SURVIVAL OF SPOONBILLS ON WADDEN SEA ISLANDS

The Spoonbill populations in Europe are fragmented and threatened. The dynamics of the species is poorly known but ringing and observation p rogrammes are under way. Here we estimated the local survival of two c olour-ringed populations of Spoonbills in the Netherlands. Adult survi val and sighting rates, estimated with the Cormack-Jolly-Seber model, were high and constant over a 10-year period (1986-1996) and no differ ences could be detected between the two populations. Juvenile survival , estimated from the observed return rate, did not vary over a 5-year period (cohorts 1986-1990). However, at least in one of the two popula tions, the proportion of birds returning by two years of age increased over a 9-year period (cohorts 1986-1994). Thus there is only weak sup port for the idea that the recent increase in population size was driv en by an increase in local survival. Our work on survival provide a fi rst step towards a larger appreciation of the population dynamics and life-history of the Spoonbill.