Friday 3 November 2023

First Impressions

I like to dispense with specs for seawatching. My scope eyepiece is easier to use without them, and on a rough day it's a constant battle with salt spray anyway. All good, until I need to look at my phone. And then I have to dig out my glasses from wherever they are stowed, put them on, fire up the screen, etc, etc, followed by the reverse procedure. Obviously I can't be using my phone and seawatching, so I try to spend as little time with specs on as possible. Which explains why my response to Viv's query on the WhatsApp group on Wednesday morning was rather knee-jerk.

Viv had photographed a tern at Lyme Regis and wasn't sure what it was. I took one look at what seemed to be white secondaries and replied with the word 'Arctic' and a 'thumbs up' emoji. Here's the photo...

Viv's tern  ©Viv Keene

I did register the extensively red bill, but for me the white secondaries trumped it. I put my specs away and returned to the Leach's hunt.

Yesterday morning I discovered that 'people seem to think [the tern] was a Common'. Oh pox. Like anyone else I dislike being wrong, and vowed to avoid future knee-jerk ID pronouncements. Single photos can be so misleading, and evidently I had been caught out. Like an idiot I revisited Viv's pic with that mindset and saw that yes, perhaps I'd been fooled by a photographic effect and those secondaries are actually grey, and the darker trailing edge to the underside of the primaries is broad and fuzzy rather than thin and sharp. And, of course, the bill of a juv Arctic Tern is blackish, not red. Doh!

I don't know who those 'people' were but gather there was some Twitter chat, which of course I am not party to these days. Anyway, I bowed to their expertise. And then Steve sent me a link to a video that Viv had posted there. Hmmm...

Viv kindly sent me a copy.

I clipped out a load of stills and made a collage with them...

Viv's tern (stills from video ©Viv Keene)

Many years ago I learned how to separate juvenile Common and Arctic Terns at Queen Mary Res in West London. Following a regular diet of Common Terns, my first juv Arctics were surprisingly obvious, with their white secondaries effectively a continuation of the pale primaries into a long, narrow triangle on the trailing half of the wing. This contrasting pale area is obvious in lots of those stills, and Common Tern does not have it. Viv's tern is an Arctic.

There are supporting features too. Some of the sharper underwing shots show a narrow, dark trailing edge to the primaries. The rump is white, not pale grey as in Common Tern. Also the short-necked, small-billed jizz suggests Arctic. One photo can be misleading, but 21, less so. However, there is one more to show...

Also from Viv's video, this still is from a short clip where the bird dropped briefly to the beach, allowing Viv to zoom in (©Viv Keene).

I can see where the Common Tern worries came from. Arctic Tern is supposed to have a faint carpal bar, stubby little legs...and look at that bill! Actually the legs are short if you focus just on the tarsus length. And the carpal bar probably isn't particularly dark, plus it is all exposed rather than hidden beneath scapulars. If the bird's head was relaxed and tucked in I suspect it would have a very different feel to it, and look less Common Tern-y. Anyway, whatever one thinks of the various features revealed in this perched shot, the flight shots have already nailed it. The bird is an Arctic Tern.

As Jono Lethbridge commented on a recent post, first impressions, even when brief, are often good. In this case my first impression was indeed good, but then I spoiled it by wavering too easily. I suppose the long and ever-growing list of ID errors that we all accumulate over time inevitably dents our confidence to some degree. When you know all too well how wrong you've been in the past, you also know it's only a matter of time before the next one. Which could be the very bird you're puzzling over right now!

Still, many years of experience ought really to make those first impressions increasingly reliable. I should remember that.


  1. Gav, I guess the Common Tern ID'ers were just looking at the bill and saw black on the end.

    1. I'm sure the bill colour and pattern didn't help. Not really typical of late-autumn juv Arctic.

    2. Excellent blog, Gav. Sorry that I let the nay-sayers push me into doubt. Never seen an Arctic before, so it was all up for grabs! Your instincts & knowledge are completely sound. Thank you for all of the effort. 😉

    3. Thanks Viv. Congrats on finding a new bird for yourself. I'm sure the next one won't be as controversial! 😄