Food of young and colony-attendance of adult guillemotsUria aalge on Helgoland

The guillemot colony on Helgoland, Germany, was visited from June 5th to 21st 1990. The presence of adults and food delivery to chicks was studied on a ledge holding about 50 breeding pairs. Attendance varied through the day, with most birds present at mid-day. Food consisted only of fish, 94.6% Clupeidae (herring and sprat) and 5.4% sand-eel. On average, a chick received 2.72 fish per day. After a marked early morning peak of feeding, the number of feeds per hour levelled off to a constant rate during the rest of the day until dusk. At sea, high numbers of guillemots were present in front of the colony, with densities dropping steeply with distance. The birds are thought to forage at distances of more than 5 km away from the colony.