Post-Fledging Parental Care in the Western Gull

Post-fledging parental care of Western Gulls (Larus occidentalis) was examined by following in-colony and post-dispersing movements of marked adults and young. At a large offshore colony, parental care ceased when young dispersed at a mean age of 70 days, but at some mainland and nearshore Western Gull colonies parental care may last longer. At the latter sites competition for food appeared low, foraging territories and food items could be defended by adults, and food sources were near nest sites. A low incidence of prolonged parental care in this species may result from activities of a few well-adapted individuals who specialize in foraging techniques facilitating extended breeding efforts.