Monitoring coyote population dynamics with fecal DNA and spatial capture-recapture

Abstract

Estimating coyote (Canis latrans) density and other demographic parameters is difficult, particularly for populations that exist at low density. This is the situation for recently established coyote populations in the eastern United States where populations may be below carrying capacity and growth unregulated. We used non-invasive fecal DNA collected from 5 scat sampling sessions over 2.5 years to estimate population parameters (i.e., density, apparent survival, recruitment, and population growth) for coyotes at 2 different sites in the Ridge and Valley region of the central Appalachians in Virginia, USA. We identified individuals using microsatellite genotypes and estimated apparent survival for the local population at both sites across the 5 sessions in a single Cormack–Jolly–Seber model. We estimated density for each site and session separately using single session spatial replicates of 0.5-km transect segments as traps in a spatial capture–recapture model. Finally, we derived estimates of recruitment and population growth using an ad hoc robust design approach. We were able to estimate population parameters, even though coyote densities at both sites were low. Generally, derived recruitment and apparent survival were inversely related across sites, however, precision in estimates was poor. Thus, although there appeared to be some differences in demographic estimates for local coyote populations, uncertainty in parameters was too great to detect changes in demographic rates over short periods of time using ad hoc robust design. However, the non-invasive genetic sampling and spatial capture–recapture approach provides a useful methodology and framework for future research intended to estimate population dynamics for coyotes. This method will also be useful for other species that occur at low densities, over large spatial scales, and lack distinguishing marks for camera-trap surveys. Finally, we believe this method will allow for detection of population trends over greater periods of time, and we consider alternate sampling strategies and modeling approaches that may improve the ability to estimate demographic rates of change for coyote populations using noninvasive genetics and spatial capture–recapture. © 2016 The Wildlife Society.