Date of Award

January 2020

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

Luke E. Dodd

Department Affiliation

Biological Sciences

Abstract

For many species, life history events are cyclical and often correspond to specific environmental conditions. As a result of environmental variability, the optimal conditions that regulate the range and activity of highly regulated cyclical organisms, like cicadas, are subject to temporal change. Variability in cicada emergence and abundance has been shown to impact the species that rely on the rapid influx of nutrients. One such predator is the Eastern Copperhead (Agkistrodon contortrix) that has been noted feeding on emerging cicadas throughout their range. In eastern Kentucky, observations of copperheads congregating to feed on cicadas has been documented in recreational areas. This creates an urgency to understand the driving factors of the timing of this relationship to reduce negative human-copperhead interactions. The objective of this research was to investigate variables (temperature, humidity, precipitation, moon phase, photoperiod, and growing-degree days) in connection with the timing of copperhead movement and cicada emergence. Nightly visual encounter surveys were conducted to determine copperhead and cicada relative abundances while observing behavioral interactions. Climatic data and environmental factors were collected during each survey or through the Midwestern Regional Climate Center and US Naval Observatory. Each year copperheads congregated consistently after the initial rush of cicada emergence with arrival fluctuating only a day across three years. The initial arrival of copperheads at the site was positively related to increases in growing degree day accumulation and cicada abundance. Increases throughout the season in copperhead abundance was positively associated with temperature, growing degree day accumulation, and cicada abundance. In contrast, initiation of cicada emergence was negatively related to temperature and relative humidity. This may be due to the pulsating nature or presence of a thermal minimum threshold for initial cicada emergence. Increased cicada abundance throughout the season was positively related to humidity and negatively related to moon phase. Higher humidity has often been associated with successful ecdysis of cicadas inferring more successful emergence on higher humidity nights. Overall, analyses suggest that cicada emergence at the site is a preemptive indicator of copperhead abundance, and growing degree day accumulation may have management implications for predicting copperhead arrival at foraging sites within the Daniel Boone National Forest.

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