Search

The accuracy of posttranslocation population monitoring methods is critical to assessing long-term success in translocation programs. Translocation can produce unique challenges to monitoring efforts; therefore, it is important to understand the flexibility and robustness of commonly used monitoring methods. In Florida, USA, thousands of gopher tortoises Gopherus polyphemus have been, and continue to be, translocated from development sites to permitted recipient sites. These recipient sites create a broad range of potential monitoring scenarios due to variability in soft-release strategies, habitat conditions, and population demographics. Line transect distance sampling is an effective method for monitoring natural tortoise populations, but it is currently untested for translocated populations. We therefore produced 3,024 individual-based, spatially explicit scenarios of translocated tortoise populations that differed in recipient site and tortoise population properties, based on real-world examples, literature review, and expert opinion. We virtually sampled simulated tortoise populations by using line transect distance sampling methods and built a Bayesian hierarchical model to estimate the population density for each simulation, which incorporated individual-level covariates (i.e., burrow width and burrow occupancy). Line transect distance sampling was largely appropriate for the conditions that typify gopher tortoise recipient sites, particularly when detection probability on the transect lines was greater than or equal to 0.85. Designing the layout of transects relative to the orientation of soft-release pens, to avoid possible sampling biases that lead to extreme outliers in estimates of tortoise densities, resulted in more accurate population estimates. We also suggest that use of individual-level covariates, applied using a Bayesian framework as demonstrated in our study, may improve the applicability of line transect distance sampling surveys in a variety of contexts and that simulation can be a powerful tool for assessing survey design in complex sampling situations. [ABSTRACT FROM AUTHOR]

The gopher frog Lithobates capito is one of the most terrestrial frogs in the southeastern United States and often inhabits gopher tortoise burrows Gopherus polyphemus outside of the breeding season. Gopher frog populations have declined, and the species is under review for listing as threatened or endangered under the U.S. Endangered Species Act. Much of our knowledge on the status of gopher frogs is based on detections of larvae at breeding wetlands, which can be challenging because of environmental variability and provides no information on the terrestrial life stages of the species. Therefore, an alternative method is called for. We recorded observations of gopher frogs during gopher tortoise surveys at four conservation lands in Florida and used line-transect distance sampling to estimate frog abundance. We also recorded burrow size, incidence of frog co-occupancy with tortoises, and distance from frog-occupied burrows to breeding wetlands. We observed 274 gopher frogs in 1,097 tortoise burrows at the four sites. The proportion of burrows occupied by gopher frogs among sites ranged from 0.17 to 0.25. Gopher frog abundance in tortoise burrows was 742 (512–1,076 95% CL) at Etoniah Creek State Forest, 465 (352–615) at Ft. White Wildlife Environmental Area, 411 (283–595) at Mike Roess Gold Head Branch State Park, and 134 (97–186) at Watermelon Pond Wildlife Environmental Area. We observed up to four frogs in a single burrow. The proportion of frogs detected in burrows occupied by a gopher tortoise ranged from 0.46 to 0.79 among sites, and overall, gopher frogs preferred burrows occupied by tortoises over unoccupied burrows (χ2 = 15.875; df = 3; P = 0.001). Gopher frogs used burrows from 7 to 43 cm in width; mean width of frog-occupied burrows did not differ from that of unoccupied burrows (F1,3 = 0.049, P = 0.825). Distance from frog-occupied tortoise burrows to the nearest breeding wetland ranged from 141 to 3,402 m. Our data on gopher frogs collected in conjunction with gopher tortoise monitoring efforts using line-transect distance sampling and burrow cameras provided novel information on frog abundance in their terrestrial habitat and required no additional effort. However, the extent to which frogs use tortoise burrows relative to other available refuges (small mammal burrows, stumps, or other structures) is unknown; thus, our estimates should be considered conservative. We suggest that terrestrial abundance estimates for gopher frogs can complement efforts to monitor breeding activity to provide a more comprehensive means of monitoring population trends in this cryptic species. [ABSTRACT FROM AUTHOR]

The article discusses a study of a small population of loggerhead musk turtles or Stenotherus minor in northwestern Florida. The researchers used goggling, a sampling method facilitated by the clear water of spring and spring habitats to study the loggerhead musk turtle. Goggling is reportedly efficient at detecting loggerhead musk turtles in riverine systems but should consider sampling-specific biases when making population-level inferences. The researchers note that failing to incorporate heterogeneity in detection probability will possibly bias abundance estimates.

• Frequent fire benefits many snake species found within mesic longleaf pine forests. • Most snake species occupied areas that had been burned within two years. • Frequent fire may provide basking and refugia sites and more foraging opportunities. Prescribed fire is an essential tool for the restoration and maintenance of the longleaf pine (Pinus palustris) ecosystem. This type of management benefits wildlife species that are frequently associated with open canopy pine forests in the Southeastern U.S., including upland snakes. But few studies have examined the long term effects of prescribed fire (i.e., fire frequency over time) on snake occurrences at local and landscape scales. Likewise, comprehensive data are lacking on the response of snakes to individual prescribed burns (i.e., how long after a fire does a snake occupy a location). To investigate snake responses to these two factors, we used radio-telemetry data for five species of snakes, including three species of open-canopied forest specialists and two species that occur more broadly in upland forests (i.e., generalists), on a large site managed with prescribed fire. We hypothesized that open-canopied forest specialists, eastern diamondback rattlesnake (Crotalus adamanteus), Florida pine snake (Pituophis melanoleucus), and eastern coachwhip (Coluber flagellum) would select more frequently burned locations over less frequently burned locations and would occupy locations sooner after a fire than generalist species, eastern kingsnake (Lampropeltis getula) and gray ratsnake (Pantherophis allegheniensis). We used spatial data collected from previous snake radio-telemetry studies conducted over a nine year period (2003–2012) and annual burn data from 1994 to 2012. We used compositional analysis to evaluate snake use (selection) versus availability of locations based on fire frequency at different spatial scales (home range and landscape). As predicted, open-canopied forest specialists selected locations with more frequent fire (≤2.5 y return interval) significantly more often than locations with less frequent fire (≥3.3 y return interval; F 7, 18 = 9.06, p < 0.0001). Whereas habitat generalists selected locations with fires across a broader spectrum of frequencies (every 2–10 y) significantly more often than locations that were not burned in 10 years (no burn) or those burned most frequently (1.4 y return interval; F 7, 21 = 5.94, p < 0.001). The three open-canopied forest specialists, as well as the generalist, eastern kingsnake, predominantly used locations within two years after a burn (eastern diamondback rattlesnake, 81% of locations; Florida pine snake, 91% of locations; eastern coachwhip, 98% of locations; and eastern kingsnake, 91% of locations. The generalist, grayrat snake, selected locations where time since burn was less than two years (53.8% of locations), as well as, locations that had not been burned in 10 years (23.5%). Our data suggest that forest management programs that include prescribed fire with short burn return intervals (<3 y) over long time periods would benefit both open-canopied forest specialists and generalist snake species that use open-canopied forests. [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]