Nest-site selection by Marsh Harrier (Circus aeruginosus) in the shore belt of Helophytes on large lakes

Nest-site selection by Marsh Harrier (Circus aeruginosus) was investigated on Lakes Meteliaiand Obelija in 1983n1986 and Lake fialtytis in 1984n1986 in southern Lithuania. Fifty five breedingpairs were detected and 49 nests (89.1%) were found. With regard to the potential breeding habitat,Lakes Meteliai and fialtytis represented extreme structural types, whereas Lake Obelija n the intermediatetype. Despite these differences, most nest-site parameters of the three lakes did not differ ordiffered slightly. The most similar was the depth. Only the most dissimilar lakes differed according tonest-site vegetation density and height, the latter varied according to the dominant helophytic specieson the lake. Distances from nests to water and shore were not statistically significant n nests were builtin the middle of the emergent vegetation belt. While selecting nest-sites, pairs gave preference topatches larger in area and diameter. Nest-site selection peculiarities are explained by birdsi balancedefforts to protect clutches from terrestrial mammalian predation and the destructive impact of hydrodynamicprocesses.

Vitas Stanevicius, Acta Zoologica Lituanica, 2004, Volumen 14, Numerus 3