Hen Harrier Circus cyaneus


Justification of Red List Category
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (extent of occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population size has not been quantified, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). The population trend is not known, but the population is not believed to be decreasing sufficiently rapidly to approach the thresholds under the population trend criterion (>30% decline over ten years or three generations). For these reasons the species is evaluated as Least Concern.

Population justification
The European population is estimated at 30,000-54,400 breeding females, which equates to 60,000-109,000 mature individuals (BirdLife International 2015). Europe forms approximately 34% of the global range, so a very preliminary estimate of the global population size is 176,000-321,000 mature individuals, although further validation of this estimate is needed. It is placed in the band 100,000 to 499,999 mature individuals.

Trend justification
The population trend is difficult to determine because of uncertainty over the impacts of habitat modification on population sizes. However in Europe the population size is estimated and projected to be decreasing at a rate approaching 30% over the period from 2000, when the decline is estimated to have started in Russia, which holds 70% of the European population, to 2024 (three generations) (BirdLife International 2015).


The current main threat is the transformation of habitat owing to intensified agriculture, disappearance of marshes and reafforestation. Persecution is still severe locally, for example on managed grouse moors of Scotland; in 2013 not a single pair successfully nested in England (Pitches 2013), despite the fact that there is estimated habitat for more than 300 pairs (Fielding et al. 2011). The species is also shot illegally in central and eastern Europe (Tucker and Heath 1994). In the Czech Republic, wild boar Sus scrofa may pose a major threat to nesting birds (Kren 2000 in Global Raptor Information Network 2015).


Text account compilers
Butchart, S., Ekstrom, J., Symes, A., Taylor, J. & Ashpole, J

Recommended citation
BirdLife International (2021) Species factsheet: Circus cyaneus. Downloaded from on 26/01/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from on 26/01/2021.