Meeting Abstract

P3.161  Monday, Jan. 6 15:30  Growing up in the dark isn’t so bad, part II: Development of cavity nesting bluebirds is not limited by access to UVB light POUNDSTONE, M.M.*; HOOD, W.R.; Auburn University ; Auburn University mmp0015@auburn.edu

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 a 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, we 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. A prior study suggested oral supplementation with vitamin D had no impact on offspring development. Yet, vitamins are inherently labile and thus, it is possible that the lack of effect was due to low vitamin D activity rather than an inability of the birds to respond to the treatment. As a follow up, we asked if natural production of vitamin D through exposure to UVB light would impact development. We compared the skeletal size, mineral content, and organ size between Eastern Bluebird chicks exposed to UVB light for 1h per day between days 2-13 post-hatching. Treatment groups were compared on day 14. We found no effect of treatment on body mass, body size, bone mineral content, length of the intestine, and size of any of the major visceral organs. These findings provide further evidence that access to sunlight during postnatal growth in bluebirds does not limit growth. 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.