P2.103 Thursday, Jan. 5 Growing up in the dark isn’t so bad: Development of cavity nesting bluebirds birds is not limited by vitamin D HOOD, Wendy R; Auburn University firstname.lastname@example.org
Cavity nesting birds have young that typically display slower growth rates than their open nesting counterparts. It has been argued that faster development in open nesting birds has evolved in response to greater risk of predation. Recent work in chickens has shown that vitamin D enhances skeletal growth, immune function, and gut development in chicks maintained in dark conditions and low vitamin D inhibits brain development in mouse pups. Thus, I reasoned that differences in the rates of development between cavity nesting and open nesting birds might be explained by differences in available sunlight, its effects on vitamin D synthesis, and the effect of vitamin D on development. I addressed this question by comparing the skeletal size and mineral content and organ size between Eastern Bluebird chicks supplemented with vitamin D3 (cholecalciferol) or water (control) on days 4-13 post-hatching. Treatment groups were compared on day 14. There was no effect of treatment on body mass, body size, bone mineral content, size of the immune organs, length of the intestine, or mass of the brain. Assuming that vitamin D is important for development in bluebirds, it is likely that mothers are depositing sufficient vitamin D in their egg yolk to support pre-fledging development.