods are necessary to detect the large number of species present in southeastern isolated wetlands. We recommend that future amphibian surveys in these habitats use a combination of floating funnel traps, frogloggers, and crayfish traps as sampling methods when an assessment of species richness is the objective of a study. [ABSTRACT FROM AUTHOR]

Because of high numbers of animals killed on Paynes Prairie State Preserve, Alachua County, Florida, the Florida Department of Transportation constructed a barrier wall-culvert system to reduce wildlife mortality yet allow for passage of some animals across the highway. During a one year study following construction, we counted only 158 animals, excluding hylid treefrogs, killed in the same area where 2411 road kills were recorded in the 12 months prior to the construction of the barrier wall-culvert system. Within the survey area lying directly in Paynes Prairie basin, mortality was reduced 65% if hylid treefrogs are included, and 93.5% with hylid treefrogs excluded. Sixty-four percent of the wildlife kills observed along the barrier wall-culvert system occurred at a maintenance road access point and along 300 m of type-A fence bordering private property. The 24 h kill rate during the post-construction survey was 4.9 compared with 13.5 during the pre-construction survey. We counted 1891 dead vertebrates within the entire area surveyed, including the ecotone between the surrounding uplands and prairie basin which did not include the barrier wall and culverts. Approximately 73% of the nonhylid road kills occurred in the 400 m section of road beyond the extent of the barrier wall-culvert system. We detected 51 vertebrate species, including 9 fish, using the 8 culverts after the construction of the barrier wall-culvert system, compared with 28 vertebrate species in the 4 existing culverts prior to construction. Capture success in culverts increased 10-fold from the pre-construction survey to the post-construction survey. Barrier wall trespass was facilitated by overhanging vegetation, maintenance road access, and by the use of the type-A fence. Additional problems resulted from siltation, water holes, and human access. These problems could be corrected using design modifications and by routine, periodic maintenance. [Copyright &y& Elsevier]