The spatial structure of the brent (Branta bernicla) and red-breasted (Branta ruficollis) geese (Anseriformes, Anatidae) breeding settlements on Taimyr Peninsula: Single-species colonies and associations with large gulls

The studies were carried out in 2000–2007, 2010 and 2012–2014 along the Agapa River from the upper reaches downstream to the mouth, the western part of the central Taimyr Peninsula, and in the vicinities of the Medusa Bay, in the northwestern part of the Taimyr Peninsula. On the off-shore islands, brent geese nest in pairs or in small groups that join the colonies of the Taimyr herring gull ( Larus argentatus taimyrensis ). In addition, these geese form their own colonies of several dozens of nests. These colonies are not related to gull colonies even if the latter exist on the same island. Mixed multi-species colonies with the brent goose prevalence are less dense than those where gulls prevail. The gulls that breed near the colonies, where brent geese prevail, place their nests at such distances from the nearest geese nests that are approximately identical to the distances between the nests of brent geese. In the colonies with the prevalence of gulls, brent geese also nest with approximately the same density as gulls, fitting into the colony as a spatially equal element. In the red-breasted geese, in contrast to brent geese, the nesting density does not correspond to that of the gulls. Red-breasted geese behave either as a foreign element within a gull colony and establish their own nests very close to gull nests up to evicting gulls from their places or as outside strangers that breed at some distance from gull colonies.