Surveys of the birds in the Rautas area in 1978 and 2001—population changes in an alpine area

Abstract

The breeding bird fauna of the Rautas mountain area, south of Torne träsk in northern Sweden, was censused in 1978 and 2001. Sixtyseven 2x2 km squares were censused along 9.6 km transects within each square. Thirtyone of the 63 analysed species showed no significant population changes, 20 species had decreased significantly, and 12 species had increased significantly. Among the increasing species were: Short-eared Owl Asio flammeus, Long-tailed Skua Stercorarius longicaudus, Redpoll Carduelis flammea, and Whimbrel Numenius phaeopus. Among the 20 decreasing species were: Golden Plover Pluvialis apricaria, Red-throated Pipit Anthus cervinus, Bluethroat Luscinia svecica, and Lapland Bunting Calcarius lapponica. A Correspondence analysis revealed that a relatively large proportion of the species in alpine heathlands had decreased, while there was a mixture of stable, increasing and decreasing species at the woodland and wetland end of the gradient. A possible explanation to the observed population changes could be an increasing number of reindeer in the Swedish mountains since the 1970s, since overgrazing can affect both the availability of nest sites and food negatively.