Vitas Stanevičius

THE STATUS, NUMBERS AND DISTRIBUTION OF SWANS AND GEESE IN LITHUANIA

Abstract The status, numbers, distribution, populations trends and habitat use of swans and geese in Lithuania are analysed. 3 species of swans and 10 species of geese are recorded in Lithuania. Only the Mute Swan Cygnus olor, Whooper Swan Cygnus cygnus and Greylag Goose Anser anser breed, while all other species occur as passage migrants, winterers or vagrants. With few exceptions, the status of swan and goose populations in Lithuania is favourable. Most populations are stable or increasing. The only species which has markedly decreased in numbers during the last decades is the Bean Goose Anser fabalis. There is special concern about the status of the globally threatened population of the Lesser White-fronted Goose. In recent years several Lithuanian staging grounds has been holding up to 5% of the total Lesser White-fronted Goose NE Europe population, but so far this species in Lithuania is not protected and it is still in the list of huntable species. Conflict of migratory wildfowl with agriculture is ...

Trends in the Composition of Breeding Bird Communities: Anthropogenic or Climate Change Induced Process?

The article supports the hypothesis that the balance between anthropogenic and climate change-induced impacts on bird communities in the Baltic States has recently shifted towards a more pronounced climate impact. The results suggest that a climate warming-induced change in the composition of bird communities is not a universal process: it is a spatial and species-specific process. The article demonstrates that the impact of climate change on moist habitat birds is more dramatic than that on wetland, water and terrestrial birds. Birds of moist habitats predominate among the species with decreasing Lithuanian populations on the southern periphery of the species range. A list of affected bird species is presented and a new conception for more effective bird protection is introduced.

Nonbreeding Avifauna and Water Ecosystem Succession in the Lakes of Different Biological Productivity in South Lithuania

Changes in nonbreeding waterfowl fauna on seven lakes of South Lithuania (Dusia, Metelys, Obelija, Simnas, Žaltytis, Žuvintas, Amalvas), which are in various stages of succession, were evaluated as a component of that succession in 1991-1997 and investigated in the level of populations and multispecies assemblages of nonbreeding water birds. The analysis of the structure of assemblages trends and population indices in the gradient of productivity of lakes was carried out. A simulated model of succession allowed us to determine increasing rate and prevalent direction of negative changes in bird assemblages and species populations and vulnerability to succession of avifauna of different water ecosystems. These changes were mostly determined by mass species in separate parts of the gradient: herbivorous (negative in eutrophic and neutral in mesotrophic) and zoovorous (positive in mesotrophic and negative in eutrophic). Since the 1990s, this regularity has undergone some modifications. Due to the analyses of ...

Coexistence and population genetic structure of the whooper swan Cygnus cygnus and mute swan Cygnus olor in Lithuania and Latvia

Two closely related swan species, the mute swan Cygnus olor and the whooper swan Cygnus cygnus, were formerly allopatric throughout their breeding ranges, but during the last decades a sympatric distribution has become characteristic of these species in the Baltic Sea region. The whooper swan has gradually replaced the mute swan in many suitable habitats in Lithuania and Latvia. Marked differences in the genetic population structure of both species may partially explain the dominance of the whooper swan, as genetic population divergence can be a major factor affecting inter-specific competition. A homogenous genetic population structure was defined for mute swans breeding in Lithuania, Latvia, Poland and Belarus. Breeding mute swans in this region are mostly of naturalised origin. A diverse population genetic structure characterizes whooper swans breeding in Lithuania and Latvia.

Nest-Site Selection by Coot and Great-Crested Grebe in Relation to Structure of Halophytes

Parameters of potential, optimal and sub-optimal habitats of Coot and Great-crested Grebe were established based on measurements of nest-site characteristics. Nest-site selection is determined by an intricate interaction of vegetation density, water depth, distance to the open water, diameter of a shore-belt of halophytes, as well as ecomorphological peculiarities of a species. A conclusion is made that major criteria are nest resistance to the impact of waves, possibility to reach a nest by water unobstructed, and a breeding birds safety. The impact of structural peculiarities of a zone of halophytes to the above parameters of a nest-site on lakes of different succession stages was estimated.

PRODUCTIVITY OF STAGING GROUNDS FOR WATERFOWL IN LITHUANIA

Abstract The productivity of staging grounds for waterfowl and the reasons for the productivity were investigated using th. 1996–1997 country-wide survey data. 29 waterfowl staging grounds were grouped into 8 ecological types basing on trophical level, origin and distance from the Baltic Sea coast. The productivity of waterfowl staging grounds was proved to be due to a complex of different factors, ecological (water depth, submerged plants, bottom invertebrates, etc.) and geographical (distance from the Baltic sea coast) ones being the main. Ecological factors dominate over geographical ones, though the significance of the former depends upon species-specific diet and feeding habits, while the geographical factor is important to nearly all the species. Differently from other waterfowl species, for the geese feeding on the land it is the productivity of feeding habitats neighbouring wetlands and the size of seasonally flooded areas that are of the highest significance. Currently existing waterfowl staging ...

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 Meteliai and Obelija in 1983–1986 and Lake Žaltytis in 1984–1986 in southern Lithuania. Fifty five breeding pairs were detected and 49 nests (89.1%) were found. With regard to the potential breeding habitat, Lakes Meteliai and Žaltytis represented extreme structural types, whereas Lake Obelija – the intermediate type. Despite these differences, most nest-site parameters of the three lakes did not differ or differed slightly. The most similar was the depth. Only the most dissimilar lakes differed according to nest-site vegetation density and height, the latter varied according to the dominant helophytic species on the lake. Distances from nests to water and shore were not statistically significant – nests were built in the middle of the emergent vegetation belt. While selecting nest-sites, pairs gave preference to patches larger in area and diameter. Nest-site selection peculiarities are explained by birds’ balanced efforts...

Colonial and Associated with Coot (Fulica Atra) nesting in Great Crested Grebe (Podiceps Cristatus): Comparison of Three Lakes

Nesting of the Great Crested Grebe in loose colonies and in close association with the Coot was investigated in Lakes Meteliai and Obelija in 1983–1986 and 1999 and in Lake Žaltytis in 1984–1986. Particular lakes and years were considered as integrators of between-lake and between-year differences in breeding habitat characteristics and were used as nominal variables. The Chi-square analysis revealed significant relations between the rates of colonial and associated nesting on the one hand and the lake and the year of breeding on the other. The share and the total area of helophytes growing in 26–100-cm-deep and 11–50-stems/m2-density zones (indices of prime breeding habitat) were used to interpret the results of between-lake comparisons. Annual differences in emergent vegetation areas dependent on winter survival and lake water level were used to interpret the results of between-year comparisons.

Impact of Air Temperature and Breeding Habitat Quality on the Beginning of the Breeding Season in Great Crested Grebe (Podiceps Cristatus)

Impact of environmental conditions on the beginning of the egg laying season was investigated on Lakes Dusia, Meteliai, Obelija, and Žaltytis in southern Lithuania. On lakes with optimal breeding habitat quality, the average 24-h air temperature influences the initiation of clutches and it starts one week earlier; the share of the nests with the first egg laid in April is more than twice higher in the year with predominant temperatures exceeding +10°C in the pre-nesting season than in the years with lower temperatures in the pre-nesting season. On the lakes with poor breeding conditions, however, the beginning of the breeding season depends on the recovery of plant cover after winter, and it is from 0.2 to 1.5 months later. Correct selection of study sites is essential from the methodical point of view. Investigation results are discussed in relation to peculiarities of the breeding biology of Great Crested Grebe.

WATERFOWL OF THE LARGE FISH POND SYSTEMS IN LITHUANIA

Abstract The aim of this paper was to provide an overview on status, abundance, distribution, habitat use of the dominant waterfowl species in large Lithuanian fish pond systems and to evaluate effects of managed temporary drainages of ponds on waterfowl. In Lithuania large fish ponds are supporting numerous species of rare breeding waterbirds, included into the national Red Data Book. Certain fish ponds are meeting criteria of the Ramsar Convention. In many areas with intensive agriculture and low carrying capacity of natural wetlands large man-made fish ponds are the key feeding, moulting and roosting sites for populations of waterfowl and shorebirds. Seasonal waterfowl assemblages in the largest fish ponds are dominated by 12 abundant species: Great Crested Grebe, Grey Heron, Cormorant, Mute Swan, Whooper Swan, White-fronted Goose, Mallard, Teal, Wigeon, Pochard, Hifted Duck and Coot. Habitat use of the dominant waterfowl species is closely related with the effects of a managed temporary drainage of po...