Branta Issues > Issue №11 (2008)

The Cormorant in the North-Western Caucasus

M.A.Dinkevich, R.A. Mnatsekanov, T.V. Korotkiy, I.S. Naydanov

The present paper summarized all known literary and unpublished data obtained from the regional ornithologists, workers of hunting organizations of the Krasnodar Region and also author's original materials on distribution, numbers and some aspects of biology of the Cormorant in the North-Western Caucasus (the areas of Krasnodar Region and Adygeya Republic). The author's original data have been collected over the period from 1989 to the present time. Data on the breeding numbers were obtained by a method of complete registration of nests in the colonies, mainly during the nesting period (April - June) and at times - after the breeding season (July - August) or sometimes - on a basis of expert estimation of the adult bird numbers. Cormorant colonies at the Khanskoe Lake (1996, 1999-2000, 2004, 2006) and within the Kiziltashskie Limans (1989-1992, 1995, 1998, 2006-2007) have been surveyed oftentimes and sharp increase in the species numbers was observed over the last years. Researches of key Cormorant areas have been carried out in frame of the expeditions of Kuban State University (1989-1991, 1995-1996) and during performance of the different projects ("Pelican-99"; BP Conservation Programme, 1999; PINMATRA on Key Ornithological Areas of the Krasnodar Region, 2004; CEPF and WWF "Site network for birds and wetlands: inventory, protection and community management", 2006).

Ringing data on Cormorants breeding in reed-beds of the Kuban River (Kochkovatyi, Solodko-Ryasnoy and Kirpilskiy Limans) were analyzed by publications of N.N. Skokova (1978) and E.V. Zubakina (1991). The total of 81 ring recoveries from the Cormorants ringed as nestlings in 1961, 1964, 1968, 1974 and 1981 has been analyzed. Additionally 68 more recoveries from the Cormorants ringed as juveniles in the Ukraine (Obitochnaya Spit, Molochnyi Liman, Sivash, Lebyazhy Islands) over the period 1979-1999 and observed on migration in the North-Western Caucasus (Мациевская, Кошелев, Дядичева, 1998; Мациевская et al., 1999) have been processed. Data on wintering Cormorants were collected during the mid-winter bird censuses over the seasons 2003-2008, carried out mainly in frame of the International waterbird census (IWC) (WWF Project "Towards a strategy for waterbirds and wetland conservation in the Central Asian Flyway").

Main breeding sites of the Cormorant are located in limans and reed-beds of the eastern part of the Sea of Azov region and in the northern Black Sea region, where concentrations of mass fish species are known. Within this area only 2 types of the Cormorant settlements are discovered: 1) ground type of breeding on sand-shell islands and spits and 2) breeding on reed breaks in thickets of macrophytes. The first kind of breeding is typical for the large and well-being colonies of the Cormorant. Nesting on trees in the North-Western Caucasus is known only by the literary data.

Till the middle of 1970s Kuban Delta was the only place of Cormorant breeding in the whole North Caucasus region, including the Krasnodar Region in particular. Numbers of the breeding Cormorants fluctuated from 400-500 to 1000-1500 pairs that could not cause damage to fish industry in the eastern part of the Sea of Azov region.

Since the end of 1970s sharp increase of the Cormorant numbers was noted everywhere in the North-Western Caucasus, because of the intensification of fish-farming, extension of the areas of fish-farms in the Kuban Delta and outside it, and also due to growth of populations of some fish species, including acclimatized ones (Mugil so-iuy Basilewsky). Decrease of natural populations of the most prey species of fish in the Kuban Delta caused a displacement of the Cormorant colonies to the new, rich in fish water bodies (Khanskoe Lake, Kiziltashskie Limans, Yeyskiy Liman) and a forming of new trophic connections between the Cormorants and artificial water bodies. The Cormorant began to cause a significant damage to fish-farming at the beginning of 1980s. The damage to fish industry, caused by birds is not essential, when their natural prey is numerous. In 1990s there were 9490 breeding pairs of the Cormorant in Krasnodar Region, at the beginning of 2000s - 8500-11000 pairs and at present - already 13000- 18000 pairs. The largest colonies are known at the Khanskoe Lake (4000-5000 pairs), Kiziltashskiy (about 3000), Yeyskiy (about 3500), Boykievskiy (2000-2500) Limans and in the Dinskiy Bay (about 2000).

The Cormorant often becomes a dominant (co-dominant) species in structure of island ecosystems of the eastern part of the Sea of Azov region and the northern Black Sea region and exerts a significant influence on populations of other birds breeding side by side.

The Cormorants breeding in the Kuban reed-beds are characterized by a strong fidelity to their nesting sites (nesting conservatism).Birds stay in the Sea of Azov region till late autumn and spend winter in the Azov-Black Sea basin, mainly at the northern and eastern coasts of the Black Sea. This population has short-distance migratory routes (usually not more than 100-120 km from the breeding sites in all seasons), and their passage looks like gradual migration from place to place. Ringing data don't show significant age differences in seasonal distribution and migration pattern of the Cormorants. Besides the local individuals, birds from the other populations (subpopulations) from the South Ukraine (Sivash, Molochnyi Liman, Obitochnaya Spit, Lebyazhy Islands) and, sometimes, from the Volga Delta, and even from the Aral Sea also migrate in the North-Western Caucasus.

At the first half - middle of the 20th century the Cormorant was a rare, irregular wintering species in the region. Numerous wintering areas start to form only since 1960s. Main part of the population passes winter at the Black Sea but not at the Sea of Azov coast, within the water reservoirs bird numbers are small. The greatest wintering numbers are noted at the Kiziltashskie Limans and in the Novorossiysk Bay. Since 1970s the wintering areas begin to form in the central part of the North-Western Caucasus (near Krasnodar). During the winter period the weather conditions and fish distribution influence displacements of the Cormorants. Within the fish-ponds area daily movements of the Cormorants are regular – from the roosting places to ponds and back.

Main efforts, made in the region to reduce a negative influence of the Cormorants are the following: shooting, extermination of clutches in the colonies, frighten off by sound and visual repellents and biotechnical measures. The last method (coincidence of terms of putting fish fry to ponds with terms of mass movements of fish of little value) show itself to advantage in the fish-farms of the eastern part of the Sea of Azov region.

At present in the Krasnodar Region (as well as in the whole South Russia and Ukraine) it is necessary to elaborate and carry out a long-term program on management of the Cormorant population, based on monitoring of state of some settlements of this species and their influence on the fish resources, first of all within the fish-farms.