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KLEPTOPARASITISM OF SANDWICH TERNS STERNA SANDVICENSIS BY BLACK‐HEADED GULLS LARUS RIDIBUNDUS
Author(s) -
Fuchs Eduard
Publication year - 1977
Publication title -
ibis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.933
H-Index - 80
eISSN - 1474-919X
pISSN - 0019-1019
DOI - 10.1111/j.1474-919x.1977.tb03535.x
Subject(s) - fledge , sterna , kleptoparasitism , biology , larus , fishery , tern , fish <actinopterygii> , ecology , zoology , predation , herring
SUMMARY The parasitic behaviour of Black‐headed Gulls in a mixed colony of terns and gulls at the Sands of Forvie on the northeast coast of Scotland is described in some detail. Food‐stealing occurred with varying frequency throughout the breeding season. Less than 6% of the terns were attacked during incubation and when their chicks were a few days old, but up to 29% were attacked thereafter. At the same time the percentage of successful attacks rose from 1% or less to 6.5%. Food items brought back to the ternery were predominantly sandeels, clupeids and gadoids. Only a small proportion of terns carrying fish shorter than 7 cm were attacked whether they were sandeels, clupeids or gadoids. Robbing success was higher with clupeids and gadoids than with sandeels. The effect of the Black‐headed Gulls' kleptoparasitism on the Sandwich Terns' breeding success is thought to have been negligible during incubation and early chick‐life, but might have influenced fledging weight and ultimately post‐fledging survival.