KLEEFTRA R & BLES A (2000) Greylag Geese Anser anser nesting in trees: a new trend?. LIMOSA 73 (4): 148-150.

During breeding bird surveys in two peat bog areas in the province of Friesland in 2000, two pairs of Greylag Geese were found nesting in birch trees. Both nests were built at an altitude of about 9 m, in nests formerly used by Buzzard and Goshawk. The nests were still occupied by their original owners at the start of the breeding season, but were apparently occupied by the greylags later on. The first nest, at Easterskar (near Sintjohannesga), contained 6 eggs on 31 March. However, it seemed already abandoned as there were no signs of the geese and the eggs were not incubated. In the second area, De Deelen (near Aldeboarn), was found in the second half of April. A check on 1 May revealed 5 eggs. Like in Easterskar, this nest was not occupied anymore. Moreover, no alarming geese were found in close vicinity. Tracks indicated disturbance by a marten (probably Stone Marten). Later on, the nest was re-occupied by a pair of Egyptian Geese. Contrary to the nesting-behaviour of this species, tree-nesting Greylag Geese are a novelty in The Netherlands. Increasing predat ion pressure by Foxes, marten and other ground-dwelling predators, might stimulate Greylag Geese to abandon their ground-nesting behaviour in favour of nests in trees, a trend which has already been reported for species like Purple Heron.Greylag Goose Anser anser

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