PhD Project

The importance of winter ecology for the conservation management of Hen Harriers in Ireland

Hen Harrier Silhouette

Partners: University College Cork, BirdWatch Ireland, IRD Duhallow
Funding Body: National Parks & Wildlife Service
Duration: July 2018 - October 2021


Project Background
Effective conservation management of Hen Harriers (Circus cyaneus) in Ireland requires a good understanding of their ecological requirements throughout the yearly cycle. Research to date, a considerable amount of which has been undertaken at UCC, has provided a detailed understanding of the habitat and conservation requirements of this species during the breeding season from April to August. However, their ecology in both winter and breeding seasons is essential to understand the complete life cycle and to fully inform effective conservation strategies.

Research at UCC, together with research from other parts of their range, has identified important aspects of the ecology of Hen Harriers (Irwin et al. 2008; Irwin et al. 2011; Fernandez-Bellon et al. 2017Fernandez-Bellon et al. 2018; Geary et al. 2018; Caravaggi et al. 2019; Nota et al. 2019). This body of work has examined their requirements in relation to afforestation (Wilson et al. 2009; Wilson et al. 2010Wilson et al. 2012; Hayhow et al. 2013), wind farm development (Whitfield & Madders 2006Fernandez-Bellon et al. 2015Wilson et al. 2017) and agricultural intensification (Amar & Redpath 2004Wilson et al. 2006). There has been a focus on breeding biology, nesting ecology and breeding habitat requirements, but there has been little published research on the ecological requirements of this bird species outside of the summer breeding season to date (Clarke & Watson 1990), with no published data for Ireland which could inform policy and conservation management. The focus thus far on the breeding ecology of Hen Harriers to inform their conservation in Ireland ignores the opportunity for management to address the full annual cycle including post-fledging dispersal, survival and subsequent recruitment to the breeding population.

Ensuring the persistence of Irish Hen Harrier populations requires a better understanding than we presently have of their requirements throughout the year. This project was designed to investigate the over-winter, or non-breeding, ecology of the Hen Harrier and to focus resources on advanced statistical analysis of data collected from satellite tags deployed on Hen Harriers in Ireland in recent years by NPWS and the IRD Duhallow Raptor LIFE project. 


McCarthy A 2022. Seasonal Ecology and the Conservation of Hen Harriers (Circus cyaneus) in Ireland. PhD Thesis. University College Cork. 263pp. McCarthy 2022 PhD.


Project Team
Principal Investigator: John O'Halloran
Project Manager: Sandra Irwin
PhD Student: Alan McCarthy


Film strip of photos of hen harriers, depicting a male bird in flight, a female bird in flight, a female bird perched and a nest containing chicks and eggs

Forest Ecology

Dept. of Zoology, Ecology & Plant Science, University College Cork, Distillery Fields, North Mall, Cork