Inter-specific competition can occur where two or more species overlap in diet and/or spatial distribution.
Such interactions might be most prevalent where a species invades areas previously occupied by another species. In West Greenland, the number of native Greenland White-fronted Geese has decreased over the last 15-20 years, while the Canada Goose, a species new to the area, has increased. This study explores the overlap in diet and space use of these species in Mudderbugten and Kvandalen, together with factors that could influence the degree of competition between the two species. Data on activity budgets and spatial distribution were obtained from observations of behaviour, and diet selection was determined through analyses of plant epidermal fragments in faecal samples that were subsequently genotyped to goose species. No differences in diet or spatial distribution of the two species were found, and behavioural observations indicated only slight modifications in attentive behaviour and increased distance to the lakeshore in sympatry. This would seem to imply that the area has sufficient space and forage to support both species. If so, the local decline
in Greenland White-fronted Goose may reflect population fluctuations for reasons other than the increased presence of the Canada Goose.