SICB+ - Physiological costs of reproduction: A field experiment in female Barn Swallows McDermott, MT*; Madden, SA; Ayala, MJ; Zachary, ZM; Safran, RJ; MCDERMOTT, MOL; University of Colorado Boulder; University of California Davis; University of Colorado Boulder; University of Colorado Boulder; University of Colorado Boulder email@example.com
Reproduction and self-maintenance are energetically costly activities involved in classic life history trade-offs. However, few studies have experimentally manipulated these costs simultaneously in wild organisms to understand the physiological changes associated with increased reproductive and/or self-maintenance costs. In free-living female Barn Swallows (Hirundo rustica), we manipulated reproductive costs (by adding or removing chicks) and self-maintenance costs (by attaching a 1g GPS tag to half of our study birds) and measured changes in mass, immune status, stress hyperglycemia, and feather condition, as well as the likelihood of re-laying. GPS tags further allowed us to study the relationships between foraging behavior and physiological parameters. Tagged females exhibited signs of greater immune activation and were less likely to lay a second clutch, but our manipulations did not result in any other physiological changes. This experiment helps us to understand which physiological mechanisms may be involved in life history trade-offs in wild birds.