Dispersal in Tree Swallows, experiments and prospects.

WINKLER, DAVID W.; WREGE, PETER H.; LLAMBÍAS PAULO E; FERRETTI VALENTINA; HOSNER, PETER; SULLIVAN, PATRICK J.

Congreso; 121st Stated Meeting of the American Ornithologists Union; 2003

Since 1985, we have been accumulating information on the natal and breeding sites of Tree Swallows in the vicinity of Ithaca, NY, and increasingly, around the whole of New York. Inanalyses of almost 800 natal dispersal events, the distribution of distances dispersed issubstantially compressed relative to the distribution of potential recapture distances, and tests ofdifferent null hypotheses for dispersal distance distributions yield insights into the processes underlying dispersal. Recently completed large-scale brood-manipulation experiments further explore the biological basis of dispersal distance decisions, testing the hypothesis that birdsraised in more crowded nests disperse farther than those from less crowded nests. These studieson natal dispersal have re-kindled our interest in dispersal movements among already breedingbirds, and a series of nest-closure experiments yield insights into which adults move and why.Observations on males associated with >1 box/season indicate some surprising flexibility in thespatial ecology of these birds. These data taken together reinforce the distinction between natal and breeding avian dispersal, but they also suggest interesting contrasts in the ways thatinformation is gathered and processed in birds of different ages and breeding stages.