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.

Duration of colonial bird species egg incubation

The paper deals with one of the aspects of bird early ontogenesis biology - egg incubation duration, which was defined as the time interval between egg laying and hatching from it. The oomorphological parameters are determined taking into account the ordinal number of the laid eggs. Parameters of early ontogeny of birds are studied on the example of colonially nesting species: blackberry toadstool ( Podiceps nigricollis C.L. Brehm.) and lake gull ( Larus ridibundus L.). Within the colonial settlement of these species, the biological center and the periphery of the colony were isolated. When studying the parameters of early ontogeny of birds and oomorphological characteristics, the same number of eggs was taken into account. During field and laboratory studies it was found that the incubation of eggs lasts longer in eggs from the nests of the biological center of the colony. The first eggs are incubated longer. These features clearly manifested in the early ontogeny of the gull. The increase in the egg incubation duration occurs against the background of an increase in their mass and a decrease in the concentration of lysozyme in the protein shell of the egg. Egg incubation duration is one of the results of embryonalization as a way of evolution of ontogeny. The manifestation of the results of embryogenesis was revealed for the first eggs in the nests of the biological center of the colony. Embryonalization leads to an increase in egg incubation duration as well as to a decrease in the intensity of elimination in early ontogenesis, which affects the number of individuals breeding in the colony and, accordingly, the structure of the colonial settlement of birds.

ФЛОРА ТА РОСЛИННІСТЬ ОСТРОВА МАРТИНЯЧОГО (АЗОВО-СИВАСЬКИЙ НАЦІОНАЛЬНИЙ ПРИРОДНИЙ ПАРК, ХЕРСОНСЬКА ОБЛАСТЬ, УКРАЇНА)

<p>The goal of research is to evaluate the current state of phytodiversity of Martyniachyi Island in order to predict its change under the bird influence. The botanical research was carried out by traditional methods. Species and Families are presented according to Vascular plants of Ukraine Checklist (Mosyakin, Fedoronchuk, 1999). The article presents the latest data on phytodiversity of Martyniachyi Island located in the Sivash Gulf of Azov Sea. Contemporary taxonomy (31 species of vascular plants) and syntaxonomy diversity (11 associations from 7 formations) of the island is established. The flora of the island consists mainly of annual plant species (80.6 %). This testifies to the ephemerality of “nature” communities of the island, which develop under the influence of colonial bird activity. Species diversity of communities is low, that is because of island isolation and small area, and also because of significant bird influence. Among the plant communities the formation <em>Si</em><em>symbrieta</em><em> </em><em>loeselii</em> is dominate. Communities of formations <em>Anisant</em><em>h</em><em>eta</em><em> </em><em>sterilis</em><em>, </em><em>Asperugeta procumbens, Atriplexideta</em><em> </em><em>tataricae</em><em>, </em><em>Atriplexideta</em><em> </em><em>aucherii</em><em>,</em><em> Hyoscyameta nigrii,</em> <em>Suaedeta</em><em> </em><em>confusae</em> occupy comparatively less island area. Synthaxonomy of the island vegetation based on the ecological and floristic classification includes plant communities from 2 classes, 2 alliances, 3 units, and 6 associations.</p><p>The principal factor influenced the quantitative diversity of island vegetation and its spatial structure is the influence of colonial bird settlement, namely <em>Laridae</em>.</p>

Intra population polymorphism of Caspian gull (Larus cachinnans) from the North-Western Coast of the Azov Sea (oological aspect)

This study presents the results of a long term study of nesting colonies of the Caspian gull (Larus cachinnans Pallas, 1811) on the islands of the Molochniy Liman and in Obitochnaya Bay (Azov Sea), in the South of Ukraine (Zaporizhia region), conducted between 1988 and 2013. A description of the size and coloring of eggs of Caspian gull was conducted by generally accepted methods. We measured 1000 eggs from 5 colonies of Caspian gulls. The background coloration of the eggs’ shells was classified into 7 types, the pattern of markings on the surface of the shells was classified into 4 types. In the nesting colonies, comprising different nesting settlements, the study tested differences in the distribution of typical and atypical coloring types and patterns on the surface of the shells. The background color and character of the shell marking patterns is dominated by eggs of phenotypes 3 and 4: gray-green, with a pattern of spots, of medium size (5–60%) and brown, with a pattern of large spots (2–40%). In different settlements the Caspian gull egg sizes vary in length and diameter of 54.5–86.3 x 39.2–60.4 mm, volume 61.7–113.7 cm3 and index of roundness 63.6–85.3%. The study revealed that the linear dimensions of eggs also depend on the number of birds in the nesting colonies. We found that morphological and dimensional characteristics of Caspian gull eggs can vary at certain intervals and characterize individual colonies, settlements and populations. Based on cluster analysis, conducted in terms of the average of the linear sizes of eggs of Caspian gull from several populations within the range of the species, the study identified three groups of colonies – Danube-Sivash, Azov-Black Sea and Caucasus-Caspian. In region of the Azov-Black Sea, the greatest similarity was shown between the settlements of Sivash and the South of Crimea, which in turn is similar to Lebiyazhyi Islands and Kaniv Nature Reserve (river Dnipro). A related link combined the Azov and Black Sea branches, while the Caucasus-Caspian group is relatively separate. As a result this study the influence of the number of nesting birds on the dimensional characteristics of the eggs was established; in the period of increase in the Caspian gull population from the 1970s to the early 1990s they had the highest scores, and in periods of decreasing population in 2001–2005, their values were lowest. Consequently, the use of oomorphological indicators turned out to be a fairly easy and objective method for studying the monitoring data for separate colonial bird species.

Ectoparasitism shortens the breeding season in a colonial bird

When blood-feeding parasites increase seasonally, their deleterious effects may prevent some host species, especially those living in large groups where parasites are numerous, from reproducing later in the summer. Yet the role of parasites in regulating the length of a host's breeding season—and thus the host's opportunity for multiple brooding—has not been systematically investigated. The highly colonial cliff swallow ( Petrochelidon pyrrhonota ), a temperate-latitude migratory songbird in the western Great Plains, USA, typically has a relatively short (eight to nine week) breeding season, with birds rarely nesting late in the summer. Colonies at which ectoparasitic swallow bugs ( Oeciacus vicarius ) were experimentally removed by fumigation were over 45 times more likely to have birds undertake a second round of nesting than were colonies exposed to parasites. Late nesting approximately doubled the length of the breeding season, with some birds raising two broods. Over a 27 year period the percentage of birds engaging in late nesting each year increased at a colony site where parasites were removed annually. This trend could not be explained by changes in group size, climate or nesting phenology during the study. The results suggest that ectoparasitism shortens the cliff swallow's breeding season and probably prevents many individuals from multiple brooding. When this constraint is removed, selection may rapidly favour late nesting.