The paper considers features of Waders distribution during their stopovers at the half-closed estuary, being the wetland of international importance - Molochny Liman, the Sea of Azov. Molochny Liman stretches meriodionally (its length about 36 km), shores are asymmetric: the fight bank is higher and steeper; the left one is more gradual and boggy-patched.
In 1960s P.P. Orlov (1965) for the first time mentioned 27 Waders species for Molochny Liman. More detailed data about Waders are presented in the works of V.I.Lysenko (1968, 1970, 1974, 1975, 1980, 1988, 1988a, 1992) who mentioned 31 species.
The materials were gathered over the period 1971-1975 and in 1986-2002 by the authors of this paper and other staff of the Azov-Black Sea Ornithological Station.
They also were completed by archive materials of K.P.Tilonov of 1969. Absolute census of Waders was taken according to the standard method (Novikov, 1953) along the fixed routes and separate monitoring territories, reflected landscape in features of the liman. 286 counts were taken (Table 1). Special observations were carried out during 1987-2002 according to Kumari's method (1955). Catching of Waders was fulfilled over the period 1986-1996 and 2001-2002 with using mist nets. In total 644 Waders of 16 species were caught. The captured birds were measured by the standard method (Prater et al., 1977), the results are summarized in Table 2 and discussed in special species reviews.
Results and discussions
Principal habitats used by migrating Waders. The embayment of the coastline and numerous accumulative bodies of the liman expand the area of feeding habitats for Waders. Shallowness and salinity of the liman favour formation of rich bottom communities of macrozoobenthos. According to the data of special surveys (Kirikova, 1998), such communities are productive and provide the biomass available for leaders as 2.25 – 19.05 g/m2. Basing on the liman special characteristics we chose principal types of habitats used by Waders (fig.1). To them we should also add agrocoenoses adjacent to the liman that are important for some Wader species. Both the liman landscape diversity and differences in Waders location cause the necessity to divide it into monitoring territories (MT) (fig.2).
Species diversity.During the study the list of Waders at Molochny Liman was added by such species as Xenus cinereus, Vanellochettusia leucura, Limicola falcinellus, Calidris alba and Limosa lapponica. Some earlier registered species were not met at the moment. It may be explained either by decreasing of available habitats (Lymnocryptes minimus) or their status in the region as for Glareola nordmanni and Euiynorhynchus pygmeus (Orlov, 1965; Lysenko, 1974, 1992). So over the last 40 years 39 Wader species were recorded at the liman in different seasons and periods (Table 3).
Number, distribution and migration.Features of migration and seasonal distribution for 39 Wader species are considered. The data of the first and last registrations, number and information about its fluctuation throughout the year are given. Characteristics of the migration (fig. 4, 5, 10), distribution in monitoring territories are analyzed for some species. The number dynamics is shown on the example of one of the model territories, MT-VII (see fig.2) and presented the species number dynamics (fig. 3, 6, 7, 8, 9, 11, 12, 13, 14, 15).
Molochny Liman is the Ramsar site. It is one of the most valuable places of Waders stopovers in North near Azov area. In May on separate parts of the liman over 32000 birds were counted simultaneously, while in August - about 9000. There are such rare and globally threatened species among Waders as Slender-billed Curlew, Whimbrel and Curlew, Collared and Black-winged Pratincoles, Black-winged Stilt, etc.
There are registered 8 rare species, 14 non-numerous, 11 common and 4 numerous bird species.
Two species are vagrant. Average number of Waders, counted at the liman dining spring census were 3714, and autumn - 3852 individuals. The number of 14 species allows comparing spring and autumn migration. Thus Oystercatcher, Ruff Dunlin and Sanderling are characterized by more numerous spring migrations, and vise versa five species (Grey Plover, Lapwing, Little Stint, Curlew Sandpiper and Curlew) have more expressed autumn migration. Also five species (Turnstone, Redshank, Greenshank, Black-tailed and Bar-tailed Godwit) have a similar type of season migrations. In winter period at the liman only some Waders were recorded (Dunlin, Curlew, Lapwing), their number did not exceed 30 individuals.
The authors are sincerely grateful to E.A.Diadicheva, V.M.Popenko, P.I.Gorlov, T.A.Kirikova, V.V.Kinda, A.N.Falko, A.I.Koshelev, Yu.A.Andryushcenko, D.S.Oleynik, I.D.Belashkov, I.S.Mitiay, S.V.Khomenko, B.A.Gaimash, A.B.Grinchenko, G.Nikolaus, whose infonnation completed the computer database. A considerable work was fulfilled by the staff workers of Ornithological Station E.A.Isaeva and S.V.Vinokurova who also has specially developed small programs for the computer database. The authors also thank the members of the zoological section of Darwin Moscow Museum (leaded by E.S.Preobrazhenskaya), which participated in gathering materials at Molochny Liman during spring 2002.
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