White-billed Diver – 2011

Gavia adamsiiTrochydd PigwenVagrant

Seawatching at Strumble Head on the 1st September 2011 (where the lookout faces north so there is rarely any sun glare to deal with and colours are clear and accurate) it had been quite a good day considering the wind direction.  I had been in the lookout since 6am (as with the previous 5 days).  The SE wind produced (as predicted) a strong passage of Comic Terns with a few Skuas mixed in.  There were large numbers of Kittiwakes in the bay and there had been a reasonably large passage of Common Scoters, including the autumn’s first Wigeon from the lookout.  Surprisingly there had been a couple of Sooty Shearwaters seen late morning.

Shortly after lunch the passage of terns was starting to slow down a little with loose feeding flocks dotted around the bay.  A number of “holidaying” birdwatchers had come and gone since late morning and I was once again on my own.

At around 1310 hr I glanced across to my left towards the lighthouse, bearing of 0915, (a clock system is used to give bearings with “12 o’clock” being due north) and spotted straight away a diver flying (with naked eye—demonstrating how close it was) that must have come from just around the lighthouse island.

I quickly ‘scoped the bird, bearing of 0930, and at a range of circa 300yds (this was its closest).  I then followed the bird as it roughly followed the tide race in a NE direction.  At a bearing of 1200 (i.e. straight out) it was at a range of circa 1/2 mile to 3/4 mile.  It continued on its NE path until a bearing of 1400 when it turned slightly and appeared to head due north.  I followed it until it was at least 2 miles away and heading due north.

In all I watched it for circa 1 minute. All of the required plumage features were logged from the first sighting, and all were seen very well.  The bird, at all times had the sea as a backdrop due to its low level flight so was never silhouetted against the sky. 

The key identification features noted were as follows:

Very large diver.  Obviously larger and more bulky than Red and Black – throated.  Neck thick along length and wings relatively broad compared to Red and Black – throated.

Noticeably slow wing beats—much slower than Red and Black and appeared to be slower than Great Northern.  This added to its large size impression.

Very big feet protruding well beyond tail.

Very large, yellow coloured bill that was noticeably up-curved on the lower mandible making the whole bill look slightly up-curved.  I am aware that occasionally some Great Northern can look pale billed due to their silver grey base to the bill but this was obviously yellow and not silver and was yellow for complete bill—base to tip.

White face with dark eye clearly visible against white.  On Great Northern the eye is always enclosed in a dark face.

Pale sides of neck along length of neck.  Lack of contrast between darker upper side of neck and pale below.

All three above points made the bird look very pale at the front—neck, face and bill.  These features remaining clearly visible especially the bill colour even at long range.

Overall colouration of the back and upper wings a lightish grey brown.  (Compared to the darker uppers of Great Northern—even in juvenile plumage).  This feature also was very noticeable even at long range.

No white spotting seen on upper parts.  Upper wing and body appeared to be fairly uniform in colour—i.e. lightish grey brown but this may have been due to the range.

I have no doubt about its identity.  Some post sighting research shows that one was seen from here by fellow seawatchers on 27 Sept 1999 although that bird was a transitional plumage adult.

Richard Stonier

More about the White-billed Diver in Pembrokeshire