General characteristics of the intensity of elimination in the early ontogenesis of colonial bird species

This paper examines the rate of elimination in the early ontogeny of colonial bird species. The research objects were colonial nesting species – black-necked gull (Larus ridibundus L.) and black-necked grebe (Podiceps nigricollis C.L. Brehm), which form monospecific and poly-species colonial settlements. The rate of elimination was determined taking into account the stage of completion of the clutch, as well as the position of the nest in the structure of the colonial settlement: in the biological center or at the periphery of the colony. The nesting life of colonially nesting species was studied according to the generally accepted method, taking into account the choice of a place for building a nest by birds, the morphology of the nest, the intensity of oviposition and other characteristics. In the course of many years of research 3 types of nest placement within the colony have been identified. The maximum elimination rate has been proven for fixing the nest on the floodplain of common reed. The minimum rate of elimination was found for black-headed gull nests built on the fold of common reed (Phragmites australis) and narrow-leaved cattail (Typha angustifolia). Near-nesting vegetation is located around the nests of black-necked gull and black-necked grebe. The variant of placing vegetation around the nest prevails. Less common are options in which vegetation is located on one side. Observations have not revealed a relationship between the rate of elimination and the nature of the distribution of vegetation around the nest. The authors have compared the rate of elimination of black-headed gull nests located in the biological center and at the periphery of the colony. Elimination is possible both during the laying of the first egg and after the end of the clutch. Observations have shown that the rate of elimination is higher for nests from the periphery of the colony, which may be associated with differences in the size of the nests, the rate of their construction, as well as with the behavior of birds incubating eggs. The maximum rate of elimination of nests and eggs at the periphery of the colony is also manifested in the early ontogenesis of the black-necked grebe. The intensity of elimination and the forms of its manifestation affect the structure of the colonial settlement of birds and characterize the level of individual and group adaptation of birds to the conditions in which the nesting period takes place.