Effects of Vertical Transmission of Maternal Antibodies to Mycoplasma Gallisepticum on Growth and Condition of Eastern Bluebird Nestlings (Sialia Sialis)

Mothers display maternal effects to influence the development and success of offspring through processes such as resource allocation. In birds, this occurs largely through the egg yolk with the vertical transmission of antibodies to offspring to protect the vulnerable young from disease. Specifically, poultry and eastern bluebirds across the eastern United States are commonly infected by the bacteria Mycoplasma gallisepticum (MG), for which mothers may produce antibodies against. To test for the vertical transmission of MG-specific antibodies from mothers to nestlings in eastern bluebirds and the associated fitness effects, bluebird boxes were set up and monitored during the field season. Nests were sampled from over a span of 14 days, and growth measurements and blood samples were taken periodically from nestlings. The serum, taken from nestlings at 2 and 5 days old, was used to run direct enzyme linked immunosorbent assays (ELISAs). We compared nestlings who had and did not have antibodies, and we examined the effects of antibody concentration. A large proportion of adult females tested positive for MG-specific antibodies, and a small proportion of their chicks tested positive for those antibodies, confirming some vertical transmission. Nestlings that tested positive for MG antibodies had a greater change in tarsus length over the nestling period. Of these chicks that tested positive for antibodies, a greater amount of antibodies was associated with greater body condition on day 11. However, of the positive antibody nestlings, their antibodies were shown to have catabolized by day 5, suggesting that these do not last long and may simply be a byproduct of reproduction. Although the presence of antibodies had a positive effect on tarsus growth during the nestling period, the protective effects from MG antibodies are limited because of their quick degradation