of the Azov-Black Sea Ornithological Station
This study for the first time presents a comparative assessment of food supply for tundra waders at stopovers in lyman-lagoon systems of the Azov-Black Sea coast of Ukraine. We observed a higher biomass of forage macrozoobenthos at the lymans compared to Syvash lagoons. However, the highest food capacity was registered at Eastern Sivash. Distribution of all resources of forage macrozoobenthos over the studied water bodies is first of all determined by sizes of sites, available for wader feeding, and chiefly concentrated in lagoons of Eastern and Central Syvash.
Distribution of available food resources of lymans and lagoons has determined location of waders on stopovers. A major part of the tundra migrants, following along the Mediterranean route across the Azov-Black Sea coast, stopped at Sivash lagoons. Distribution and high numbers of tundra waders (mainly of flock species) at Syvash were determined by presence of vast feeding areas which under any hydrological conditions could provide birds with necessary quantity of food during rather long period of time.
Low numbers of tundra waders at lymans can be explained by a small area of available feeding sites which made it impossible for big flocks to feed or stay for a longtime.
Food conditions of lymans and lagoons of the Azov-Black Sea coast provide replenishment of energetic reserves of tundra waders in any period of migrations and at the same time determine distribution of migrants. Decline in numbers of tundra waders at Syvash and lymans in recent years are determined by decrease in food capacity, changes in structure of bottom coenoses, and reduction of the areas available for feeding. Observed changes in conditions of rest and feeding on stopover sites of South Ukraine, especially at Sivash (one of the most important areas along the Mediterranean flyway) can seriously affect the population state of tundra waders which use strategy of long-distant flights.Read the paper in a PDF file