The nesting parameters of the Black-headed Gull in various habitat types within a colony. - B. Pakula. - Berkut. 14 (2). 2005. - P. 193-200.
Studies on the breeding ecology of the Black-headed Gull were conducted from 1999–2001 in a nest colony with about 6000 pairs. Three different habitats were distinguished based on the type and height of plants: nettles, grasses and sedges. The highest density of nests was found in the areas of sedge growth, 0.56 ± 0.01 nest/m2, while the lowest density, 0.29 ± 0.17 nest/m2, was in the areas dominated by nettles. The differences in nest density were reflected in the significantly different mean distances between nests. The smallest distance recorded in the area of sedge growth was 1.2 ± 0.4 m., with the greatest distance in the area of nettle growth 1.6 ± 0.7 m. Strong synchronisation to the start of nesting was observed in all the analysed habitats. Habitat type was not found to influence clutch size, number of nests with hatching success, number of hatched eggs and mean number of hatchlings per pair. Complete nest losses occurred from 16 % in sedge areas to 23 % in grass and nettle areas. The most serious cause of nest loss was predation, which increased in the second half of the breeding season. Significantly more broods were lost to predation in grassy areas. An analysis of nesting parameters shows that habitat type influences competition for the location of nest territories, density of nesting pairs and predator pressure, but it does not, however, influence clutch size or hatching success. [English].
Key words: Black-headed Gull, Larus ridibundus, Poland, breeding ecology, habitat selection, nest.
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