Date of Completion
Annual cycle, body condition, carry-over effect, life history, migration, reproductive investment, survival, Saltmarsh Sparrow, Seaside Sparrow
Field of Study
Ecology and Evolutionary Biology
Doctor of Philosophy
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.
Borowske, Alyssa C., "Effects of Life History Strategies on Annual Events and Processes in the Lives of Tidal Marsh Sparrows" (2015). Doctoral Dissertations. 877.