A study by the Game & Wildlife Conservation Trust identifies that the predator control carried out on grouse moors can benefit one of our most striking birds of prey: the hen harrier. Conducted between 1992 and 2007 at Langholm, southern Scotland, the study cited protection from predators and boosted natural moorland food supply as reasons for an increase in hen harrier productivity. But it also highlights a conservation conundrum: high densities of harriers can prevent successful management of productive grouse moors, which in the past has led to illegal control of the birds.
During the study, hen harrier numbers increased from two breeding females in 1992 to 20 birds in 1997. In 1999, grouse management and its associated predator control was stopped following heavy losses of red grouse, and the number of female harriers dropped to just four by 2002 after predator numbers increased.
Several techniques are currently being tested to mitigate the impact of harriers on grouse populations. These include introducing a ‘harrier quota’ principle, which would limit the number of young harriers in an area through non-lethal means, and diversionary feeding of nesting harriers with supplementary food such as dead rats or day-old poultry chicks.
Game and Wildlife Conservation Trust director of research, David Baines, commented, “Successful implementation of these measures on grouse moors may be a way forward to protect hen harriers. As we have shown, the control of generalist predators by gamekeepers not only helps conserve important species of ground-nesting birds and grouse but is also beneficial for our spectacular hen harrier. The argument is compelling and dialogue between shooting and conservation bodies is crucial to ensure the future of this magnificent bird of prey. It is therefore gratifying that stakeholders on both sides of the debate have recently expressed their desires to work collectively towards finding answers.”