Date of Award

January 2021

Degree Type

Open Access Thesis

Document Type

Master Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

First Advisor

Stephen C. Richter

Department Affiliation

Biological Sciences

Second Advisor

Valerie E. Peters

Department Affiliation

Biological Sciences

Third Advisor

Cy L. Mott

Department Affiliation

Biological Sciences

Abstract

New evidence of active foraging by eastern copperheads, Agkistrodon contortrix, contradicts its description as an envenomation-reliant ambush predator. Evidence of active foraging through non-strike induced chemosensory searching (NSICS) was previously found in cottonmouths (A. piscivorus) but could not be replicated with A. contortrix in later experiments. I observed foraging methods similar to non-strike induced chemoreception when specifically predating upon cicada nymphs during seasonal emergences. I hypothesized that A. contortrix actively forage using chemoreception without envenomation, and that tongue flick rates would be higher during foraging behaviors than during non-predatory or resting behaviors. Behavior of twelve A. contortrix were filmed at a campsite in Kentucky during foraging excursions in the summer of 2020. Recordings were analyzed for tongue flick rates and presence or absence of seven behavioral activities. Each minute of recording was assigned to a behavioral category (ground movement, climbing, post-feeding movement, pausing, periscoping, eating, and fighting) based on the predominant behavior occurring within that minute and ecological context of the recording. We found statistically significant differences between tongue flick rates during predatory and non-predatory behaviors, differences among distinct foraging categories, and no differences in tongue flick rate between resting/non-chemoreceptive behaviors. We also identified significant differences in predatory movement behavior tongue flick rates of successful events of tracking cicadas to unsuccessful attempts. My results support the hypothesis that tongue flick rates in movement categories are elevated to levels expected with predatory chemoreceptive searching, even though A. contortrix did not envenomate prey items. Increases in tongue flick rates for trials that involved snakes encountering a cicada suggests that chemoreception is a discriminating factor for tracking cicada prey.

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