Physical Sciences and Mathematics Commons^™

Heritable Choice Of Colony Size In Cliff Swallows: Does Experience Trump Genetics In Older Birds?, Erin A. Roche, Charles R. Brown, Mary Bomberger Brown

School of Natural Resources: Faculty Publications

The variation in breeding colony size seen in populations of most colonial birds may reflect heritable choices made by individuals that are phenotypically specialized for particular social environments. Although a few studies have reported evidence for genetically based choice of group sizes in birds, we know relatively little about the extent to which animals potentially rely on experience versus innate preferences in deciding how many conspecifics to settle with at different times of their lives. We conducted a cross-fostering experiment in 1997–1998 on cliff swallows, Petrochelidon pyrrhonota, in southwestern Nebraska, USA, in which some individuals were reared in colonies …

Natural Selection And Age-Related Variation In Morphology Of A Colonial Bird, Mary Bomberger Brown

School of Natural Resources: Dissertations, Theses, and Student Research

In May 1996, inclement weather led to the deaths of thousands of Cliff Swallows (Petrochelidon pyrrhonota) in Nebraska. Survivors had larger skeletons, shorter wings and tails, and less wing asymmetry than non-survivors. This population was followed for 10 years to study 1) whether natural selection events result in permanent microevolutionary changes, 2) if variation in climate affects the development of morphological traits, and 3) if morphological traits vary systematically with age.

Patterns in morphology exhibited by swallows following the selection event were studied by measuring yearling birds. Wing and middle tail lengths decreased, beak length and width increased, …