Hen Harrier numbers drop over 25% in Special Protected Areas

Hen Harrier populations in several of the designated Special Protected Areas (SPAs) have declined 26.6% since 2005, the results of the the 2015 National Survey of Hen Harriers show.

John Lusby, Survey Coordinator with BirdWatch Ireland said that the fact that the SPA network holds 44% of known pairs in the country, which is a significant proportion of the population, shows just how important these areas are in the national context.

“The current survey results confirm that populations within parts of the SPA network are declining and without intervention through appropriate management further declines at certain sites are anticipated.”

As a requirement under the EU Birds Directive in 2007, Ireland designated six sites as SPAs based on their national importance for breeding Hen Harriers.

Birdwatch Ireland has said that management of this SPA network requires that Hen Harrier populations are maintained and enhanced while also being compatible with stakeholder requirements.

It also said that supporting farmers and landowners, particularly within SPAs, to manage their lands using traditional and sustainable practices is key to Hen Harrier conservation.

The survey suggests that the decline of Hen Harriers may be linked with declines in availability of their preferred habitat, changes in habitat quality and associated effects on food availability.

Furthermore, it found that it is likely that land-use changes over the past 50 years, which may have resulted in an increasingly fragmented and/or unsuitable landscape for upland breeding birds, may be impacting on the Hen Harrier.

Overall, the survey found that the current national population estimate of 108-157 breeding pairs in 2015 represents a decline of 8.7% since the 2010 national survey which recorded 128-172 pairs.

Due to the increase in survey effort in 2015, Birdwatch Ireland has said that the most accurate assessment of national population trends can be calculated through a comparison of Hen Harrier numbers in specific survey squares which were covered across the various national surveys.

These results indicate a decline of 16.4% in the national Hen Harrier population since 2010 (based on assessment of Hen Harrier numbers recorded within 139 10km squares surveyed in both 2010 and 2015) and 9.7% declines since 2005 (based on 110 10km squares covered in 2015 and 2005).

A comparison of the survey area (78 10km squares) which was covered in all four national surveys (since 1998) indicates that the population has fallen from 110-155 pairs during the first national survey in 1998 – 2000, compared with 95-130 pairs in 2015, which is an overall decline of approximately one third (-33.5%) over this 15 year period.

As one of Ireland’s rarest birds of prey, Birdwatch Ireland has said that the long-term declines in Hen Harrier populations provides cause for concern, particularly given the important role this species has to play in our wild and rural landscapes.

Dr. Allan Mee, Survey Coordinator with the Irish Raptor Study Group, said that there was a wide range of different pressures recorded in the national survey both within and outside SPAs, and many of these warrant further investigation.

“Pressures such as forest maturation, clear-felling, wind energy production, agricultural intensification, uncontrolled burning and degradation of important open habitats such as heather moorland, turf cutting, and recreational disturbance were all recorded by observers during the study.

“It is important to understand why some harrier populations may be declining and thus a comprehensive and scientifically robust action plan is needed to maintain or enhance existing Hen Harrier populations into the future.”