Pacific Diver in Shetland?

Grutness, 16th May 2013

by Roger Riddington and Paul Harvey

P1060662b

A quick post from Shetland to get some feedback about an interesting diver seen earlier this evening. At about 7.30 I got a phone call from Paul Harvey, who’d just seen a stunning, summer-plumaged Black-throated-type diver in the sheltered waters of Grutness voe. Paul was out birding with bins only, was some distance from his car/scope and needed a second opinion – the fact that he couldn’t see a thigh patch on the bird made my journey time that much quicker. Shame I don’t get a company sports car from BB but there you go.

To cut a long story short, I picked up Paul, reunited him with his scope and then we started to grill the bird. The photos below tell their own story really, a bird with a solidly dark flank and an arrestingly small-looking bill. I started to try to photograph it – not so easy in low light, with the scope at x60 and the camera zoomed in to max, but at least there is something. We watched it for about 15-20 minutes, getting gradually more twitchy about it, before it (sadly) flew off strongly. In flight, there was a neat, even black rim around the flanks, with no sign of any indent towards the thigh/rump. At no stage did we see any white in the thigh either, even though the bird was typically sitting quite high in the water.

And – well there’s not much more to say. We’d be grateful of any constructive input! Pacific Diver is a major challenge in summer plumage and it would be interesting to see what people think. Seeing on average one Black-throat a year in Shetland doesn’t make us best placed to judge these things!

P1060664b

P1060690bA quick interjection from M.G. Not an easy call. Glad that RR and PVH have taken the risk of putting this bird ‘out there’. For me the photo above seems compelling. The area below the rear edge of the wing coverts is the place which is white in Black-throated Diver and dark in Pacific Diver. It appears to be dark, and this concurs with their field views. The bill looks pretty titchy too doesn’t it – and the head/bill combo feels all Pacific. They are asking the critical question in the right spirit. Hope it gets seen again- for them, and for us to learn! As already indicated, comments welcome.

P1060674b

P1060693b

9 thoughts on “Pacific Diver in Shetland?

  1. Jeff Higgott

    For what is is worth it looks good for Pacific to me! Great find and a really instructive bird!

    Reply
  2. julianhough

    Looks good, especially that spiky little bill..and if the flanks are dark as they look, then that’s the clincher. When I saw both species together in Alaska, my notes drew attention to the small bill, puffy head and a rather striking slivery bloom to the back of the nape, appearing almost whitish in some lights compared to the slightly paler gray nape in BT. Also, the neck stripes on Black-throated appeared a little bolder so the black bars were similar in thickness to the white ones. On Pacific it looked as though the neck bars were finer with the black barring being broader than the white bars…

    Reply
  3. Keith Brockie

    Are there any photos showing the side of the neck? The easiest way to separate a summer plumaged arctica from pacifica is the extent of the white neck stripes. In arctica they extend right down the neck ‘flowing’ with the belly stripes. In pacifica the neck stripes end before the base of the black throat patch, look at any photos and it can be easily seen and to my knowledge has never been commented on!

    Reply
  4. Viktor Nilsson

    A no-brainer to me, really. That thin bill, bulging neck and the flank patch are just totally typical of the many pacifica’s I’ve seen I NE Russia. I can’t really see why any better views would be needed. This is as good as it gets, and i’d be very surprised if this doesn’t get accepted based on these splendid photos!

    Reply
  5. Scott Mayson

    Pacific for me, also something I have noticed is that on Black throat the baring under the throat patch extends all the way across the upper breast/lower neck whilst on Pacific it is restricted to the sides and is finer.

    Reply
  6. Lucy

    Having lived in W Scotland and California with plenty of experience of both arctica and pacifica, it looks just like a normal pacifica to me. I can’t comment on tiny details about neck stripes, but the general “jizz” is completely pacifica and just looks wrong for arctica (mainly the shape of neck/head/bill) let alone the dark flank.

    Reply

Leave a Reply