Habitat selection and movement behavior of Chiricahua leopard frogs

Abstract

Degradation of habitat and disruption of dispersal are major drivers of amphibian declines, including that of the Chiricahua leopard frog (Lithobates chiricahuensis). Currently, the Chiricahua leopard frog is federally threatened and restricted to anthropogenic sources of water, including ponds maintained for livestock, throughout much of its range. Habitat selection and patterns of dispersal between disjunct water sources are not well understood for this species. We captured frogs leaving ponds using pitfall traps and attached radio transmitters to frogs on the Ladder Ranch in southern New Mexico during summers 2013 and 2014. We checked pitfall traps and located telemetered frogs daily for up to 8 weeks. We assessed cues affecting the number of frogs emigrating from ponds using linear models, distances moved by frogs each day using linear mixed models, and finescale habitat selection using conditional logistic regression. Emigration of frogs from ponds was related to rainfall and was greatest at an intermediate level of rain. Daily movement distances were highly variable among individual frogs and not related to sex or size of the frog, which suggests that individual heterogeneity in dispersal behavior may be an adaptation of this species. We observed daily and total movement distances longer than any previously recorded for the species. Habitat selection was very consistent among individuals. Frogs chose habitats with more low-lying cover, a tree overstory, and a mud substrate, features created by summer monsoon rains. We suggest preservation and restoration of habitat features important for frogs and selecting translocation sites and times based on movement behavior observed in this study. Our findings will inform reintroductions of and habitat improvements for Chiricahua leopard frogs, with the eventual goal of delisting this species.