Matthew J Goode | Search USGS

USGS2014

Capture-recapture of white-tailed deer using DNA from fecal pellet-groups

Traditional methods for estimating white-tailed deer population size and density are affected by behavioral biases, poor detection in densely forested areas, and invalid techniques for estimating effective trapping area. We evaluated a noninvasive method of capture—recapture for white-tailed deer (Odocoileus virginianus) density estimation using DNA extracted from fecal pellets as an individual marker and for gender determination, coupled with a spatial detection function to estimate density (spatially explicit capture—recapture, SECR). We collected pellet groups from 11 to 22 January 2010 at randomly selected sites within a 1-km2 area located on Arnold Air Force Base in Coffee and Franklin counties, Tennessee. We searched 703 10-m radius plots and collected 352 pellet-group samples from 197 plots over five two-day sampling intervals. Using only the freshest pellets we recorded 140 captures of 33 different animals (15M:18F). Male and female densities were 1.9 (SE = 0.8) and 3.8 (SE = 1.3) deer km-2, or a total density of 5.8 deer km-2 (14.9 deer mile-2). Population size was 20.8 (SE = 7.6) over a 360-ha area, and sex ratio was 1.0 M: 2.0 F (SE = 0.71). We found DNA sampling from pellet groups improved deer abundance, density and sex ratio estimates in contiguous landscapes which could be used to track responses to harvest or other management actions.

Tennessee↗

USGS2002

Natural history of a northern population of twin-spotted rattlesnakes, Crotalus pricei

The twin-spotted rattlesnake ( Crotalus pricei ) is a small-bodied pitviper that has received little attention in the literature to date. The species reaches the northern limit of its range in southeastern Arizona, where it inhabits higher elevations than any of the state's 10 other rattlesnake species. During 1997–2000, we captured, measured, and marked 127 C. pricei in Arizona's Chiricahua Mountains between 2530 and 2900 m elevation. We also used radiotelemetry to track the movements of 16 C. pricei in the study area during 1997–1998. Mean (± SE) snout–vent length of C. pricei was 387.8 ± 8.3 mm (range = 168–572), and mean mass was 53.5 ± 3.3 g (range = 3.6–188.5). Based on fecal analyses, lizards constituted the bulk of prey (74%), but the diet of C. pricei also included mammals, birds, and a conspecific. Mating was concentrated in August and early September and parturition took place during late July and August. Mean number of embryos was 3.94 ± 0.34 (range = 1–6) and female reproduction appeared biennial or less frequent. Based on shed and growth rates, female C. pricei develop embryos at 4–5 years of age. Gravid females maintained warmer body temperatures relative to substrate temperature than nongravid females or males, presumably by spending more time basking than other snakes. Radiotelemetry revealed that movement patterns varied from year to year, as males moved over six times farther per week during the 1998 monsoon season (July to September) than during the 1997 monsoon season. Additionally, use of talus slopes by males decreased during 1998. During dry years, such as 1998, males may be forced off talus into cooler microclimates where resources are less concentrated than on talus.

Journal of Herpetology↗