Abstract

Merlins Falco columbarius breeding in the Lammermuir Hills, in southeast Scotland, were studied from 1984 to 2014 in an area of heather moorland managed intensively for driven grouse shooting. Over 30 Merlin territories were surveyed in most years to assess levels of occupancy, and evidence of nesting and productivity. From 1984 to 2006, 12-21 (mean 14.7) occupied territories were found each year, but during 2007-14 this declined to 8-10 (mean 8.6) territories. The number of nests found showed a similar pattern: 7-13 (mean 8.7) and 3-8 (mean 6.0) respectively. Over 96% of nests were on the ground in heather Calluna/Erica, with the remainder in trees in old Carrion Crow Corvus corone nests. The median first-egg date was 3rd May and mean clutch size was 4.41 (range 1-6). Other upland birds were ringed during the study period, with relatively constant effort from 1992 to 2014; in that period, the numbers ringed declined steadily. In the last decade or so of the study, land management for driven grouse shooting intensified, including the frequency of heather burning and the use of predator control. More hill tracks were built to service windfarm developments. Contributing factors to the decline in Merlin numbers may include failure to return to breeding areas (perhaps because of reduced overwinter survival) but factors at play on the breeding grounds are probably most important, notably the effects of moorland management in the study area, for example through availability of suitable nest sites and on the Merlin's favoured prey species.