LOCAL SURVIVAL, NATAL DISPERSAL, AND RECRUITMENT IN LITTLE EGRETS EGRETTA-GARZETTA

Survival rates, natal dispersal, and age at first breeding of Little E grets Egretta garzetta breeding in the Camargue (southern France) were estimated using individually marked birds observed in nesting colonie s from 1987 to 1995. Survival and probability of resighting were estim ated separately, using capture-mark-recapture models. Annual survival rates of adult breeding birds were constant (71.4%) during the study p eriod, whereas the survival rates of yearlings showed marked variation s between years, ranging from 6.54% to 55.19%. Rank in the brood at fl edging had no effect on subsequent first-year or adult survival. There was no evidence for an effect of winter severity or trophic condition s at fledging on first-year survival during the study period. Age and time (study year), but not rank in the brood, had a significant intera ctive effect on resighting rates. A higher proportion of philopatric i ndividuals was observed among birds first observed breeding at age one , compared to individuals observed breeding for the first time at an o lder age. Little Egrets that settled in colonies other than the natal one, dispersed at fairly even distances, with only a slight tendency t o stay close to their natal colony. There was no influence of rank in the brood on the degree of philopatry. Direct observations and estimat es from demographic models revealed that a substantial proportion of b irds started breeding at age one, with large variations between years. This pattern of recruitment contrasts markedly with previous records for Ciconiiforms.