MEASURING FAT CONTENT USING COMPUTED TOMOGRAPHY TO ESTABLISH A BODY CONDITION INDEX IN FREE-RANGING BLANDING'S TURTLES (EMYDOIDEA BLANDINGII) IN ILLINOIS

Health assessment of free-ranging populations requires an integrated approach, often incorporating a method to measure mass as a representation of the animals' ability to utilize environmental resources. In chelonians, direct measurements of mass have historically served as a corollary for body condition. However, this method may not accurately represent the true fat volume (FV) and may be skewed by the presence of eggs, shell size, or muscle mass. The objective of this study was to use computed tomography (CT) to develop a model for determining body condition index (BCI) in free-ranging Blanding's turtles (Emydoidea blandingii). Mass, shell measurements, and FV were measured by CT in 65 free-ranging Blanding's turtles from Lake and DuPage counties in Illinois. Twenty-one different models were built for BCI using both FV and fat percentage (FP) as dependent variables. The best fit model for FP included the relationship between mass and carapace length with nearly 60% model support. The model for FV demonstrated a similar relationship but had only 18% support. Linear models with BCI as the dependent variable showed that juveniles had a higher FP than adults and females with more eggs had a lower FP. FP can be calculated in the field with nearly 60% accuracy compared to CT-assessed FP as a component of a physical exam and population health survey to assess the effectiveness of conservation efforts for the endangered Blanding's turtle.

EPIDEMIOLOGY OF EMYDOIDEA HERPESVIRUS 1 IN FREE-RANGING BLANDING'S TURTLES (EMYDOIDEA BLANDINGII) FROM ILLINOIS

Herpesvirus infections have been associated with high morbidity and mortality in populations of captive emydid chelonians worldwide, but novel herpesviruses have also recently been identified in apparently healthy free-ranging emydid populations. Blanding's turtle (Emydoidea blandingii), an endangered species in Illinois, has experienced range-wide declines because of habitat loss, degradation, and fragmentation. A novel herpesvirus, Emydoidea herpesvirus 1 (EBHV1), was identified in Blanding's turtles in DuPage County, IL, in 2015. Combined oral-cloacal swabs were collected from radio transmitter-fitted and trapped (n = 54) turtles multiple times over the 2016 activity season. In addition, swabs were collected at a single time point from trapped and incidentally captured (n = 84) Blanding's turtles in DuPage (n = 33) and Lake (n = 51) counties over the same field season. Each sample was tested for EBHV1 using quantitative polymerase chain reaction (qPCR). EBHV1 was detected in 15 adult females for an overall prevalence of 10.8% (n = 15/138; 95% confidence interval [CI]: 6.2-17.3%). In radio transmitter-fitted females, there was a significantly higher prevalence of EBHV1 DNA in May (23.8%, n = 10/42) than June (3.6%, n = 1/28), July (0%, n = 0/42), August (0%, n = 0/47), or September (7.7%, n = 3/39) (odds ratio: 12.19; 95% CI: 3.60-41.30). The peak in May corresponds to the onset of nesting and may be associated with increased physiologic demands. Furthermore, all positive turtles were qPCR negative in subsequent months. There were no clinical signs associated with EBHV1 detection. This investigation is the critical first step to characterizing the implications of EBHV1 for Blanding's turtle population health and identifying management changes that may improve sustainability.

Road avoidance and its energetic consequences for reptiles

Roads are one of the most widespread human-caused habitat modifications that can increase wildlife mortality rates and alter behavior. Roads can act as barriers with variable permeability to movement and can increase distances wildlife travel to access habitats. Movement is energetically costly, and avoidance of roads could therefore impact an animal's energy budget. We tested whether reptiles avoid roads or road crossings and explored whether the energetic consequences of road avoidance decreased individual fitness. Using telemetry data from Blanding's turtles (Emydoidea blandingii; 11,658 locations of 286 turtles from 15 sites) and eastern massasaugas (Sistrurus catenatus; 1,868 locations of 49 snakes from 3 sites), we compared frequency of observed road crossings and use of road-adjacent habitat by reptiles to expected frequencies based on simulated correlated random walks. Turtles and snakes did not avoid habitats near roads, but both species avoided road crossings. Compared with simulations, turtles made fewer crossings of paved roads with low speed limits and more crossings of paved roads with high speed limits. Snakes made fewer crossings of all road types than expected based on simulated paths. Turtles traveled longer daily distances when their home range contained roads, but the predicted energetic cost was negligible: substantially less than the cost of producing one egg. Snakes with roads in their home range did not travel further per day than snakes without roads in their home range. We found that turtles and snakes avoided crossing roads, but road avoidance is unlikely to impact fitness through energetic expenditures. Therefore, mortality from vehicle strikes remains the most significant impact of roads on reptile populations.

Relating annual increments of the endangered Blanding's turtle plastron growth to climate

This research is the first published study to report a relationship between climate variables and plastron growth increments of turtles, in this case the endangered Nova Scotia Blanding's turtle (Emydoidea blandingii). We used techniques and software common to the discipline of dendrochronology to successfully cross-date our growth increment data series, to detrend and average our series of 80 immature Blanding's turtles into one common chronology, and to seek correlations between the chronology and environmental temperature and precipitation variables. Our cross-dated chronology had a series intercorrelation of 0.441 (above 99% confidence interval), an average mean sensitivity of 0.293, and an average unfiltered autocorrelation of 0.377. Our master chronology represented increments from 1975 to 2007 (33 years), with index values ranging from a low of 0.688 in 2006 to a high of 1.303 in 1977. Univariate climate response function analysis on mean monthly air temperature and precipitation values revealed a positive correlation with the previous year's May temperature and current year's August temperature; a negative correlation with the previous year's October temperature; and no significant correlation with precipitation. These techniques for determining growth increment response to environmental variables should be applicable to other turtle species and merit further exploration.