The likelihood of hen harriers in Britain disappearing increases with their use of grouse moors as a habitat according to a study involving data from 58 satellite-tagged harriers. The findings are published in Nature Communications this week.

Arjun Amar, Megan Murgatroyd and colleagues used satellite-tracking devices and remotely sensed habitat and land-management data to test whether the deaths and disappearances of hen harriers were associated with land managed for shooting red grouse (grouse moors). Of the 58 hen harriers included in the study, 38 disappeared (their tags suddenly stopped transmitting without any prior evidence of malfunction and remains of the harriers were not recovered) and four birds died as a result of illegal killing. The authors found that there was an association between the death or disappearance of tracked hen harriers and the use of grouse moors. They observed that satellite fixes of the birds from the week prior to their disappearance showed a disproportionate use of grouse moors in comparison to their overall use of such areas.

The authors argue that, despite the lack of physical evidence, this would suggest that the tags were destroyed and the disappearance of the birds is most likely the result of illegal killing.