Dark Gulls in Eastern Ontario last week (1 Viewer)

[Michal B]

Four of these dark gulls flew overhead at dusk on July 17, and I saw two of what I presume were the same the next day (blue sky). Unfortunately, I never did get a good photo, but they seem to be too dark to be anything that I've seen commonly. Your thoughts would be appreciated.

Cheers.

 

[Butty]

They look uniformly dark enough to be Heermann's gulls, which I think from memory does go as far north as Ontario.

 

[Michal B]

That was a thought I had, although it seems very improbable. The Heermann's Gull records in eBird show few sightings in Ontario and they were in Winter/Spring in 1999 and 2000. Are there any other possibilities?

 

[Southern Viking]

Judging by the Olsen guide, Heerman's shouldn't be showing the paler inner primary window. Why isn't it a juv American Herring Gull? Looks close enough to images in Olsen and Adriaens et al

 

[AStevenson1]

Look like very fresh recently fledged(dark) juvenile American herring gulls.

 

[Butty]

They look uniformly dark enough to be Heermann's gulls

Photo-quality is too low (no offence) for me to have relied on this (ie my error), plus... bill too big and eastern (ie well inland) Ontario puts it well out of court.

 

[Michal B]

Certainly, the Herring Gull ID would follow the aphorism "When you hear hoofbeats, think of horses not zebras." Indeed, HEGU was my first thought, but the pics seem to show a fairly uniformly dark gull, unlike the typical young Herring Gulls I've seen which show fairly distinctive patterning. I've looked online for pics of recently fledged birds, but have nor found any.

 

[lou salomon]

Certainly, the Herring Gull ID would follow the aphorism "When you hear hoofbeats, think of horses not zebras." Indeed, HEGU was my first thought, but the pics seem to show a fairly uniformly dark gull, unlike the typical young Herring Gulls I've seen which show fairly distinctive patterning. I've looked online for pics of recently fledged birds, but have nor found any.

Hi,

Gull Research Organisation

This website deals with the taxa graellsii & argenteus. Comparison of plumage month by month.

gull-research.org

You don't see the patterning due to photo quality. Heermann's is out of question, they are much lighter built. Other large gull contenders are Lesser Black-backed and Greater Black-backed Gulls, both of which are out as well on tail pattern, structure and other plumage details. So you have to choose between the relatively similar juveniles of American Herring Gull and California Gull (subsp. albertaensis), the latter breeding from Alberta to Manitoba, though, and juveniles aren't that likely to show up this early in eastern Ontario. And of course, your birds are indeed (American) Herring Gulls, which from some distance and in pics like these appear quite uniform dark when fresh juvenile. Structurally they are heavier built than California Gull, have a bit broader based wings and heavier and more blunt tipped bills. Bills don't get as fast bicoloured in A. Herring Gull as in California Gull, so that's another hint towards these being Larus smithsonianus (or still Larus argentatus according to AOU, pending a probable change in the near future).

 

[Michal B]

lou: thanks for your detailed--and definitive--response (and to the others commenting in the thread).

Cheers.