Changes in the breeding bird fauna, waterbird populations in particular, on lake engure (Latvia) over the last 50 years

The nesting bird fauna (186 species) of Lake Engure and its surroundings has changed considerably over the last 50 years: 18 species have appeared as newcomers (among them 56% of southern, 6% of northern origin), 10 species have ceased nesting (among them 60% of northern, 10% of southern origin). These changes might be explained by global warming. Dramatic changes recorded in all waders can be accounted for by the local habitat loss and a general decline in wider geographic ranges. The Black-headed Gull (Larus ridibundus) population increased from 200 pairs in 1940s to 34,000 pairs in 1986, and then declined to 4,200 pairs in 2002. Nesting duck (all species combined) numbers and their nesting success increased significantly in 1958–1993 but showed sharp significant decline in 1993–2004. Unfavourable changes in vegetation caused by the merging of separate stands of emergents into huge uniform swards dominated by common reed (Phragmites australis), and a decrease of areas covered with meadow vegetation had a negative effect on all waterbirds.