Strong decrease of waders Charadrii in central southern Sweden during the last 50 years

Sven G Nilsson

doi:10.34080/os.v28.19530

Abstract

The number of territories of waders were counted in an area of 460 km2 around 56°37'N; 14°20'E. The most important breeding sites for waders were closely monitored in several years, 1969–1981 and again 2015–2018. Most species declined strongly, with the exception of Charadrius dubius which colonized exploited peat bogs without vegetation and open man-made gravel surfaces. Some mires were drained in the ﬁrst study period, which can explain up to 20% of recorded population declines of some species (Pluvialis apricaria, Numenius arquata, Tringa glareola). Other likely causes are earlier hay harvest and with different methods. Abandonment of cattle grazing of pastures on many small farms also occurred between the study periods. Several wader species forage on wet pastures. Predation on small young of waders may have increased. The crane Grus grus has increased dramatically in the study area and small young of waders most likely is part of the food of cranes. Changes at foraging sites during migration and in winter may be contributing causes of wader declines as well as climate change.

Highlights

The number of territories of waders were counted in an area of 460 km2 around 56°37’ N; 14°20’ E
Some mires were drained in the first study period, which can explain up to 20 % of recorded population declines of some species (Pluvialis apricaria, Numenius arquata, Tringa glareola)
Abandonment of cattle grazing of pastures on many small farms occurred between the study periods

Summary

Småspov Numenius phaeopus

Drillsnäppa Tringa hypoleucos noga för tofsvipa, enkelbeckasin, storspov, skogssnäppa, grönbena och rödbena (Nilsson 1982). En systematisk inventering av 90 öppna högmossar och 299 större kärr i Kronobergs län åren 19751980 gör att den dåtida utbredningen av arter som ljungpipare, grönbena och rödbena är väl känd i regionen (Nilsson 1979, 1981, 1986). Dessa stora sjöar har inte kunnat inventerats lika noga under senare år, varför antalet par av drillsnäppa är osäkert under 2000-talet. Olika delområden av Möckeln har dock återinventerats genom spaning från stränder och minskningen bedöms med antagandet att förändringen för drillsnäppa varit lika i övriga delar av sjön. %. Åtminstone storspov och grönbena minskade redan under 1970-talet Dessutom minskade eller försvann dessa två arter redan tidigare på flera kärr- och gungflyområden i Stenbrohult som jag inventerade under.

Vakö myr

Findings

Summary