Meeting Abstract

P3.96  Wednesday, Jan. 6  Experimental addition of nest-dwelling bacteria influences antibody titers in nestling tree swallows, but not as expected. FORSMAN, A.M.*; ANGERT, E.R.; WINKLER, D.W.; Cornell University; Cornell University; Cornell University amf226@cornell.edu

Nestling birds already possess circulating antibodies at hatch because of maternally derived antibodies (MAb’s) transmitted via the egg yolk. MAb’s confer passive immune protection to nestlings and gradually degrade over the nestling period. Prior to egg-laying, females increase antibody production; and previous studies have demonstrated positive correlations among antibody titers in female circulation, egg yolk, and nestling circulation. In this study we tested the hypothesis that female deposition of yolk antibodies is influenced by bacterial prevalence in the nesting environment. We predicted that female tree swallows (Tachycineta bicolor) utilizing nestboxes with experimentally increased bacterial loads would lay eggs and produce nestlings with higher antibody titers than females nesting in boxes with decreased bacterial loads or control boxes. We manipulated bacterial load during nest building by either adding bacteria, isolated and cultured from old tree swallow nests, or by misting nests with 70% ethanol to slow bacterial growth. Control nests received no treatment. Contrary to our prediction, nestlings from nestboxes with added bacteria tended to have lower antibody titers than nestlings from control and ethanol treated nests. Unexpectedly this effect was more pronounced in older nestlings. Possible hypotheses explaining these data are discussed in addition to data on antibody titers in female circulation and egg yolk samples.