THE INFLUENCE OF AGE ON THE ACQUIREMENT OF A PERCH IN THE BLACK-HEADED GULL (LARUS-RIDIBUNDUS L) - NEW DATA AND A REVIEW OF THE LITERATURE

In captive black-headed gulls (Larus ridibundus L.), immature birds of ten win encounters with adults. Under natural conditions, immatures wi n more fights as challenger, but lose more as challengee if no food is involved. Immatures win more fights for food, both as challenger and as challengee. From the results presented here, and after reviewing th e literature on aggressive interactions in the black-headed gull, it i s concluded that immatures start and win more fights than adults. They are also more daring in interactions with other species. Some of thes e differences are probably a result of different foraging strategies o f immatures and adults. However, fighting itself may have a higher val ue for immatures than for adults, perhaps as part of a learning strate gy.