Yesterday I checked Hvannasund: 46 Iceland Gulls including 9 Kumlien’s Gull. I also checked Klaksvík, where there were about 100 Iceland Gulls and 5 Kumlien’s Gulls. I even managed to get a photo of a 1. winter, 2. winter and a 3.winter Kumlien’s Gull together. Times are in deed exceptional at the moment.
In the afternoon Rockmund called me. He had found a putative adult Thayer’s Gull in Runavík. It was already dark, so I couldn’t twitch it.
This morning our oldest daughter and I went to Runavík in order to connect with the bird. When we came to Runavík the harbour was almost empty – 9 Iceland Gulls and a few Glaucous Gulls – yes, that is an empty harbour these days!
But then I felt the force – the advise of the jedi-birders of Shetland: Use bread! (Ok, I’m currently watching “The Empire Strikes Back”). I had brought some bread with me and as soon as I threw it out the gulls came. And it didn’t take more then 5 minutes before a truly stunning “white-winged gull”-type with black markings on the primaries appeared as the sun broke through the clouds.
It gave really good views as it was standing with some other gulls, but I never got really good flight shots. As soon as the bread was eaten the gulls disappeared. During the weekends there’s no food for the gulls at the fish factories so they tend to disperse.
I went to the local bakery and got my self a sack of bread – if the dark gull was an american it would be attracted to this much food. So I started throwing out bread. But soon it became evident that it was a wee bit overkill. It was easy enough to locate the bird when there were 50 gulls in the harbour, but soon there were about 300 Herring Gulls and 80 Iceland Gulls feasting on the bread.
I found four different adult Kumlien’s Gulls but the dark bird was nowhere to be found. I don’t think that it just blended in with all the Herring, Iceland, Kumlien’s, Common and Greater Black-backed Gulls. It was probably disturbed by all the activity and had gone.
But I stayed in the harbour for another two hours watching all the gulls feasting on the bread. Then I went to Toftavatn – 11 Iceland Gulls, several Herring Gulls and the dark gull were roosting there. At Toftavatn the birds are quite far off and pretty soon after arrival the bird took of. I checked the harbour once more, but I couldn’t relocate the bird. On the way home I checked Leirvík where 14 Iceland Gulls were present, but no Kumlien’s Gulls.
Normally the challenge is to distinguish between pale Kumlien’s Gulls and dark Iceland Gulls. Todays bird provides us with the challenge to distinguish between a dark Kumlien’s Gull and a Thayer’s Gull. I’ve never seen an accepted Thayer’s Gull before, so I have no experience with the species. So you are most welcome to comment on this bird – but I’ll give a few comments under the pics.
As mentioned I’m no expert on Thayer’s vs dark Kumlien’s Gull. But according to Gulls of Europe, Asia and North America (Olsen and Larsson 2003) this is not a classic Thayer’s Gull.
The mantle colour should be darker.
The iris should be darker (10% do show pale iris).
The dark markings on p9 should be more extensive.
P10 should show dark tip (but I kind of feel that this is like looking for the pale egde on a Palla’s Gropper or the primary projection on a Pechora Pipit – it is almost impossible to see in the field).
Most often Thayer’s Gull has dark markings on p5.
If the above mentioned things were spot on we would have a classic Thayer’s Gull. The question now remains. Is this a Thayer’s Gull in the pale end of the scale or is it a Kumlien’s Gull in the dark end of the scale?
And could a non-classic bird ever be excepted anyway?