SEEN - SE European Bird Migration Network
The ringing activity of the field ornithological camp "Avosetta" (Western-Ukrainian Ornithological Station, 1995-2009)
Hnatyna O., Shydlovskyy I.
Lviv Ivan Franko National University, Zoological museum, Ukraine

The ringing activity on the base of the Western-Ukrainian ornithological station started in 1995 on the territory of the technical ponds former industrial union “Syrka”. The company stopped its activity in 1993, leaving attractive habitats for migratory birds. To save these habitats for birds, a local ornithological reserve “Cholhynskyy” was created in 1997. Its area is 820 ha. On the territory of the reserve two technological ponds parted by dam are placed. They are surrounded by pastures. Annual bird catching lasted from early August to early September, in some years – to September 15 (1995) and from 11 July (1999), from 16 August (2006). Passerine birds were caught with “mist” nets, which were placed in the reedbeds on the bank of the overgrowing pond. On the pond’s shallow the walking traps for catching waders were placed. 31 736 birds of 115 species have been ringed for the entire period of activity. Since 1997 till 2001 the number of caught passerine birds increased. The number of caught passerine birds decreased rapidly in 2002-2003, and in 2004 this number was gradually decreasing. Their number was the lowest in 2009.

Eventually, the population’s trends reflect in the number of birds caught during migration, but in this case, the main reason for declining of the numbers of birds is feeding habitat changes. During last few years the decreasing of water level in ponds that resulted in plant succession is clearly visible. The amount of water in the ponds is constantly decreasing, pastures overgrowing with Calamagrostis (as a result of a reduction of the cattle grazing intensity), banks are overgrowing with reedmace (Typha), and reedbeds around the pond became more dispersed and lower as well transformed from monodominant ones into plant associations with the dominance of the common reed (Phragmites communis), the Coltsfoot (Tussilago farfara), willows (Salix) and other plants. Thus, in the catch, since 2005, the share of the Whitethroat (Sylvia communis), and such species as the Blackcap, Garden Warbler, Lesser Whitethroat (S. atricapilla S. borin, S. curruca) began to increase. They did not occur or were rare in the previous years but since 2004 they became not numerous, but common. The share of the Marsh Warbler (Acrocephalus palustris) and the Red-backed Shrike (Lanius collurio), which prefer plots with the presence of willow trees, also increases. During the last five years the following species were caught more often: Erithacus rubecula, Ficedula hypoleuca, Luscinia luscinia, Parus major, P. montanus, Passer montanus, Phoenicurus ochruros, P. phoenicurus, Hippolais icterina, Luscinia svecica. During the last three years the share of the Great Reed Warbler (Acrocephalus arundinaceus) and Savi's Warbler (Locustella luscinioides), that prefer monodominant reedbeds during migration, has decreased. Reducing of the water table and vegetation-free shallow areas, have made it almost impossible for the considerable quantity of waders to rest, feed and roost. Recently, the most numerous of the abovementioned groups is a wader’s genus (Tringa), in particular Wood Sandpiper               (T. glareola). The rapid decrease of the water level and almost sudden overgrowing of the coast with a high grass made these sites unsuitable for the feeding of some birds (Charadrius sp., Calidris sp.). The Avocet (Recurvirostra avosetta) does not nest here any more.

The uncontrolled reed burning by local people in winter and spring is also one of the negative factors. Burning of the small areas generally do not bring a negative impact on feeding habitat for migratory birds, but burning of the extensive area and, particularly, burning in the early nesting period, has a significant negative impact due to dispelling and direct threat to their lives. The results of the current year birds catching confirm this issue. The last year’s reed stalks are important as feeding biotopes for: Emberiza schoeniclus, Acanthis cannabina, Remiz pendulinus. That is why burnt areas become unsuitable for them. The share of the Yellow Wagtail (Motacilla flava) and swallows (Hirundo rustica, Riparia riparia) has decreased most of all due to the changes in feeding and roost habitats of this species. The overgrowing of the pastures with Calamagrostis and dense high grass has made the area of the reserve unsuitable for the foraging wagtails. The excessive loss of moisture and poor and clay soils composition promote further overgrowing with Calamagrostis. The changes and loss of the roost habitats of wagtails and swallows are associated with water loss as well as with the reedbed degradation, that are constantly exposed to burning every spring (April-May). The late spring reed burning leads not only to a direct negative effect on birds, but also to the fact that the reed can not recover completely even throughout the growing season.

Headlong decline in the number of migratory bird in the reserve due to habitat changes concern the ornithologists very much. It threats the existence of one of the most interesting areas in terms of fauna of the nature conservation fund (NCF) of the region – Ornithological Reserve “Cholhynskyy”. Theoretically, we have found a way to save the reserve, and thereby a large number of birds that for fifteen years have been found here during migration (near 100 thousand of birds during the season). On the one hand, it is difficult to stop natural processes, but the uncontrolled burning of reedbeds has a direct and indirect negative effect on the state of the reserve. Therefore to penetrate the well, which would give an opportunity to provide reserve water is badly needed in the near future.

Secondly, it is necessary to improve the nature conservation status of the reserve as an object of NCF and submit it to the jurisdiction of the National Park "Yavorivskyy". It will give the possibility to provide more effective supervision over valuable and vulnerable ecosystems.
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