Habitat selection by breeding curlews (Numenius arquata) on farmland: the importance of grassland

We examined habitat composition of territories, habitat use during foraging, and nest-site selection in the curlew Numenius arquata in two arable farmland areas in western Finland 1996-1997. Tall vegetation types, especially grassland, occurred more frequently within territories than expected by their availability. Habitat utilisation during foraging was significantly non-random in one of the two study areas where tillage was preferred to taller vegetation while in the other area curlews appeared to prefer tall vegetation. In both areas curlews showed a marked preference for taller vegetation types and avoided short vegetation (tillage) when selecting their nest-sites. Individuals also appeared to avoid nesting close to forest edges and ditches although this pattern was not significantly consistent between years. Breeding dispersal (the extent of movements between years) was high in the study area where curlew density was low and nest predation was frequent. In this area, breeding dispersal was higher among pairs that had failed in their previous breeding attempts than among successful pairs. Curlews preferred habitats which are relatively uncommon in an intensive agricultural regime, and we suggest that lack of suitable habitats in intensively cultivated farmland areas may be one reason for poor reproductive success and decline of curlew populations in Finland.

Valkama, J., Robertson, P. & Currie, D.1998, Ann. Zool. Fennici 35: 141-148