Date of Completion

8-20-2015

Embargo Period

2-15-2016

Keywords

Annual cycle, body condition, carry-over effect, life history, migration, reproductive investment, survival, Saltmarsh Sparrow, Seaside Sparrow

Major Advisor

Chris Elphick

Associate Advisor

Eldridge Adams

Associate Advisor

Kent Holsinger

Associate Advisor

Robin Chazdon

Associate Advisor

Mike Willig

Field of Study

Ecology and Evolutionary Biology

Degree

Doctor of Philosophy

Open Access

Open Access

Abstract

I investigated ways in which events and processes within the annual cycle of migratory birds differ between the sexes of individual species, and between two closely-related species with different breeding systems. Specifically, I compared male and female Saltmarsh Sparrows (Ammodramus caudacutus), which are highly promiscuous, non-territorial, and have female-only care, and Seaside Sparrows (A. maritimus), which are socially monogamous, territorial, and have bi-parental care, to investigate how differential life histories influence: 1) the timing of migration and molt events; 2) feather quality and condition throughout the year; 3) within-season body condition and survival during summer and winter; and 4) migration patterns. The most significant conclusions were: 1) early male arrival to the breeding grounds may occur for different reasons in different species; 2) reproductive investment can delay pre-basic molt and migratory departure and reduce molt rate; 3) most feather damage occurs in the breeding season and can be influenced by a bird’s reproductive status and investment; 4) reproductive investment can lead to poor body condition that carries over into the winter, but condition differences do not necessarily translate into survival differences; 5) early male arrival may not correspond with sex-based latitudinal segregation on the wintering grounds, and 6) extensive banding efforts imply low connectivity between breeding and wintering sites in Saltmarsh Sparrows. Together, these results suggest that breeding strategies influence the performance of individuals throughout the annual cycle, and, while parental care can be costly, indirect forms of reproductive investment are costly too.

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