Breeding Migrations in Crawfish Frogs (Lithobates areolatus): Long-Distance Movements, Burrow Philopatry, and Mortality in a Near-Threatened Species

Abstract

Movements are risky behaviors to animals, and amphibians are no exception, yet most species of amphibians exhibit cyclic annual movements. Crawfish Frogs (Lithobates areolatus) are a relatively understudied species of North American amphibian considered to be “Near Threatened” globally. To better understand the biology of this species, and in particular to assess the role that movements play in affecting survivorship, we radio tracked 48 Crawfish Frog adults in 2009–2010. Our study encompassed a total of 7,898 telemetered-frog days; individual frogs were tracked for up to 606 days. These data demonstrate two behaviors previously undocumented in this species: 1) migration distances that averaged nearly 0.5 km, and for one frog was approximately 1.2 km; and 2) philopatry to upland burrows excavated by crayfish. Together, these findings indicate that Crawfish Frogs have a remarkable ability to home to distant upland burrow sites. Burrow fidelity in Crawfish Frogs involves, in part, following similar migration routes to and from breeding wetlands. Burrow fidelity also occurs after ranging movements, and again often involves individual frogs following the same circuit across years. We demonstrate that movements are hazardous for Crawfish Frogs (about 12 times riskier than burrow dwelling), and therefore have survival consequences. Our data further suggest that adult Crawfish Frogs are not typically moving long distances from one upland burrow to another to populate new sites; instead two mechanisms—adults varying breeding wetlands across years and juvenile dispersion—are primarily responsible for the colonization of new habitats.