The success of one of Scotland’s rarest birds of prey, hen harriers, is closely linked to the age of parent birds, prey availability and land use, concludes a report published by NatureScot today.
The report, based on five years of camera evidence on 28 estates participating in the Heads Up for Harriers partnership project, found the age of the adult male bird is a key factor in breeding. There was a 91% success rate when males were older than one year, irrespective of the age of the adult female bird.
Not surprisingly, the report also found that nesting attempts and fledging success were higher during warm, dry spring weather, with wetter weather having a negative impact on both the harriers and availability of prey.
The research also found that hen harriers prey were birds 89% of the time with mammals making up the final 10%. However, the report concludes that hen harriers rarely prey on grouse. Meadow pipits were by far the most abundant prey at 77% of birds, with red grouse accounting for only 5.6% of prey.
Over 2 million hen harrier nest camera images were meticulously studied to reveal harrier behaviour and factors impacting their survival. While the majority of estates have some game shooting interest, analysis indicated that harriers fare best on those estates with no shooting interests, with more breeding attempts, nesting success and higher productivity recorded on the majority of non-sporting estates.