PARENT-OFFSPRING CONFLICT OVER INDEPENDENCE IN THE HERRING GULL (LARUS-ARGENTATUS)

Observations on 24 focal nests revealed that, at the time when parental investment in feeding fledging chicks declined, chicks showed a marked increase in begging, particularly in larger broods, whilst parents became less responsive to begging. That chicks suffer a cost from early termination of investment is indicated by the fact that third-hatched chicks, who had attempted (unsuccessfully) to initiate more feeds, were absent from the territory first, rather than the more mature first- and second-hatched chicks. Taken together, these results and related inter- and intra-brood contrasts in behaviour are interpreted as offering support for TRIVERS' theory of parent-offspring conflict over the termination of investment.