Meeting Abstract

P3-152   -   Effects of experimentally-induced asynchronous hatching on development in a songbird Stansberry, KR*; Kelly, TR; Couvillion, KE; Cannon, AL; Kittilson, JD; Heidinger, BJ; Lattin, CR; Louisiana State University; Louisiana State University; Louisiana State University; Louisiana State University; North Dakota State University; North Dakota State University; Louisiana State University kstans6@lsu.edu

Sibling competition for limited parental resources is found throughout the animal kingdom and is strongly affected by size differences among siblings. Many songbirds begin active incubation after laying their penultimate egg, which results in synchronous hatching of all but the last egg, and in nestlings of relatively equal size. However, later in the breeding season, broods may begin incubating as soon as an egg is laid because ambient temperatures exceed the minimum critical threshold for development, resulting in size hierarchies between siblings. To test the hypothesis that environmentally-induced incubation negatively impacts nestling development, I experimentally manipulated incubation temperature in nest boxes of free-living European starlings (Sturnus vulgaris) by placing heating packs beneath the nest cup during the egg lay period (n=10). In the control group (n=9), boxes were opened as in heated nests but no heating packs used. We collected morphological measurements and blood samples for telomere analysis at multiple time points post hatch to monitor potential trade-offs in nestling development. Preliminary results indicate heated boxes produced nestlings of smaller mass, wing length, and tarsus length during the first 9 days post-hatch. On day 12 post-hatch, nestlings from heated nests no longer differed from controls in mass, but retained smaller wing and tarsus lengths. Despite the difference in skeletal size between heated and control nests, telomere lengths did not differ between treatments 6 or 12 days post-hatch. These results suggest that nestlings in more asynchronously-hatched broods may compensate for reduced mass at a cost to skeletal structures during development at no cost to telomere length. Because climate change may increase rates of environmental incubation, trade-offs among different growth metrics may become increasingly common in altricial songbirds.