Wednesday, 23 October 2013

More harrier stuff

The bird is still present this afternoon and has now been twitched by some local observers. Has caused a bit of a stir alright, not much time for musings from me here except to add a little more to the debate, including more third party comments I have received. Of course I myself am a little biased...Little negative feedback has yet appeared (apart from rumours some still doubt the i/d) but no response yet received from Dick Forsman on the prospect of hybrids.

Some new photos by Garth Peacock here

Many seem troubled by the strange upsurge in records from Tacumshin (6 birds in the last 3 years) and are wondering if Northerns could be interbreeding over here. It should be borne in mind Tacumshin is a mecca for transatlantic vagrants (often hosting several species at once, sometimes in numbers, such as the recent flocks of 26 buff-breasted sandpipers) and it should be remembered that all six harriers were found in October, the main month for yank vagrants. Is this not in itself a coincidence? Personally, I think it points to transatlantic vagrancy, in the same way two Eastern kingbirds have turned up out of the blue two years running on islands off the Galway coast. Maybe we'll get another next year?! And we do see changing patterns of occurrence with vagrants expanding ranges and shifting migration routes - RF bluetails increasing (from mega status to imminent 'relegation'), more yellow-broweds and Pallas's, herons slowly colonising from the continent, brown shrikes turning up increasingly frequently. I wonder what's happening with hudsonius in the US? The recent Northern harriers in UK & Eire have all looked the part whereas dodgy cyaneus have been around for a long time. For now we can look forward to DNA analysis of the current Tacumshin bird and the rumoured prospect of an imminent split. Gripping stuff! Watch this space...

from Martin Garner:

My gut reaction was that your bird looks remarkably good in overall appearance for hudsonius. More strikingly so in regard to head pattern, underparts colouration and lack of streaking and upperparts, than some others in W Europe in recent years which are also fine for hudsonius. I then went through the wing tip barring minutiae and came to the same overall conclusions as Killian, – I was (pro-hudonius) animated by 4 bars on p10 and fine for hudsonius on p9 and p8. I did wonder about  p7 and p6 on which there only appear to be 4 bars, as I thought there were usually more on hudsonius- but that is in part my ignorance and I need to look into that feature more.

More importantly for me the overall appearance is outside of that I would expect for cyaneus and so strikingly hudsonius –like, that I would rather explore the road of greater intraspecific variability in hudsonius than out it down as odd cyaneus. Repeatedly, understandably narrow criteria that have been laid down for ID purposes, subsequently get widened as we have discover more about the variation in closely related/ close-in-appearance taxa. So I think your bird looks like a Northern Harrier (I do like old ‘Marsh Hawk’) much more so than a European Hen Harrier. There will still be questions and learning, but I am envious of your find.

And from Brian Sullivan, author of several raptor I/D papers in North America:

Looks fine for Northern Harrier to me. Dark eye = female. Wing panels are the result of over-contrasted image in PS, but otherwise this bird looks typical to me.

No comments:

Post a Comment