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Effects Of Eggshell Coloration On Egg Cannibalism Among Glaucous-Winged Gulls, Isabelle Hwang

Honors Theses

A common source of reproductive loss in gulls is egg cannibalism. At a large Glaucous-winged Gull (Larus glaucescens) colony on Protection Island, Washington, cannibalism accounts for 55% of egg loss. Because cannibalism is a form of predation and birds have a highly developed sense of vision, I hypothesized that visible light coloration of Glaucous-winged Gull eggs plays a role in determining whether they are cannibalized. I used logistic regression to test whether egg fate was related to egg brightness, specific coloration, specific spot coverage, coloration relative to the most common coloration, and spot coverage relative to the most common spot …