Ardea
Official journal of the Netherlands Ornithologists' Union

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Kristiansen J.N. & Jarrett N.S. (2002) Inter-specific competition between Greenland White-fronted Geese Anser albifrons flavirostris and Canada Geese Branta canadensis interior moulting in West Greenland: Mechanisms and consequences. ARDEA 90 (1): 1-13
In recent years, breeding Canada Geese Branta canadensis interior have established themselves in areas of West Greenland previously exploited by Greenland White-fronted Geese Anser albifrons flavirostris only. In this study, diet, behaviour and spatial distribution of moulting non-breeding Greenland White-fronted and Canada Geese were studied in sympatry and in allopatry, in order to assess the degree of potential inter-specific competition. In a sympatric site, the diet of Greenland White-fronted Geese comprised significantly higher content of low quality mosses compared to sympatric Canada Geese and both species in allopatry. Sympatric Greenland White-fronted Geese also showed a significantly broader diet (niche breadth) and lower intake rate than Canada Geese in sympatry and both species in allopatry. Sympatric Greenland White-fronted Geese spent significantly more time feeding possibly to compensate for the low quality food and the low intake rate. Several physical inter-specific agonistic interactions were recorded with Greenland White-fronted Geese being the loser in all cases. In the study area, numbers of Canada Geese increased from c. 1090 birds coincident with a decrease of Greenland White-fronted Geese from c. up to 70 to 5 birds during 1988-1998. These results suggest that inter-specific competition between Greenland White-fronted Geese and Canada Geese has occurred and may still occur in West Greenland


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