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Aves, 40/1-4 | 2003 | 205-206

  Will the Black Stork (Ciconia nigra) remain as a breeding species in Estonia?
Sellis, U.

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Article summary

The Black Stork is at the north-western border of its distribution range in Estonia. This paper summurizes data on its numbers and distribution in Estonia in 1999, reproductive success in 1991-2000 and resluts of the special bird of the year project in 1998. The latter, which was aimed at rising public awareness and gathering additional data, resulted in three new nest sites and a total of 62 territories counted. The main result, however, was information success: in the public opinion the Black Stork was among the most well known protected species in 1999. The numbers were estimated at 100-120 pairs in 1999, which is 2-2.5 times less than two decades ago. Distribution concentrated into the largest forested areas rich in rivers and streams. The population decline coincided with low productivity in the last decade, on the average 1.05 young per occupied (with at least some nest-building activity recorded) nest and 44% of nest sites successfull. Trends in all reproductive criteria were negative (although not statistically significant); except the number of dead youngs in nests, which was highest in the years of summer droughts (1994-1997, 2000). Most probably the reasons for decline and poor reproduction are in our breeding grounds, because some other populations that use the same migration route and wintering areas are increasing. Productivity in the neighbouring countries is a poor as here, thus, there is no potential for immigration. Typically for a declining population, the reproductive rates in Estonia fluctuated widely between years. Therefore, it is important to monitor the population every year. However, in the 1990s state-monitoring program covered the Black Stork only in 1994 and 1999, which are not representative yearsn as these happened to be the best years for breeding. In general, the status of the Black Sork in Europe is alarming. Decreases in the previous source-populations of Poland and baltic states are not comensated by increases in other, much smaller, populations. For conservation, it is important to find out the reasons of declines, which probably will be successfully achieved only by international cooperation.

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