First demographic estimates for endangered Florida bonneted bats suggest year-round recruitment and low apparent survival

Abstract

Estimates of the demographic information necessary to project future population changes are lacking for the endangered Florida bonneted bat (Eumops floridanus). We conducted a mark-recapture study on a population of bonneted bats using bat houses on Babcock-Webb Wildlife Management Area, Charlotte County, Florida, United States. We captured 175 individuals during 6 capture events that recurred every 4 months between April 2014 and December 2015. We implanted passive integrated transponder tags in all captured individuals and used open population capture-recapture models to estimate apparent survival, recruitment, and population growth rates of this population. Key model assumptions were evaluated via simulation. Apparent survival estimates were lower than estimates for most other bat species. Juveniles had lower annual apparent survival (φ = 0.09 [95% confidence interval [CI]: 0.04-0.19]) than adults (φ = 0.46 [0.36-0.57]). Recruitment was constant between sexes and over time (f = 0.48 [0.23-0.75]). Apparent survival had a greater influence on population growth rates than did recruitment, indicating that low survival rates could lead to population declines. Models of population growth rates showed a stable to potentially declining population trend, although the trend was highly variable, with estimates ranging from large declines to increases (λ = 0.89 [0.65-1.22]). Any potential declines in the population may be more pronounced in adult females (λ = 0.8[0.58-1.13] compared to λ = 1.1[0.74-1.69] for males); however, the 95% CI of the population growth rate included 1, indicating a need for additional research to derive more precise estimates. This work represents the 1st estimates of demographic parameters of this endangered species.