An amphibian species of concern prefers breeding in active beaver ponds

Abstract

AbstractChanges in water availability threaten to reduce suitable habitat for wildlife in the western United States. Ecosystem engineers, such as beavers (Castor canadensis), potentially mitigate the effects of such habitat changes, particularly in stochastic environments. Our goal was to determine factors driving wetland use of a widespread, declining species, the northern leopard frog (Lithobates pipiens), in southeastern Wyoming. We evaluated hypotheses about habitat preferences of leopard frogs in a healthy population using occupancy modeling. Although leopard frogs may breed in a variety of wetlands, we found that the main drivers of breeding distribution in southeast Wyoming were the degree of beaver activity at wetlands and the ability of a site to retain water throughout the summer. In both years of our study (2012–2013), leopard frogs bred only in beaver ponds, with a preference for those ponds actively used by beavers. Leopard frogs also bred in wetlands that were less likely to dry over the course of the season. This effect was strongest in a dry year when water availability was limiting (2012), but still among the top drivers in the wetter year (2013). The decreased predictive power of water in a high snowpack year corresponded to an increase in the importance of wetland shape complexity, likely representative of breeding habitat availability along wetland edges. Identifying factors driving the distribution of healthy populations of species that are declining elsewhere can uncover limiting factors across the species’ range. We conclude that beavers are one vital conservation and management tool for maintaining declining populations of northern leopard frogs. While site‐level effects may vary, the presence of beaver ponds across the landscape in water‐limited systems, particularly in times of drought, should have positive impacts on many native amphibian species.