Changes of nesting bird fauna at the Engure Ramsar site, Latvia, during the last 50 years
2000
Viksne, J. (University of Latvia, Riga (Latvia). Inst. of Biology)
Bird fauna of Lake Engures, Latvia, and its surroundings has been studied since 1948. Altogether 186 nesting species have been recorded, and major quantitative changes (vanishing, decline, increase, appearance) have been observed in at least 71 (38.2%) of these species. The number of species with negative trends (44) exceeds that with positive trends (27). Habitat succession was found as the most important cause for negative alterations, while shifts of breeding range were the most important cause for positive alterations. Species of southern origin prevailed among newcomers, while those of northern origin - among vanished species. Especially pronounced changes were observed beginning from 1992/1993 till the late 1990s when breeding duck numbers declined from 2620 to 1000 pairs and Black-headed Gull numbers from 34,000 to 6000 pairs. Causes for the changes are discussed.
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