Pure birds, intergrades (and they all look pretty smart anyhow!)
by Martin G. with photos by Lee Dingain (Almost Birding)
I was birding with Mark Thomas, on his ‘patch’ at Buckton, East Yorkshire on the morning many were at, or heading to Margate, Kent to see the reported Dusky Thrush. We had seen early photos of the bird and were interested in the bird’s appearance. Up came the subject of a 2nd cal year female Black-throated Thrush which Mark had found, at Buckton (what a patch!) in March 2007. That bird, which I saw very well but failed to photo as well (see here!) had an unusually striking pale supercilium (for a Black-throated). Mark mention than it had been suggested to him that his bird was not ‘pure’. We talked about how, in profile at least, the Margate bird didn’t look that different to the Buckton Black-throated. Ruminations.
Lots of new pics of the Margate bird soon appeared:
But the concerns didn’t go away with them. There were clearly some dull reddish tones on the breast sides and the flanks had a peculiar Black-throated feel, as already discussed. And where were the dark feathers centres to the upperparts expected in an ‘easy Dusky’? These were just ruminations. I simple don’t know enough about variation in 2cy Duskies to make definitive statement.- so tweeted the key question on my mind- “was it pure?”. It wasn’t the most popular ‘tweet’ I have ever posted : ). I certainly wasn’t the only one with questions however and Alan Tilmouth and Terry Townshend were very helpful with news and views.
Thoughts from Asia
So I’ve said my bit. Would like to know the variation in appearance of young 2cy female Dusky Thrushes from the ‘core range’. Meanwhile a few thoughts from a few who know a lot more than me, (and they are very cool birds anyway!). Special thanks to Terry T.
As you probably know, we seldom get to see many Duskys here as late as Mid-May, so I have much less experience of them so late in spring than eg between Oct-April. Naumann’s and intergrades too have gone though by late April. The Surfbirds thrush looks odder in some images than in others. You might be right, but I am not so sure of structure – seems to be fair amount of variation in Dusky etc I think the pallor of the bird on the upperparts too is okay for Dusky at this time of year – and it does show some darker markings eg on the scaps (as in 2 of the Duskys here this past week). The only obviously odd features for me appear to be (1) the warmth of the markings on the breast sides and (2) the streaky look to the lower flanks. Some Duskys do show such warmth on the breast sides (chestnutty, not rufous), as do most (all?) hybrids with Naumann’s (so this could be a 2nd generation hybrid or..?). Streakiness of markings on the lower flanks is much less usual, and as you know this latter feature might well hint at some possible hybrid influence from one of the “dark-throated” thrushes.
So – either a very odd 2cy Dusky or a slightly odd 2cy “Dusky plus [intergrade]”.
Very best wishes to you and yours,
Nial Moores (Birds Korea)
Thanks especially to Lee Dingain of Almost Birding for use if his wonderful images of the Margate Thrush
More fine images on Josh Jones’ Blog