The breeding ecology and decline of the merlin falco columbarius in orkney

Abstract

The Merlin population in Orkney has undergone a marked decline during the 1980s. Site occupancy fell from 42% to 14% between 1981 and 86, while mean breeding success fell from 48% during 1975-81 to 29% during 1982-86. Mean brood size of successful nests declined from 3.3 during 1975-80 to 2.5 during 1981-87. Most breeding failures occurred during incubation. Loss and degradation of habitat, disturbance, weather, predation, organo-chlorine contamination and mercury contamination were examined as possible causes. © 1988 Taylor & Francis Group, LLC.