Conservation and Ecology of Reptiles and Amphibians II

Contributed Paper
ROOM: Room 140 – Aztec
SESSION NUMBER: 89
 

10:30AM Combining Citizen Science and Traditional Research Reveals Trends in Northeastern Diamondback Terrapin Populations
Stephanie Egger; A. Brett Bragin; Barbara Brennessel; Michael Farina; Sandra J. Garren; Alexandra Kanonik; Drew P. McQuade; Noga Neeman; Charlotte B. Sornborger; John Wnek; Russell L. Burke
Conservation of wide-ranging species is especially difficult because the necessary population trend data are usually very difficult to collect in a robust manner. Thus, it is possible for species to undergo dramatic declines before region-wide or range-wide changes are detected. The diamondback terrapin (Malaclemys terrapin) inhabits ca. 6000 km of U.S. Atlantic and Gulf salt marshes and mangrove ecosystems from Massachusetts to Texas. Despite increased scientific and conservation interest in this species, terrapin population trend data are only available from a few small scale analyses and from qualitative surveys, hence their status is undetermined over much of their range. Here we combine long term mark-recapture data collected by citizen science and more traditional academically-based projects from nine terrapin populations in the northern portion of the terrapin range, spanning 16% of the species’ range. The sites differ in terms of conservation issues, by-catch in crab traps, road mortality, and local habitat loss. Also, conservation efforts such as nest protection and head-starting at some of these sites are predicted to lead to healthy populations. These studies have been conducted for multiple decades, so it is possible to distinguish short-term changes from long-term trends. We detected significant declines in three populations and more moderate declines at two more. There were overall significant increases in the number of nesting adults at two sites, but even these experienced dramatic declines in the last decade. We conclude that diamondback terrapins are extremely vulnerable in the northern portion of their range.
10:50AM Drought Affects Growth and Sex Ratio of Painted Turtles in a Long-Term Study in Nebraska
Larkin A. Powell; Ellen Dolph; Charrissa Zuerlein
Growth rates and population structure can provide insight into ecological dynamics, and long-term studies are useful to investigate the effects of climate on wildlife. We used a 12-year set of mark-recapture data collected from a population of painted turtles (Chrysemys picta) in a single pond near Ogallala, Nebraska during 2005-2016 to assess the variation in size structure and male-female ratio of the population and to parameterize a nonlinear growth model for males and females. Western Nebraska experienced two periods of drought during our study, which allowed us to determine impacts of climate conditions on turtle growth patterns and population structure. Our study pond maintained water levels during drought years. Male-female ratio in the sub-adult size class changed over time (proportion males range: 0.4-0.9), and we observed a lower proportion of males during more extreme drought years (Palmer Hydrologic Drought Index) than in non-drought years. In addition, males and females grew at slower rates during years with more extreme drought conditions, and our study suggests impacts of droughts to pond turtles in situations when ponds do not dry completely. Effects on female growth were more severe than effects on male growth, which has potential implications for reaching sexual maturity later during some scenarios for global climate change.
11:10AM Movements, Behaviors, and Response to Fire Events of Eastern Box Turtles in East Tennessee
Katie Harris; Craig Harper; Joseph Clark; Dwayne Elmore
Prescribed fire is an important management tool throughout the South. Effects of fire on vegetation and wildlife are well described in the literature for some communities and species, but less understood for others. Although the effects of fire continue to be investigated, relatively little is known about the effects of fire on the eastern box turtle (Terrapene carolina carolina). Very high frequency (VHF) transmitters were used to monitor box turtle mortality, movement, and habitat use in response to prescribed fire across three areas in east Tennessee. Turtles that did not experience fire had an average home range size of 2.46 ha ± 2.57 ha via minimum convex polygon analysis and an average daily movement of 7.8 m/day ± 4.0. Nine radiotagged turtles experienced late growing season-prescribed fire, of which no mortalities occurred. Turtles avoided mortality by occupying areas that did not burn, moving to unburned units, or by burrowing. Turtles exhibited high site fidelity and did not abandon their home range despite fire events. Carapace temperature did not exceed 35 °C for turtles in the burn units indicating that they did not come into contact with an active fire. Five turtles died as a result of a wildfire. Of the surviving 8 turtles, 4 directly experienced fire, while 4 did not. The turtles that directly experienced fire did not exhibit any injuries indicating that they burrowed in response to the fire. Subsequently, turtles in burned areas more frequently selected stumps as overwintering locations, whereas turtles in unburned areas more frequently overwintered in leaf litter when it was available. This research suggests that eastern box turtles may be physically and/or behaviorally adapted to lessen the direct effects of prescribed fire.
11:30AM Comparison of Survey Methods Enabling Estimates of Population Size and Population Demographics of Rio Grande Cooter
Ivana Mali; Adam Duarte; Dan H. Foley III; Michael R.J. Forstner
The Rio Grande Cooter (Pseudemys gorzugi) is a large riverine turtle occurring in New Mexico and Texas, United States. The species is listed as state threatened in New Mexico and of greatest conservation need in Texas. In fact, the United States Fish and Wildlife Service is currently reviewing its status for federal listing under U.S. Endangered Species Act. There is a paucity of information concerning the species’ population status, biology, ecology, and natural history. As a pilot study centered on filling in these information gaps, we assess two different methods for surveying this elusive species, traditional capture-mark-recapture sampling via baited hoop net traps and a less intense method by visual survey distance sampling. We then contrast the population demographics obtained from New Mexico locations with recently surveyed P. gorzugi in Texas. It seems distance sampling and capture-mark-recapture sampling result in similar estimates of population size. The comparative analysis uncovered fundamental differences in demographics between New Mexico and Texas. Turtles from Texas were significantly larger and had higher body condition indices. On the other hand, New Mexico location had a considerable proportion of hatchling turtles while Texas lacked both juvenile and hatchling turtles. The results provide the most recent estimates of population size for these locations and reveal important new findings regarding survey methodologies that could be useful for maintaining long-term monitoring programs. Additionally, it opens doors for further studies aimed at identifying the underlying causative factors creating the disparity between sampled locations in New Mexico and Texas.
11:50AM Nesting Location Determines Emergence Success of Eastern Box Turtle Hatchlings in a Heavily Altered Landscape
Tracy A. Melvin; Gary Roloff; Alicia Ihnken
Limited information exists on recruitment of eastern box turtles (Terrapene carolina carolina), a species of special concern, in landscapes heavily altered and used by humans. We documented nesting behavior and success in southwestern MI from 2013 – 2015 using radio telemetry on female turtles (n=34) and field surveys of nests (n=25) protected from predation. We modeled the relationships between: 1) clutch size and physical characteristics of the associated female, 2) number of eggs that showed development as a function of year and vegetation type that contained the nest, and 3) number of hatchlings that emerged from the nest by year and vegetation type. We found that turtles nested in a variety of vegetation types, including an abandoned gravel pit, grassland restoration sites, an active disk golf course, and agricultural fields. At the time of nesting, these vegetation types provided suitable nesting substrate with an open vegetation canopy. By the time hatchlings started to emerge, these habitats differed in vegetation cover, ranging from open to complete closure. We failed to find a significant effect of female physical characteristics on clutch size. We found no effect of year or habitat on the number of eggs that showed development, as defined as any sign of a neonate at any stage of development within or broken through its egg. We found a significant habitat effect on the number of hatchlings that emerged from the nest cavity. Although female box turtles used agricultural fields for nesting, those nests failed to produce any emergent hatchlings, although the eggs developed, suggesting that these fields serve as population sinks. Our results indicated that female physical characteristics were not reliable predictors of clutch size, and that habitat factors were the primary determinant of hatchling recruitment when depredation is not a factor.

 

Contributed Paper
Location: Albuquerque Convention Center Date: September 27, 2017 Time: 10:30 am - 12:10 pm