Monday, August 7, 8:00-11:30 am
COS 13 - Avian ecology
Heritage Ballroom I, Marriott
Presiders: J Martin and B Reynolds

Analysis of Breeding Bird Survey data provides evidence for long-distance dispersal in many songbird species.

Tittler, Rebecca*,1, Fahrig, Lenore1, Villard, Marc-André2, 1 Geomatics and Landscape Research Ecology Laboratory, Ottawa, ON, Canada2 Canada Research Chair in Landscape Conservation, Moncton, NB, Canada

ABSTRACT- Dispersal has ling been considered a key process in population dynamics. Knowledge of dispersal distances should help determine the scale over which management of one habitat patch may affect populations in other patches. However, it has often been difficult or even impossible to study the dispersal distances of relatively small organisms that travel long distances, such as songbirds. Using the North American Breeding Bird Survey database, we examined time-lagged patterns of abundance between populations of North American songbirds at various distances apart, from 10 to 100 km. We argue that populations that show consistent one-year time-lagged correlations in abundance are linked by dispersal, and that therefore the distances separating such populations correspond to dispersal distances. We found such one-year time-lagged correlations for 25 of the 51 species examined. There was a significant effect of sample size on the probability of finding such an effect (i.e., the species for which we found an effect were those for which we had larger sample sizes). The dispersal distances indicated for these 25 species ranged from 10 to 100 km, an order of magnitude greater than those previously reported in the literature for many species. Wingspan was a significant predictor of dispersal distance for these 25 species. These results indicate that many North American songbird species disperse over greater distances than previously thought, and that those with larger wingspans disperse farther. Management and conservation decisions should therefore be made at appropriately large spatial scales.

Key words: north american songbirds, time-lagged dispersal model, bbs data

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