ABSTRACT: Kittiwakes from the colony closest to the site of the wreck of the 'Braer' oil tanker in Shetland, Scotland, in 1993 were studied in the breeding season following the spill. Sub-lethal effects of the spill on breeding kittiwakes were assessed by comparison with an extensive data set collected at the same site (Sumburgh Head) during the 3 yr prior to the spill. Breeding performance in 1993 was very similar to that in 1992, with relatively good breeding success and short, frequent foraging trips. However, haematological data revealed a significant level of anaemia in the breeding kittiwakes at Sumburgh in 1993 compared to birds sampled in the same year at control colonies elsewhere in Scotland. The return rate of adults to the Sumburgh colony between 1992 and 1993 was exceptionally low, and nest-site and mate fidelity also appeared low. This was not a consequence of reduced survival, but was due to some adults not breeding in 1 or 2 yr following the spill, and subsequently returning to breed at the colony in later years. Such behavioural disruption may have considerable consequences for the dynamics and structure of the colony.

KEY WORDS: Oil pollution · Seabird · Anaemia · Breeding performance · Colony attendance · Annual survival · Non-breeding

Published in MEPS Vol. 155 (1997) on August 28
ISSN: 0171-8630. Copyright © Inter-Research, Oldendorf/Luhe, 1997