Justine Fox

Project Title: Can Upland Clustering of Eastern Spadefoot Toads Predict Breeding Pool Locations?

Mentors: Anne Devon-Song and Dr. Nancy Karraker

Abstract: Eastern Spadefoot Toads (Scaphiopus holbrookii) are explosive breeders, migrating from their upland habitat to breed in ephemeral pools during heavy rain events. These small breeding pools are highly ephemeral and hence difficult to find, and there is no method to locate breeding pools without previous knowledge of their locations, or finding them on a breeding night. It is therefore likely that many breeding pools are undetected, which makes long-term monitoring of this species difficult. In a 2015 study conducted in Yorktown, VA, clustering of larger, sexually mature Eastern Spadefoot Toads was observed. We hypothesized that sexually mature toads cluster near breeding pools, and that these clusters can be used to locate breeding pools. We surveyed forest adjacent to ca. 9 km of roads for Eastern Spadefoot Toads in Yorktown, Virginia, and obtained GPS location and snout-vent length for each individual. We used these data to interpolate average size of toad across a 45 m buffer around surveyed roads, and determined the relationship between average toad size and distance to nearest breeding pool We discovered that clusters of large adults and small juveniles were more likely to be found within 100 m of breeding ponds than medium-sized toads, while the vast majority of medium-sized toads were found 100 – 1200 m away from breeding ponds. Upland clustering of both mature adults and small juveniles may be used to predict locations of ephemeral breeding pools.