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 does not 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). Although the population is suspected to be decreasing, the decline is not believed to be sufficiently rapid 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.
The European population is estimated at 56,300-86,600 breeding females, which equates to 112,000-174,000 mature individuals (BirdLife International in prep.). Europe forms approximately 34% of the global range, so the global population size is suspected to number 330,000-512,000 mature individuals, although further validation of this estimate is needed.
The population trend is difficult to determine because of uncertainty over the impacts of habitat modification on population sizes. The overall trend in Europe is uncertain (BirdLife International in prep.), but is suspected to be decreasing as declines have been reported across several European countries (Fernandez-Bellon et al. 2020). The species's European range has also contracted over the last few decades (Keller et al. 2020). The trend in Asian Russia is unknown.
The current main threat is the transformation of habitat owing to intensified agriculture, disappearance of marshes and reafforestation. Burning of vegetation is one of the most commonly recorded pressures in Ireland at both breeding and non-breeding sites (Caravaggi et al. 2019; O'Donoghue 2020). 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). Of 117 Hen Harrier chicks satellite tagged in the UK between 2015 and 2019, only 15 were still alive in June 2020, most having gone missing in suspicious circumstances (RSPB 2020). 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).
Conservation actions underway
The species is listed under CITES Appendix II, CMS Appendix II, Raptors MoU Category 2, EU Birds Directive Annex I, Bern Convention Annex II. In Europe, active species and habitat management strategies including nest protection, predator control and improvement of nesting and foraging habitats have been adopted in some countries (Fernandez-Bellon et al. 2020). The Hen Harrier LIFE+ Project (2014-2019) included work to raise awareness of Hen Harriers in the UK (RSPB 2020).
Text account compilers
Butchart, S., Symes, A., Ashpole, J, Taylor, J. & Ekstrom, J.
BirdLife International (2022) Species factsheet: Circus cyaneus. Downloaded from http://www.birdlife.org on 19/01/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 19/01/2022.