A methodology for long-term population monitoring of the endangered key largo cotton mouse

Abstract

The Key Largo cotton mouse (Peromyscus gossypinus allapaticola) was federally listed as Endangered in 1984 due to habitat loss and subsequent population decline, but because of infrequent monitoring, the extent of decline and long-term population trends are unknown. We modeled population abundance under a variety of trapping scenarios to develop a monitoring protocol that would provide accurate population estimates and could be conducted more frequently under current personnel and budget constraints. We captured cotton mice on 33 trapping grids in Key Largo, Florida, USA, during 3 trapping sessions (1 Mar-11 May, 4 Jul-7 Sep, and 29 Oct-31 Dec) in 2007. We compared demographic parameter estimates from subsets of trapping grids with estimates from all grids to identify a subset of grids that would produce population estimates within 10% and remain within the 95% confidence intervals of estimates using all grids when both methods were extrapolated to total available habitat. There were insufficient captures in session 1 to produce a reliable population estimate. We found that 13 and 12 trapping grids, respectively, produced abundance estimates meeting our criteria in sessions 2 and 3. We conclude that the subset of 12 grids trapped during November and December will allow a 64% reduction in number of trapping grids necessary to provide a reliable population estimate. Employed annually, our recommended trapping protocol provides state and federal agencies an efficient method for monitoring trends in the Key Largo cotton mouse population. Ó 2013 The Wildlife Society.

Evaluating nest supplementation as a recovery strategy for the endangered rodents of the Florida Keys

“…Key Largo cotton mice are susceptible to the same threats from exotic and native predators as woodrats, but their nest use across the refuge appears to be more dependent on habitat age. Occurrence models suggest that cotton mice are mostly restricted to mature hammock, which corresponds with previous research (USFWS ; Greene et al ). Current refuge restoration projects and preservation will provide additional cotton mouse habitat as the forests mature over the next several decades.…”

“…Relative to generalist woodrats, Key Largo cotton mice are habitat specialists and depend on mature hammock with deep leaf litter (Barbour & Humphrey ). Similarly to woodrats, statistically reliable estimates of cotton mouse abundance have been difficult to obtain, but the population trend is also declining (USFWS ; Greene et al ).…”

“…Historical data on the distribution and abundance of woodrats and cotton mice are sparse despite significant survey effort. This is most likely a consequence of the low detectability of the target species due to an apparent reduction in stick‐stacking behavior by the woodrats and low capture rates due to sampling designs based on various live trapping arrays (McCleery et al ; Potts et al ; Greene et al ). Camera traps provide a useful tool for sampling rare wildlife and can be used to generate strong inference (O'Connell et al ).…”

Are declines of an endangered mammal predation‐driven, and can a captive‐breeding and release program aid their recovery?

“…Each grid was trapped for four nights every 3 months, for a total of three sessions, from May 2005 to November 2005. The University of Georgia conducted another CMR study in 2007 on 34 grids with a 7 × 7 configuration and traps spaced 10 m apart (0.36 ha; Greene, Mengak & Castleberry, ). These grids were trapped every 4 months, for four nights, from March 2007 to December 2007.…”