White-billed divers off Portsoy

Here is a selection of my best photos of what I think were seven different white-billed divers we saw off Portsoy on 21st April.

Thirteen of us were lucky enough to be on board the MV Gemini Explorer, which set out from Buckie on 21st to see if it was possible to find white-billed divers at sea off Portsoy in Aberdeenshire, and try to get an idea of how many were there.

We encountered our birds approximately 2 - 2.5 miles offshore between Sandend and Portsoy.

The first two photos are of the first bird we encountered Wbd01 and for some reason, presented us with more challenges than all of the others, mainly because we struggled to get close to it at first. As soon as we could see it more clearly, it turned into a classic white-billed diver in transition plumage. On first sighting, we could see a very grey back of the neck which contrasted with the developing summer plumage on the crown, face and throat. At distance, the bill was not visible, c.f. great northern diver which were showing all-black bills that stood out against the background of the sea. The contrast between the head and hind-neck is interesting and not so clear as on great northern, which has much sharper contrast between the rear and fore-neck than white-billed diver in winter plumage.

WbD01

As we got closer to WbD01, the shape of the bill and forehead became clearer. Note how the top of the bill (culmen) is flat and only slightly inclined upwards relative to the sea surface. The lower mandibible has a pronounced gonys which gives a sharp angular shape to the lower mandible and the marked up-tilt to the outer 2/3 of the bill. Great northern shows more symmetry between the lower and upper mandible, with a much more gentle curve to both mandibles.

Note that although the base of the bill is dark (c.f. great northern) the outer half is clearly very pale, and has the distinctive ivory or yellowish tone. Pale-billed great northern divers will show at least some dark pigment along the top of the upper mandible, especially at the tip. Note also the pronounced bump on the forehead, which is generally steeper than on great northern.

WbD01

We spent quite a bit of time with Wbd02. Because the photos are better, it is much easier to see the features I highlighted for WbD01, from which it differs in having less dark pigment on the bill and has very little dark feathering from summer plumage on the head. It has acquired most of the black feathering in the wing coverts, so clearly this area appears to moult much quicker than the head and neck feathers. If the wing coverts moult at the same time as the flight feathers, does this mean that they should have completed their flightless phase by this stage in April too? This individual was recognisable from the photos because in some shots there is a loose covert (median covert) that sometimes sticks up.

WbD02

Note the plumage around the head which shows how pale the normal winter plumage is around the eye and the eye and hind-neck. Great northerns show much stronger contrast in winter plumage between the hind-neck and fore-neck. There is also a clearer distinction between the crown and the lower face and throat, with any pale areas around the eye being much narrower than on this bird.

WbD02

This photo shows what I call 'Joker-face' (with apologies to Lady Gaga and Jack Nicholson). The strong dark line on the gape. This doesn't appear to be anywhere near as pronounced on an great northerns I have seen or in any photos on the web. It is also accentuated by the dark base of the bill which also doesn't appear to feature to the same extent in great northerns.

WbD02

Note the sticking up covert in this photo

WbD02

WbD02

WbD02

WbD02

WbD02

WbD02

I took these next two photos after the photo of WbD03. I thought this was a different individual again when on the boat, but on looking through these photos, the identical plumage pattern on the back of the head and evidence of a 'lifting' scapular satisfies me that this is the same as WbD02

WbD02

WbD02

This blurred shot is what I am calling WbD03. It suddenly popped up next to the boat while we were trying to photograph WbD02 and I struggled to get an in-focus shot of it. Apart from both WbD02 and WbD03 being visible at the same time, my rather poor shot of WbD03 seems to show that it has more black around the crown and lower ear coverts, and if representative of both sides, the bill appears to have more dark at the base than WbD02. 

It appears similar to WbD04 (below) but appears to have less black around the throat and more black on the back of the head. We had also moved a considerable distance in time and space before we found WbD04.

WbD03

This is what I am calling WbD04 and is the only photo worth including of this bird. It has a medium amount of summer plumage around the head. This individual is perhaps most similar to WbD01, but has much patchier summer plumage around the throat, hind neck and forehead.

WbD04

These two birds stayed together for the whole time we were with them and were least advanced in their moult stage. They appear to have moulted most of their wing coverts but have almost completely winter-plumaged head and neck.

WbD05 & WbD06

Note the 'Joker-face' is present on these birds, even though the moult has barely begun around the head.

WbD05 & WbD06

This was the most advanced towards summer plumage of any bird I photographed. I suspect there were two birds we saw in similar stage. Note that there remain a few white feathers on the crown, throat and neck. Note also that the bill is still quite dirty around the base. Photos of this species on their breeding grounds should pure yellow/ivory bills.

WbD07

WbD07

WbD07

Finally, special thanks to Paul Baxter for having the gumption to organise this trip and for advice on where best to go - it's a shame he couldn't be on this first trip. 

Thanks also to Davie and Iris on Gemini Explorer for skippering the boat and looking after us. Davie's sharp eyesight and boatmanship helped smooth the approach to these birds to allow us to get photos. 

Thanks also to my companions on the boat for their good company, interesting discussion and their sturdy sea legs.