Tidal marsh sparrows throughout the annual cycle
Saltmarsh and seaside sparrows are closely related, are both found exclusively in tidal marshes, and can even occur in the same marshes. Despite the similarities in habitat requirements, diet, and evolutionary histories, their breeding systems differ dramatically. Saltmarsh sparrows are completely promiscuous, do not defend territories, and only females build nets, incubate eggs, and care for the young. Seaside sparrows, however, have pair bonds, defend territories, and both sexes participate in parental care. Due to these differences in breeding strategies, male saltmarsh sparrows fall at one end of a reproductive investment continuum, while female saltmarsh sparrows fall at the opposite end, and male and female seaside sparrows are in the middle. In addition to determining which activities each class of bird engages in during the breeding season, these differences in reproductive involvement could have impacts on other aspects of the birds’ lives.
My field dissertation work consisted of spending as much time as possible with the birds. In the spring, I went out into the marsh in late April, as soon as the birds began returning to Connecticut to reproduce. I caught the sparrows in fine nets, banded each individual, took various measurements, photographed each bird’s wing and tail, and released the birds close to where they were caught. I continued this work through the breeding season and into the fall, until the local birds had left for the non-breeding grounds in the south-eastern USA. In December, I followed the sparrows in their migration, and set up a second field season in South Carolina, with forays into North Carolina, Georgia, and Florida.
Read more about my dissertation here.