How far do songbirds disperse?

Abstract

Dispersal distances determine the scales over which many population processes occur. Knowledge of these distances may therefore be crucial in determining the appropriate spatial scales for research and management. However, dispersal distances are difficult to measure, especially for vagile organisms like songbirds. For these species, the use of traditional mark–recapture and radio‐telemetry methods is problematic. We used positive one‐year time‐lagged correlations in abundance to estimate natal dispersal distances. Using the North American Breeding Bird Survey database, we examined one‐year time‐lagged correlations between pairs of North American songbird samples separated by 10–100 km. We submit that consistent positive one‐year time‐lagged correlations reflect the exchange of individuals through dispersal. We found positive one‐year time‐lagged correlations between pairs of samples from 25 different songbird species. The median distances of these correlations ranged from 15 to 95 km, depending on the species. These distances were positively correlated with body size and wing length. Dispersal appears to be the most parsimonious explanation for the time‐lagged correlations we observed in these species. The putative dispersal distances we measured are generally an order of magnitude longer than those reported in the literature.