Responses of breeding waders to restoration of grouse management on a moor in South-West Scotland

Worldwide, many wader species have recently exhibited steep declines in range and abundance. Low productivity, frequently associated with predation, is considered a major proximate driver of declines and often reflects underlying land use and habitat change. We hypothesised that restoration of grouse moor management, which includes control of predators and heather habitat management, would halt and reverse these declines. We monitored changes in the abundance of four upland-breeding wader species following restoration of grouse moor management at Langholm Moor in South-west Scotland from 2008 to 2017. Here, Curlew, Golden Plover and Lapwing had previously declined when management ceased, whereas Snipe had increased. During the 10-year study period, Curlew numbers increased on average by 10% per annum, Golden Plover numbers by 16% and Snipe numbers by 21%, whereas Lapwing numbers did not change. These local trends contrast with national and regional trends over the same period, which all showed declines of all these species. However, the population trends for Curlew and Snipe did not differ in relation to habitat management for Red Grouse, suggesting that population increases were primarily associated with predator control across the whole study area. Our results support the hypothesis that restoring predator control as part of grouse moor management can reverse declines of some wader species. At Langholm, full recovery to levels observed prior to management cessation may have been constrained by delayed recruitment within a time-restricted study period in combination with low initial numbers, availability and isolation of suitable habitat, and incomplete predator removal.