Ecotoxicological and pathological studies of common guillemots Uria aalge beached on the Belgian coast during six successive wintering periods (1989-90 to 1994-95)

During 6 successive wintering periods, 727 common guillemots Uria aalge were recovered from Belgian beaches. One-third of the birds were already dead; the rest passed through rehabilitation centres where they eventually died. All birds were monitored for general condition (body mass, fat reserves), eventual status of oiling and pathological changes (cachexia, acute hemorrhagic gastroenteropathy); 339 birds were sampled for trace metals (total and organic Hg, Cu, Zn, Fe, Cd) and PCB (polychlorinated biphenyl) analysis. Oiling is still a major cause of death for wintering pelagic seabirds: half of the birds showed signs of external or internal oiling, probably a still greater number of oiled birds never reach the shores. Although a low body mass can be considered a normal winter condition for wintering guillemots, pathology results showed that three-quarters of the studied animals were in a state of cachexia with emaciated pectoral muscle and lowered muscle lipid content. Elevated levels of Cu, Zn, Hg and PCBs were linked to the state of cachexia and may well represent an additional stress factor leading to the debilitation and death of part of the wintering guillemot population

Habitat foraging niche of a High Arctic zooplanktivorous seabird in a changing environment

Abstract Here, we model current and future distribution of a foraging Arctic endemic species, the little auk (Alle alle), a small zooplanktivorous Arctic seabird. We characterized environmental conditions [sea depth, sea surface temperature (SST), marginal sea ice zone (MIZ)] at foraging positions of GPS-tracked individuals from three breeding colonies in Svalbard: one located at the southern rim of the Arctic zone (hereafter ‘boreo-Arctic’) and two in the high-Arctic zone on Spitsbergen (‘high-Arctic’). The birds from one ‘high-Arctic’ colony, influenced by cold Arctic water, foraged in the shallow shelf zone near the colony. The birds from remaining colonies foraged in a wider range of depths, in a higher SST zone (‘boreo-Arctic’) or in the productive but distant MIZ (second ‘high-Arctic’ colony). Given this flexible foraging behaviour, little auks may be temporarily resilient to moderate climate changes. However, our fuzzy logic models of future distribution under scenarios of 1 °C and 2 °C SST increase predict losses of suitable foraging habitat for the majority of little auk colonies studied. Over longer time scales negative consequences of global warming are inevitable. The actual response of little auks to future environmental conditions will depend on the range of their plasticity and pace of ecosystem changes