Meeting Abstract
4.3 Monday, Jan. 4 Offspring growth and functional performance in Orange-crowed Warblers: a comparison between populations that differ in life-history strategies SOFAER, H.R.*; SILLETT, T.S.; GHALAMBOR, C.K.; Colorado State University; Smithsonian Migratory Bird Center; Colorado State University helen@lamar.colostate.edu
The evolution of parental investment strategies is expected to depend on parental residual reproductive value as well as on the relationship between parental care and offspring fitness. However, life history theory has been poorly integrated into the study of the growth and developmental rates of species whose offspring are entirely dependent on parental care. In passerine birds, few studies have related parental investment with offspring growth rates, or asked how this relationship may vary between populations with different life history strategies. In addition, although nestling mass has been positively correlated with future fitness, studies have not related mass to functional performance in fledglings. Here, we compare the nestling feeding and growth rates in two populations of Orange-crowned Warblers (Vermivora celata) that differ in their life history strategies, and ask how parental behavior and offspring mass may affect offspring mobility. We use a novel method to measure offspring functional performance, by quantifying the distance nestlings and fledglings can jump from a perch. Our results show a positive correlation between jumping distance and offspring mass, providing the first data linking mass to performance in passerine fledglings. Interestingly, our data also show that although per-nestling provisioning rates are higher in the population with the slower life history, nestlings in the population with the faster life-history strategy grow more quickly. These results support the hypothesis that there may be a trade-off between offspring quality and quantity within a single passerine species, and suggest that there may be costs to rapid growth even within altricial birds.
