Tuesday, 3 September 2013

Sabine's Gull among Kittiwakes

Sabine's Gull is a rare in Atlantic Canada.  Migration routes take eastern Canadian Arctic breeders to the European/African side of the ocean during spring and autumn migration. A few individuals splinter off from this route and show up in the offshore Newfoundland.  But Sabine's Gull from land is a significant rarity in Newfoundland. In nearly 4 decades of birding in Newfoundland I've seen Sabine's Gull only twice from land.  1) L'Anse-aux-Meadows 10 Aug 1991 and 2) Cape Race and the next day off Daley's Cove in late August 2010. Both were adults in breeding plumage.
 
 
Currently I am on a seismic vessel working in the northern Labrador Sea near the pathway for birds leaving the Canadian Arctic. But even here they are few and far between with only a handful during days of extensive looking.  I was lucky enough to get photos an a juvenile near the boat with kittiwakes (abundant here).
 
 
Sabine's Gulls are a unique and beautiful gull. They are unmistakable at close range but at long range the juv Black-legged Kittiwake can look deceivingly like a Sabine's Gull.  The problem comes when people do not realize just how white the triangle on the inner wing of the juvenile kittiwakes looks at a distance.  The confusion starts with the field guides that typically show this area as gray, similar to the rest of the upper wing and back. This is not wrong. At close range this is more or less how it is.  But at long range things are different and this triangle appears noticeably whiter than the rest of the wing and upper parts of the kittiwake.  In overcast skies the white triangle contrast is more dramatic.
 
 
Even myself with considerable seabird experience is often working on the identification of a long range juv kittiwake.  I see the white triangle and ponder the bird. I wait until I detect the colour of the back as being pale gray or see the diagonal black wing bar, then I know it is a kittiwake. Many times the bird is too far away to determine this so I assume it was a kittiwake.  I would never label a bird as a Sabine's by elimination, i.e. the back not looking pale gray or not seeing the black bar.  You need something solid before you ID a Sabine's in Newfoundland.  BTW adult Sabine`s have gray back too but a shade and a half darker than kittiwake.
 
Adult Sabine's Gulls are pretty well always going to have a dark hood while within our borders. They wait until arriving on their southern wintering grounds to moult to winter plumage.  Occasionally a 1st summer bird is seen in Newfoundland waters during the summer. These look like adults with a mostly gray head but seem to loose it early, so adult-like birds without a gray hood are possible from mid summer onward. (one off Cape Pine by Cliff Doran in July2013).
 
Below are photos of juvenile Sabine`s Gull in the north Labrador Sea on 31 August 2013.
 
A juvenile Sabine`s Gull on the north Labrador Sea on 31 August 2013.  Note the small size compared to the kittiwakes. It is actually only the size of a Bonaparte`s Gull but the size difference becomes less apparent in flight and exposing that big wing pattern.
 

The fully spread wing revealing the patented Sabine`s Gull pattern.
 
Juvenile Sabine`s  Gull and juv Black-legged Kittiwake.  Difficult to imagine how the two could look the same even at long range.  On the kittiwake you can see the whiter tinged feathers on the inner triangle. That black bar serves to enhance the division of the whitish to very white looking triangle from the rest of the wing.  The black bar seems to vanish on long distant birds but when you can see it you know it is a kittiwake.

A field guide style posed photo showing the juv Sabine`s and a juv and adult kittiwake. A genuine Sabine`s Gull is a genuine thrill in Newfoundland and Labrador.
 

2 comments:

  1. So winter adult Kittiwakes get a blark mark dash on the sides of their face in winter plumage because they have no such marking with summer mature kittiwakes yes or no?

    ReplyDelete
  2. Great blog entry. Thank you for all you do.

    ReplyDelete