Olfactory Mate Choice and Potential Chemical Signals of the White-Throated Sparrow (Zonotrichia albicollis)

Abstract

Chemical odor signals are well documented in mammals, and yet almost nothing is known about the use of chemical odor signals in birds due to the traditional view that birds have a no sense or a poor sense of smell. Recent studies have revealed the traditional view to be unfounded, but more work is necessary to 1) expand our knowledge of avian olfaction in passerine species and 2) determine whether birds utilize chemical signals. The aim of this thesis was to 1) test for olfactory-based choice in a passerine species, and examine the chemical composition of preen oil for potential chemical signals. Results suggest that the polymorphic white-throated sparrow does choose between odors from their own bedding and odors from fresh bedding based on their unique disassortative mating, with tan males and white females choosing fresh bedding over their own and white males and tan females choosing their own bedding over fresh bedding. Additionally, a study on captive white-throated sparrows found that multiple preen oil volatile compounds were seasonally elevated during the breeding season, and thus indicate the possibility of these compounds acting as chemical signals. In wild populations, preen oil composition varied by morph-sex classes as well as by year sampled, and some compounds may even change throughout the course of the breeding season. Comparisons between wild populations and captive birds indicate that captive conditions may also alter preen oil composition.