Do Adult Little Egrets Respond to Disturbance at Their Nest by Increased Breeding Dispersal?

When studying breeding dispersal with marked individuals, manipulation-induced disturbance should not affect movement patterns. As part of a study on the Little Egret (Egretta garzetta), we tested whether the capture of breeding adults at their nest and handling (i.e., disturbance) increased their probability to move to a new colony in the subsequent breeding season (i.e., breeding dispersal). The proportion of adults disturbed in a given year that had changed colony in the subsequent breeding season was compared with the dispersal of adults observed during at least two consecutive years at colonies and not disturbed on the previous year: (1) birds marked as chicks and (2) birds marked as adults and observed ≥ two years after capture at the nest. Disturbed birds were not found to have an increased propensity to disperse. We conclude that, for this species, capture did not increase the subsequent breeding dispersal.