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.

Integrating multiple genetic detection methods to estimate population density of social and territorial carnivores

“…Our laboratory analyses of hair and scat samples were nearly identical to those used by Ausband et al (2011) and Morin et al (2016), respectively. Briefly, we analyzed samples at the Laboratory for Ecological, Evolutionary and Conservation Genetics at University of Idaho (Moscow, Idaho, USA), which had facilities dedicated to analyzing low-quality, low-quantity DNA samples.…”

“…We first cleared all scat from all transects immediately prior to implementing sampling to equalize the expected baseline detection rates across sampling occasions (Morin et al 2016). We first cleared all scat from all transects immediately prior to implementing sampling to equalize the expected baseline detection rates across sampling occasions (Morin et al 2016).…”

“…Therefore, we discretized scat transects at 500-m intervals to create 264 scat detectors that were assigned the mean coordinates of each interval (Royle et al 2014, Morin et al 2016); this discretization distance was determined by sequentially reducing the resolution from 1000 m until the density estimate stabilized (estimates using 250-and 500-m intervals were nearly identical). Therefore, we discretized scat transects at 500-m intervals to create 264 scat detectors that were assigned the mean coordinates of each interval (Royle et al 2014, Morin et al 2016); this discretization distance was determined by sequentially reducing the resolution from 1000 m until the density estimate stabilized (estimates using 250-and 500-m intervals were nearly identical).…”

“…North American gray wolves (Canis lupus), Mexican gray wolves (C. l. baileyi), and red wolves (C. rufus) are federally endangered in parts of the United States, whereas coyotes (C. latrans) have expanded range and present a number of management challenges in both wildland and urban environments, including hybridization with wolves (Kays et al 2009, Bohling and. Both coyotes and wolves tend to be highly territorial and strategically defecate to mark and communicate territory extents to conspecifics (Rothman and Mech 1979, Gese and Ruff 1997, Barja and List 2014; therefore, collecting scat samples along travel routes or at rendezvous sites has proven effective , Morin et al 2016, Piaggio et al 2016, L opez-Bao et al 2018. Although camera trapping is perhaps the most widely used method for noninvasively detecting wildlife (Foster and Harmsen 2012), the lack of individually unique natural markings (e.g., pelage spotting or striping) on wolves, coyotes, and other canids typically precludes individual identification from photographs.…”

“…Noninvasive genetic sampling does have disadvantages, however, including DNA degradation in scat and hair samples that can reduce the total number of detections and spatial recaptures (Waits and Paetkau 2005, Long et al 2008, Morin et al 2016. Cohorts of a population may also have differential defecation rates, particularly at locations commonly used to mark and communicate territories among conspecifics.…”