Sandwich Terns at Bettyhill

[Rheghead]

There were some sandwich terns flying around the beach this afternoon. I didn't see the yellow tip to the black bills or the black crests as they were always in flight so I will refrain from saying they were gull-billed terns though I thought the wings had dark trailing edges but the bills were long and thin like a sandwich tern.

I need a second opinion really.

[Pterodroma]

Hi Rheghead

I am confident that what you saw were Sandwich Terns. Gull-billed is rare in the UK occurring mainly in the southern counties of England. I am not aware of any records for Sutherland or Caithness.

In flight Gull-billed has a grey rump and tail whereas in Sandwich they are white (although there are rare birds that have a pale grey rump but never as dark as Gull-billed). The bill of Gull-billed (as the name suggests) is stout and heavy with a pronounced gonydeal angle, the bill of Sandwich is long and slender with no marked gonydeal angle. The yellow tip of Sandwich is not always noticeable in flight, neither is the crest.

Gull-billed looks more chunky than Sandwich and its flight action is more gull like and not as bouyant as Sandwich.

Field guides usually show Sandwich with darker outer primaries contrasting with paler grey inner primaries. However, this pattern becomes more pronounced as the summer progresses and the feathers become warn. At this time of the year, soon after the partial moult into summer plumage, the contrast is less marked.

One important distinction is feeding action, Gull-billed does not plunge dive, but rather picks at the surface in the manner of a Black Tern

I hope that is of help.

[Rheghead]

Thanks for that, very interesting. They were diving like sandwich terns do.