Genetic mark–recapture population estimation in black bears and issues of scale

Abstract

Abundance estimates for black bears (Ursus americanus) are important for effective management. Recently, DNA technology has resulted in widespread use of noninvasive, genetic capture–mark–recapture (CMR) approaches to estimate populations. Few studies have compared the genetic CMR methods to other estimation methods. We used genetic CMR to estimate the bear population at 2 study sites in northern New Hampshire (Pittsburg and Milan) in 2 consecutive years. We compared these estimates to those derived from traditional methods used by the New Hampshire Fish and Game Department (NHFG) using hunter harvest and mortality data. Density estimates produced with genetic CMR methods were similar both years and were comparable to those derived from traditional methods. In 2006, the estimated number of bears in Pittsburg was 79 (95% CI = 60–98) corresponding to a density of 15–24 (95% CI) bears/100 km2; the 2007 estimate was 83 (95% CI = 67–99; density = 16–24 bears/100 km2). In 2006, the estimated number of bears in Milan was 95 (95% CI = 74–117; density = 16–25 bears/100 km2); the 2007 estimate was 96 (95% CI = 77–114; density = 17–25 bears/100 km2). We found that genetic CMR methods were able to identify demographic variation at a local scale, including a strongly skewed sex ratio (2 M:1 F) in the Milan population. Genetic CMR is a useful tool for wildlife managers to monitor populations of local concern, where abundance or demographic characteristics may deviate from regional estimates. Future monitoring of the Milan population with genetic CMR is recommended to determine if the sex ratio bias continues, possibly warranting a change in local harvest regimes. © 2011 The Wildlife Society.

Black bear recolonization patterns in a human-dominated landscape vary based on housing: New insights from spatially explicit density models

“…Additionally, estimates of density at northern latitudes in CT (0.26 bears/km 2 ) were similar to established black bear populations in other parts of the species' range, such as upstate New York (0.2/km 2 ; Gardner et al, 2010), New Hampshire (0.15 -0.25;Coster et al, 2011), and Florida (0.12 -0.14; Dobey et al, 2005). This result, in combination with the support for a latitudinal trend, suggests that bear density may increase within central and southern latitudes in Connecticut, places that already receive many conflict reports.…”

Rapid growth and genetic diversity retention in an isolated reintroduced black bear population in the central appalachians

“…Black bears are elusive, cryptic, and occur at low density, which introduces difficulty in collecting demographic data (Mowat and Strobeck 2000, Coster et al ). As a result, live trapping often yields sample sizes too small for reasonably precise demographic estimates (Coster et al , Marucco et al ).…”

“…Black bears are elusive, cryptic, and occur at low density, which introduces difficulty in collecting demographic data (Mowat andStrobeck 2000, Coster et al 2011). As a result, live trapping often yields sample sizes too small for reasonably precise demographic estimates (Coster et al 2011, Marucco et al 2011. Non-invasive genetic capturemark-recapture (CMR) methods have become increasingly used among bear researchers and managers as practical and economic alternatives for estimating demographic and genetic characteristics of populations (Woods et al 1999, Waits and Paetkau 2005, Clark et al 2010).…”

The late-denning activities of the American black bear in Utah

“…These are very complex procedures, but such a rigorous approach may be beneficial for population monitoring (Garshelis and Hristienko 2006). Advancements have also been made in the use of noninvasive DNA sampling to estimate population abundance at local levels (e.g., Coster et al 2011, Peacock et al 2011, but cost or logistics of application at statewide levels may be prohibitive (Peacock et al 2011). The department is considering the incorporation of other techniques to supplement or replace current approaches as they become established and proven.…”