Studying Irish hen harriers can be challenging. Many of us have taken part in the most recent national survey (2015) and enjoyed some great days out, perhaps the first sky-dancing male of the season or finding a pair at a new site or the first food-pass and female returning to a nest site. All this helps to give us a more or less complete picture of the status of Irish hen harriers and population trends over time (see Here). What has been shown to date is that nationally the species is declining while one or two subpopulations (eg. Slieve Blooms) appear to be relatively stable over time. Some of the biggest gaps in our knowledge are where our Irish bred harriers go after they leave their natal sites, do they disperse randomly, what are the key characteristics of winter roosts and winter foraging areas, how many harriers survive over-winter and how many survive to breed themselves perhaps in their 2nd or 3rd year, where they settle and how productive they are? Do some populations function as 'source' populations for other poorer performing ones?

In 2016 we set out to begin to try and address some of these questions. Hen harriers are rare breeding birds in the Republic of Ireland requiring specific licences for ringing and tagging from the National Parks & Wildlife Service and the British Trust for Ornithology. In our first year of satellite tagging we enlisted the expert help of Stephen Murphy, Natural England. Stephen has sat tagged more hen harriers than anyone else in the world and over the years has developed and modified tagging methods best suited to ensuring tags don’t impact on the birds he is studying while giving out the data needed to follow harriers over their lifetime. Tags weigh 9.5-12g (up to 3% of body weight) and sit on the back exactly like a backpack. Preparation done beforehand means we can minimise time attaching tags at the nest site and so minimise disturbance. One chick only was tagged from each nest to minimise time and, more importantly, to spread our sample of tagged chicks across several nest sites and different regions, some inside Special Protection Areas (SPA), others outside SPAs etc.

Our first chicks were tagged in the Ballyhouras in north Cork and south-east Limerick before moving on to the Boggeraghs, Co. Cork, the Slieve Bloom Mountains in Laois/Offaly, the Mullaghareirks in east Kerry, the Knockmealdowns in north Waterford (11/7), before finishing back in the Mullaghareirks and Ballyhouras. These young harriers are now on the move and future blogs will follow these birds on their travels and, hopefully, tell us much about their lives!

This instalment was first posted on the joint project blog created by RaptorLIFE, the National Parks & Wildlife Service (NPWS) and the Irish Raptor Study Group. All three organisations are involved in the research and monitoring of Ireland’s hen harriers and the progress of these tagged hen harriers can be followed on this new blog.

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