Graduation Year

2015

Graduation Month

May

Document Type

Thesis

Degree Name

Bachelor of Science

School or Department

Wildlife Biology

Major

Wildlife Biology – Terrestrial

Faculty Mentor

Erick Greene

Faculty Mentor Department

Biological Sciences, Division of

Keywords

mimicry, Amorpha juglandis, caterpillars, alarm calls, songbirds

Subject Categories

Behavior and Ethology | Ecology and Evolutionary Biology

Abstract

Caterpillar species possess a range of anti-predator defenses, from regurgitation to sonar jamming. The North American walnut sphinx caterpillar (Amorpha juglandis) produces a variety of whistling noises when pinched. Limited observations indicate that this causes avian predators to retreat, leaving the caterpillar alone. However, it is unknown why this whistle is such an effective deterrent. Interestingly, the A. juglandis whistle is acoustically similar to the “seet” alarm call that many bird species produce in response to their own predators. We propose that the A. juglandis whistle is a form of acoustic mimicry, in which the caterpillar protects itself by mimicking bird alarm calls. We tested this hypothesis by playing recordings of A. juglandis whistles, chickadee seet calls, and a control sound to flocks of small songbirds and comparing the birds’ responses to the different stimuli. Birds tended to freeze or dive for cover in response to the seet call and two types of caterpillar whistles. Our results suggest that these caterpillar whistles may protect caterpillars by mimicking the alarm calls of their avian predators.

Honors College Research Project

Yes

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© Copyright 2015 Jessica Lindsay