Conservation Of Turtles

Contributed Paper
ROOM: HCCC, Room 21
SESSION NUMBER: 77
 

8:10AM Why did the Turtle Cross the Campus? a Ten-Year Study of an Urban Turtle Metapopulation
Mark S. Mills; Jeremy Brown; Katie Lavelle; Teresa Phillips; Ashlyn Powers; Chris Watson; Darrin Welchert
Turtles are common residents of urban environments, living in park lagoons, golf course ponds, urban streams and rivers, and other aquatic and terrestrial habitats. Urban areas provide unique habitats and problems for wildlife, including turtles. Nine ponds of various sizes are located on the 740-acre campus of Missouri Western State University. We began trapping and marking turtles in campus ponds in 2008 as part of a series of undergraduate research projects. We have 457 captures of 194 marked turtles consisting of five native and one introduced species living in the campus ponds: Apalone spinifera, Chelydra serpentina, Chrysemys picta, Graptemys pseudogeographica, Trachemys scripta elegans, and T. scripta scripta (nonnative). Population size estimates for each pond ranged from 7-49 turtles. These ponds are small (< 1 ha) and vary greatly in depth and hydrology, with several ponds drying and refilling during the study. Pond fidelity seems high, with several turtles being captured multiple times in the same pond over 10 years (e.g., one slider has been captured 22 times in the same pond since 2009). However, at least 20 turtles moved among the campus ponds, crossing roads and potentially parking lots, traveling straight-line distances ranging from 133-890m. We have also documented one turtle moving from an off-campus pond to a campus pond, a distance of approximately 1500m. In addition to the population ecology of these turtles, we will discuss the unique problems faced by urban turtle populations.
8:30AM Life History and Demography of a Nesting Population of Leatherback Sea Turtles at St. Croix, U. S. Virgin Islands, 1992-2013
Bill Kendall; Kristen Pearson; Peter Dutton; Kelly Stewart; Claudia Lombard
Knowledge of the population dynamics of the endangered leatherback sea turtle (Dermochelys coriacea) is important to the conservation of this species. Adult females are important contributors to population growth, and the most accessible life stage to study. The nesting population of leatherbacks at Sandy Point NWR, at St. Croix, U. S. Virgin Islands, has been studied via a saturation tagging program, with the use of PIT tags beginning in 1992. We used captures of individual females from 1992 to 2013 to model population dynamics of adult females (nesters and total females), and annual survival and remigration probabilities. For each year we modeled arrival date, renesting probability, and clutch frequency. We partitioned captures into neophytes and remigrants. We hypothesized a transient effect on neophyte survival, and that remigration probability and clutch frequency would be lower for neophytes. In addition, we hypothesized an increase in remigration probability with each successive year breeding was skipped. We found that the increase in population size in the 1990’s stabilized beginning in 2000, at >500 turtles, with the proportion of females nesting in a given year at an average of 0.43. The most parsimonious model included constant survival rate of 0.90, whereas apparent survival for neophytes was 0.82, indicating a transient effect. Remigration probability fluctuated but without trend. Nesting in two consecutive years was rare. Evidence for remigration probability increasing with successive skipped breeding was weak. However, remigration probability was substantially greater for remigrants than for neophytes. The same was true for clutch frequency, and neophytes arrived later than remigrants. Probability of capture at least once in a season was close to 1.0. These results support improving status of leatherbacks in the Caribbean, and given their nesting beach is protected, this study provides a benchmark for survival of adult female leatherbacks.
8:50AM Spotted Turtle Movement and Occupancy Dynamics Across an Urbanized Landscape
Ellery V. Ruther; Brett A. Degregorio; Jinelle H. Sperry
Wetland ecosystems are often both spatially and temporally variable, causing wildlife to utilize several different wetlands across a season, and therefore characteristics such as wetland quality and connectivity are likely to influence demographic processes. The ecology of semi-aquatic freshwater turtles makes them especially vulnerable to habitat fragmentation, because individuals often make long distance movements among a variety of habitats for mating, foraging, aestivating, and overwintering purposes. I investigated the movement patterns and occupancy dynamics of the spotted turtle (Clemmys guttata) in a highly urbanized landscape in northern Virginia. I radio-located 30 adult and 10 juvenile turtles across the active season (March-August) in 2017 and 2018. I used daily movements and home range sizes (autocorrelated kernel density estimates) as response variables in generalized linear mixed models and tested for effects of sex, age, climatic, and landscape features, as well as interactions among these. I also examined the occupancy dynamics of wetland patches using the same covariates. Juvenile turtles exhibited smaller daily movement and home range sizes than adult turtles. Turtle movement was strongly associated with precipitation and wetland depth, and home range size had an inverse relationship with road density. Road crossing frequency was correlated with precipitation, with no apparent influence from age or sex class. Variation in occupancy probability was best explained by climatic covariates, rather than habitat quality. This may be a function of the limited wetland availability, therefore forcing turtles to occupy sub-optimal patches. Because spotted turtles are equally dependent on both aquatic and terrestrial habitats, and may make large movements between wetland patches, it is recommended that this species should be managed using a landscape conservation approach. Further, conservation of wetland matrices and the connectivity among them, rather than individual patches, is vital for the population stability of this species and other sympatric semi-aquatic wildlife.
9:10AM Activity and Movement of Free-Living Box Turtles Are Largely Independent of Ambient and Thermal Conditions
Adam F. Parlin; Jessica A. Nardone; John Kelly Dougherty; Mimi Rebein; Kamran Safi; Paul J. Schaeffer
Ectotherms depend on ambient conditions for maintenance of physiological functions that in turn influence navigation, extent of movement, and thus habitat use. However, many studies that investigate thermal performance of movement are laboratory experiments that may not reflect patterns and processes observed in the field. We were interested in the thermal dependence of movement in the field for Eastern box turtles (Terrapene carolina carolina) and how related movement and activity were dependent on ambient conditions. Our study focused on the intensity of activity (from acceleration data) and extent of movement (from GPS and thread trailing data) of box turtles in a fragmented landscape near their northern population limit. First, we quantified the thermal performance curve of box turtles using activity as a measure of performance. Second, we investigated ecological factors that could influence activity and movement and characterized the movement as extensive (exploration) and intensive (foraging). In contrast to previous lab work investigating effects of temperature on activity, we found no relationship between box turtle activity and temperature in the field. Furthermore, box turtle activity was consistent over a wide range of temperatures. Cluster analysis categorized movement recorded with GPS more as intensive than as extensive, while thread trailing had more movement categorized as extensive than intensive – possibly altering interpretation of foraging and exploration. Box turtle activity was higher during the morning hours and began to decrease as the day progressed, concurrent with natural history studies. Activity and movement were nearly independent of environmental conditions, which supports the overall interpretation that turtle performance is that of a broad environmental generalist. More information on the resolution needed to definitively identify foraging and exploratory behavior in turtles is needed. Future studies of movement of other turtle and reptile species are needed to determine the generality of these findings.
9:30AM Visual and Olfactory Cues Raccoons Use to Find Diamondback Terrapin Nests: Do Raccoons Learn?
Rebecca A. Czaja; Sarah E. Edmunds; Christine N. Kasparov; Jae Byeok Yoon; Alexandra K. Kanonik; Russell L. Burke
As is true for many North American turtles, nest predation by Raccoons (Procyon lotor) is the significant cause of mortality of Diamondback Terrapin (Malaclemys terrapin) eggs at Jamaica Bay, New York. In addition to natural cues left by terrapins, conservation practices since 1998 have included marking terrapin nests with conspicuous vinyl flags, potentially adding an artificial cue. We used artificial nests to test whether more than a decade of subsequent field work at the same site resulted in a change in raccoon behavior. We replicated previous experiments by constructing the same nine artificial nest treatments and adding four new treatments. We also investigated the effect of soil disturbance itself using geosmin, a pungent, organic compound produced by Actinobacteria. We further tested whether detection of natural cues was affected by rainfall, using both artificial and natural terrapin nests. Our initial research using artificial nests at this site indicated that marking nests with flags did not increase predation rates, that raccoons located nests based on soil disturbance and ocean water scent, and raccoons were repelled by human scent. Currently, flag markers are still not important cues for raccoons locating terrapin nests, but ocean water scent no longer increases raccoon predation, and human scent no longer repels raccoons. Geosmin increased predation rates. We found that predation rates on natural and artificial nests were inversely correlated with the amount of rain on the day nests were laid/constructed, and heavy rainfall the evening after a nest is laid can dramatically reduce predation rates. These results indicate that raccoons in Jamaica Bay continue to locate nests primarily by relying on the tactile cue of soil disturbance rather than visual markers, moisture, or olfactory cues, and that selection may favor turtles that nest soon before heavy rainfall, which mask those cues.

 

Contributed Paper
Location: Huntington Convention Center of Cleveland Date: October 11, 2018 Time: 8:10 am - 9:50 am