Date of Award


Access Control

Open Access

Degree Name

Biology, M.A.


Biology Department


Amy M. McMillan, Ph.D., Associate Professor of Biology

Department Home page

First Reader

Amy M. McMillan, Ph.D., Associate Professor of Biology

Second Reader

Christopher M. Pennuto, Ph.D., Professor of Biology

Third Reader

Robert J. Warren II, Ph.D., Assistant Professor of Biology


Invasive species threaten global biodiversity via mechanisms that include altering the dynamics and structure of native food webs. Whereas much research has focused on how exotic species respond to native predators, less is known about how native predators are affected by invasive prey. Here I investigate the response of a rare and threatened native predator—the Eastern Hellbender (Cryptobranchus alleganiensis) to a high-profile invasive crayfish species, Orconectes rusticus. Hellbenders have declined throughout much of their range, and although the potential for exotic predators (i.e. sport fish) to negatively impact C. alleganiensis has been addressed, effects of exotic prey on hellbender populations are unknown. Crayfish are an important food resource for C. alleganiensis; however, some speculate the large and aggressive O. rusticus may be unpalatable to hellbenders in regions where these species have not historically co-occurred. The primary objective of this study was to determine how C. alleganiensis responds to a native prey species (Orconectes obscurus), relative to an exotic prey species (O. rusticus). Specifically, I tested to see if hellbenders discriminated between crayfish species using chemoreception, then I analyzed behavioral interactions among hellbenders and crayfish during video-recorded trials, and lastly, I assessed hellbender selectivity of crayfish prey during overnight feeding trials. Cryptobranchus alleganiensis generally showed a preference for the scent of native crayfish, and were more likely to strike at native crayfish. However, more invasive crayfish were consumed during overnight feeding trials. This discrepancy apparently results from differences in avoidance behavior between prey species; native crayfish (O. obscurus) exhibited superior avoidance abilities relative to the exotic O. rusticus. Thus, during biotic invasions, food preferences of native predators may be superseded by differences in antipredator behavior of prey.