Acciedental capture: silhouetted birds receding into a contrajour scenic

This is a bit of a half-hearted hope, given that the birds in question are not really the subject of the picture, but a tiny part of a big landscape. However, maybe some genius can shed some light.

I was in Berwick on Friday, walking around Pier Road. Apart from a very confiding wheatear, I didn't get much in the way of meaningful wildlife photos, because I was wandering around with a 24-70 lens on my camera. 

However, when I got to editing this landscape shot, looking across the estuary toward Tweedmouth, I realised that I'd caught a very distant squadron of pterodactyls flying just below the cloudline of the main bank of cumulus, about a third of the way in from the left edge.

Can anyone say what they actually are?