The hen harrier is a bird of open habitats such as heather moorland, a type of vegetation which is typical of the reserve.

Although such habitats are common in the uplands of England, the bird is scarce, being illegally persecuted as a predator of red grouse.

[2] The black grouse requires a more varied habitat than the hen harrier and the RSPB has planted many trees at Geltsdale.

Another bird of interest is the curlew, which since 2020 has been supported in this part of northern England by a project funded by the European Union's LIFE programme.

Bonny was satellite tagged as part of a project funded by the European Union's LIFE Programme, "Conserving the hen harrier (Circus cyaneus) in northern England and southern and eastern Scotland" (LIFE13 NAT/UK/000258).