Sunday, September 22, 2013

Hen Harrier Roost Surveys.

Within last week I've spent three occasions looking at sites that I feel, based on past experience, might be used as roost sites by hen harriers in winter on Islay.  I'd like to try and extend the work to Jura too , but that's another story.  Next month ( October ) the monthly counts begin in what will be the  31st season of the survey. Last winter I spent a whole series of late afternoons watching out for birds moving to roost at new sites, but without success ( so much for past experience!! ). There is a small roost on the RSPB Gruinart Reserve, which is monitored by the permanent staff, but any others on the island are largely an unknown quantity in all respects!!  I did come away with the conclusion that there appeared to be fewer harriers around in toto on Islay than I was used to seeing in the past and I also now feel the same about the current breeding population on Islay too.. The deliberate targeting of the species by certain factions of the shooting community in past winters at roosts on the mainland has diminished noticeably the overall numbers around in my opinion. No breeding pairs are now present in England and I suspect the Scottish population has been similarly reduced .

 I sometimes smile when I hear people say, here on Islay and outside of the breeding season , that they've had  six or eight harriers in the day. That's entirely possible, of course, but there's also a need for caution as harriers can cover a heck of a lot of ground during a single day as sat tagged birds have demonstrated.  That's one of the reasons why counts at roosts are held, not just to try and count the numbers but to avoid the possibility of duplication.

For England and Wales the survey is organized by the British Trust for Ornithology and Hawk and Owl Trust in partnership and, for Scotland, it's organized by the RSPB ( see contact details below ). By preference , the counts are held on the third Sunday in the month for the months of October through to March and all the necessary instructions can be obtained from the above contacts dependent on where you live. It's also important to submit Nil Returns. For obvious reasons the information is treated with strict confidentiality and should be treated as such by observers too.

From past experience in the Forest of Bowland , Lancashire I can admit to having spent many happy weekends involved in the above work along with colleagues Bill Hesketh, Bill Murphy and various contract wardens.  We proved that birds were sometimes returning to the high fells to roost, most often singly but not always, and were using isolated  juncus beds, even in excess of a 1000 feet. This was all new at the time, as was the fact that they didn't necessarily return to the same roost on consecutive days. Weather played a part too and roosts could be adopted or abandoned at will. An examination of a site during daylight would reveal a small platform of stems bent over to provide a flat surface on which the bird could rest. Sometimes the sites would be quite wet, a feature which didn't appear to put the birds off.  I often thought that being at altitude in a "Bowland winter" would be seriously challenging until I lay down one day in a  juncus bed ( a dry one! )  and realised that  the roosting  "chamber" was out of the wind, relatively cosy and that any disturbance could easily be detected.  Of course, all this chopping and changing meant that results were variable, inaccurate and could only be used to construct estimates, but the data had its uses nonetheless. Roosts at lower altitudes in the wider Bowland area never held more than two or three birds , if that, so there appeared to be no distinct preference for high or low sites even in the worst weather.  Good times!   Now, sadly, a thing of the past until such time as the current atmosphere of deliberate persecution is brought to heel and the population improves. Given that "the Bills" still visit Bowland at least twice a week, and have done for many years, it was infinitely sad to hear Bill Hesketh say a little time ago that it was several months since he'd seen a harrier in Bowland. A stark contrast to the halcyon days of the 70's when there was in excess of forty breeding pairs and where, as young men, they did so much sterling monitoring work.

It's recommended that the observations are carried out previous to dusk, although they can be conducted in the morning. I've never personally favoured the latter as birds seem to slip off in the early light and are difficult to detect.  Having said that I can also remember returning home from a roost watch in the Peak Park some years ago and having a male Hen Harrier speed through the car's headlights in the otherwise utter darkness!

Current circumstances dictate that we gather as much data as possible on this species and, therefore, if you have an opportunity to assist, please contact one of the organizers below dependant on where you're located.  Many thanks.

England and Wales   Anne Cotton (BTO )  e-mail    anne.cotton@bto.org

Scotland                   Chris Rollie (RSPB ) e-mail     Chris.Rollie@rspb.org.uk

I've identified six areas to investigate this winter so I hope past experience provides a better steer in the coming months than in 2012-13!!