Alyssa Borowske

PhD Candidate, University of Connecticut

Ecology and Evolutionary Biology

 

 

The aim of my dissertation is to consider ways in which events and processes within the annual cycle of migrant birds differ between the sexes within a species, and between species with different breeding systems.  While closely related and with overlapping habitat requirements, saltmarsh and seaside sparrows have distinct strategies regarding territoriality, monogamy, and parental care. Specifically, saltmarsh sparrows are completely promiscuous, do not defend territories, and only females participate in parental duties, whereas seaside sparrows are socially monogamous, territorial, and both sexes participate in parental care. Through extensive mist-netting during the breeding period in Connecticut and the non-breeding (winter) period in the South-Eastern United States, I will use key comparisons between species, within each species (separated by sex), and across seasons to  investigate how differential life histories influence key components in the birds’ annual cycles: 1) the timing of migration and molt events, 2) differential migration patterns, and 3) within-season survival and body condition. Questions I will address in my dissertation include:

Timing of migration and molt events: Do male saltmarsh or seaside sparrows return to the breeding grounds earlier than conspecific females do? After the breeding season, do males of each species molt earlier and leave earlier than conspecific females? Do seaside sparrows molt and leave before saltmarsh sparrows?

Differential migration patterns: Is the over-wintering location (based on latitude) of individual birds influenced by the birds’ sex or size in either species?

Consequences: During the breeding season, are survival and body condition of saltmarsh and seaside sparrows correlated with reproductive effort? During the non-breeding period, are survival and body condition correlated with past reproductive effort? With current environmental conditions?