Year of Award
2024
Document Type
Thesis
Degree Type
Master of Science (MS)
Degree Name
Wildlife Biology
Department or School/College
Wildlife Biology Program
Committee Chair
Dr. L. Scott Mills
Commitee Members
Dr. Douglas J. Emlen, Dr. Joshua J. Millspaugh
Keywords
Predator-prey, behavioral plasticity, climate mismatch, snowshoe hare
Publisher
University of Montana
Subject Categories
Behavior and Ethology
Abstract
Climate change effects on predator-prey interactions are complex and poorly understood, with few study systems that explicitly connect specific antipredator traits to particular climate drivers. Such a system can be found in seasonal coat color change, whereby 21 species globally molt from a summer brown to a winter white coat to maintain camouflage with seasonal snow. Snowshoe hares (Lepus americanus) contend with increased predation due to climate-change induced coat color mismatch under decreasing snowcover. Through a combination of field experiments in the central Cascade mountains, my thesis investigates snowshoe hare mismatch and predation risk from both a predator and prey’s perspective. We developed collaborations with falconers to observe predator and prey behavior in simulated predatory encounters on a wild polymorphic population of polyphenic winter white and invariant brown morph snowshoe hares. In Chapter 1 we use measurements of flight initiation distance, concealment, and escape decisions in experiments using trained goshawks (Accipiter atricapillus) and hunting dogs (Canis familiaris) to investigate behavioral plasticity in hare escape behavior in response to predator functional group, and to camouflage mismatch. Hares exhibited behavioral plasticity in escape behavior in relation to predator type, utilizing subsurface refugia more often in encounters with aerial predators compared to terrestrial predators. We find no behavioral difference between color morphs and a lack of behavioral plasticity to mitigate mismatch, suggesting that mismatch-induced selection has not yet driven changes in hare behavior. In Chapter 2, we address mismatch through predators’ eyes. Using trained goshawks, we investigate raptor perception in relation to mismatch, movement, and habitat by evaluating attack distances on rabbit fur lures and model hares. We find that mismatch influences raptor detection of stationary models, but not moving lures. Greater attack distances in open habitats compared to forest reflect habitat effects on raptor prey detection. Mismatch with substrate color significantly increased detectability of white hare models, but not brown hare models, which may imply fitness differences for morphs of seasonally polyphenic species under future climate scenarios. This work improves our understanding of mismatch effects on predation risk for seasonally polyphenic prey as well as our understanding of snowshoe hare capacity to adjust their behavior in response to predation risk, highlighting the limitations of wildlife adaptation to rapid environmental change.
Recommended Citation
Emmel, Amanda Shuler, "The Hare and The Hawk: Predator, Prey, and Coat Color Mismatch in a Polymorphic Snowshoe Hare Population" (2024). Graduate Student Theses, Dissertations, & Professional Papers. 12344.
https://scholarworks.umt.edu/etd/12344
© Copyright 2024 Amanda Shuler Emmel