Hen harriers were first recorded at Langholm in the 1980s and for several years there were between 2 and 5 pairs. The hen harrier is the qualifying feature of the Newcastleton Hills SPA and the site is of international importance for this species. Other large predatory birds which regularly breed at Langholm include the peregine and the raven.
Numbers of hen harriers rose rapidly during the Joint Raptor Study but declined back to earlier levels afterwards. Some changes in harrier numbers and breeding success are caused by changes in vole and meadow pipit numbers which are their principal prey and which influence where they settle on the moor in spring.
Numbers of hen harrier 'pairs' breeding at Langholm (red line). In some cases male harriers paired with more than one female, so here each female is counted as a pair. Green bar chart shows number of harrier chicks fledged at Langholm since 1992 (right axis).
During the project the number of hen harriers breeding is being recorded by watching for displaying males from a series of vantage points. Harrier chicks are counted and ringed. In 2008 there were two successful pairs which raised 9 chick between them.
Food is provided to all known territories from late-March until the incubation period begins and then continued when the hen harrier chicks hatch, in an attempt to divert hen harriers away from predating on red grouse chicks. This method, which was trialed in 1998 and 1999, reduced by up to 86% in the numbers of red grouse chicks fed to hen harrier brood. It did not, however, lead to an increase in grouse stocks.
Dispersal and Tagging
The dispersal patterns of harriers in Scotland is generally not well understood, despite this having a probable influence on their survival and predation on prey during the winter. Since 2010 a proportion of the harrier chicks fledged at Langholm have been fitted with satellite tags which monitor their progress during the next year.
The project has supported this because the more is known about the dispersal and fate of harriers the better to inform national conservation frameworks. We are particularly interested in the proportion of harriers that disperse and/or die naturally away from grouse moors as this is currently not known.
Some of the dispersal movements have been remarkable. One male chick, (now known as 'McPedro') overwintered as far away as the north coast of Spain in 2010-11, returning to SW Scotland in May 2011. Click here to see the path taken by this wanderer.
This male bird and two satellite tagged chicks from the two 2011 nests at Langholm have been followed through 2011. Signals from all three birds have now ceased, one in the Scottish Borders and two in northern France. As no remains or tags have been retrieved it is not possible to establish the fate of the harriers.
Click here to see the final positions in France of the harriers tagged at Langholm.
Natural England have led on this part of the project and their public relations team can be contacted here.
There are sometimes noticeable numbers of buzzards hunting the moor at Langholm and the number of pairs breeding in the area has increased since the Joint Raptor Study. The Project wishes to understand whether this predator is having an effect on the survival of moorand birds and has commissioned work in 2011.
The first report on this work is available here.