Low productivity of curlews Numenius arquata in southern Finland: causes and consequences

Abstrakti

We monitored population changes and breeding success of Curlews Numenius arquata in a 18 km2 arable farmland area in southwestern Finland over a four-year period (1995-1998). During this time, the breeding population decreased from 30 to 23 pairs (23% decline) . The majority of breeding failures took place during the incubation (57/ 84, 68%), and further losses occurred during chick rearing period as a result of which only 20% (17/84) ofverified breeding attempts produced fledglings . There were 17 pairs (more than half of the breeding population) that failed in their breeding attempts every year . The overall reproductive success was 0.32 fledglings/pair, which was calculated to be too low to maintain astable population . Nest predation (81%) and nest losses due to agricultural practices (16%) were the most important reasons for failed breeding attempts . We suggest that continual breeding failures (especially due to nest predation) may be the most important reason for the observed decline of Curlew populations in southern Finland.