tern id....thoughts please (1 Viewer)

I was looking through some of the older threads and was looking at one posted originally by Marylan about identification of Forster's Tern. Several replies noted how many may get over looked in the summer in the UK. Which prompted me to go back to some photos I took during the summer while tern wardening on the Isles of Scilly in 2003.

I thought at the time that it might have been a Forster's but didnt get enough on it (ie never saw the legs, or tail properly) to make an identification at the time, but thought it odd enough to get a couple of pics. Having showed a few other birders the pics I put it down to just an odd common tern....but something still bothers me about the pictures, mostly the cap pattern. Having watched terns all summer I never noted a common having such a wavey lower edge to the cap no matter how they were sat, and having done an internet search of pics found some shots of Forster's tern in the US showing very similar head patterns.

The following links take you to the pics

www.utahbirds.org/birdsofutah/BirdsD-K/ForstersTern.htm
www.monroe.k12.il.us/websites/dkassebaum/terns.htm
www.mangoverde.com/birdsound/picspages/pics68-18-thmb.html
and best of all
www.mbr-pwrc.usgs.gov/id/famlst/io690id.html which shows an adult summer (alternative) in fresh plumage

Is head pattern enough to ID an adult summer forsters alone? The primaries on this bird were not especially pale, concolorous with the rest of flight feathers, and with a strong black vein to the outer primary which you can make out in the second pic

Thoughts welcomed, just wish I had seen the bird again.

Cheers

ben

My initial thoughts were Common rather than Forster's;the bill doesn't look long enough and is red rather than orangey red.I'll have another look later,by which time our experts will probably have contributed.

Heaven knows I'm no expert on Terns - or, rather, I'm even more inexpert than on other things - but, checking the pics I have, it seems that in any plumage other than adult summer, Common Tern (and not only them) usually have an area of black behind the eye that projects well below the eye. In other words, although there is overall less black on the head the bit behind the eye projects lower than in an adult summer bird. Thus I wouldn't have thought it would take much of an abberation for an adult summer bird to show the head pattern that yours does.

Also, since silvery primaries are supposed to be a feature of adult summer Forster's and show up as reasonably concolorous with the mantle on most (though not all) the pics I've seen, I wonder whether the primaries on your bird are a bit too dark?

All of which suggests Common to me - but don't rely my opinion!

Jason

Seeing as this is your first post PinkPigeon, I did want to extend a warm welcome to you from the staff at Bird Forum.

I will leave the I.D.ing up to the members more familiar with the terns in your part of the world but again welcome.

www.mangoverde.com/birdsound/picspages/pics68-18-thmb.html
and best of all
www.mbr-pwrc.usgs.gov/id/famlst/io690id.html which shows an adult summer (alternative) in fresh plumage


I couldn't get these last two URLs to load (that infamous 404 msg).

Don't know if this helps any, but here two different Forster's terns taken on the same day on very nearly the same rock in a Los Angeles tidal creek. Sorry, wish I'd recorded the month on the slide. Also apologies for the softness of the shots -- the slides are sharp but my scanner isn't.

Wow replies so quick! fantastic.

Thanks for the welcome KCFoggin. Is that an American flag I spy at the bottom of your reply? No id tips on Forster's from the US?

Some books seem to depict forsters having a wavey base to the cap, while others do not. The only ones that do show it eg terns of europe and north america and the attached website link suggest freshly moulted birds? My bird was early July I think....I'll check the date.

Ive never seen a Forsters so can only go on the books.

Thanks for all comments so far....guess just a common after all ;(

sorry the links for the pics again

http://www.mangoverde.com/birdsound/index.html
then click terns and forsters tern, several images here show wavey cap

and
http://www.mbr-pwrc.usgs.gov/id/framlst/i0690id.html

cheers

I would think, if this were a Forster's and it was the time of year that it had a completely black cap, the primaries would be noticably paler than the rest of it, not darker as this appears to be. Forster's do seem to have wavey bottoms to the cap - but several others do too. I'd say bill color for yours looks like Common, and bill size is hard to gauge, but I'm thinking it's a bit small. I'm leaning towards Common overall. As others, I'm no expert - it's been awhile since I've gotten up-close looks at the 2 spp. My suggestion - go back there as they transition to nonbreeding plumage - I can ID Forster's then!

it does look very much like a Forsters and could cause a bit of excitement, however, the bill is not thick enough by quite a way

Thanks for more replies. Seems everyone is leaning towards Common, does anyone have any pictures of Common's with similar cap shapes that I could see?

Tim, you say it does look like a Forster's, but bill is not thick enough....does that mean you lean towards Common as well?

I was wondering if there had been any records of Common and Forster's forming breeding pairs in UK or elsewhere, and what characteristics they might show. There was a lone Arctic that tried desperately to form a mixed species pair at the same site, though unsuccessfully.

Thanks all.