David Pedder said:
I am a relatively new birder. I spent several fascinated hours on Sunday watching what I believe were Common Terns performing aerial acrobatics over a lake at Little Paxton Pits, Cambridge. I have never seen them before and was quite mesmerized by their flying skills. They were like large, white swallows! What confused me was that several of the Terns in the group appeared smaller than the rest. Might these have been juveniles or might they have been Arctic Terns? Do you get mixed groups? (Tail streamers were short).
Hi David,
Whilst being no sort of Tern expert, the subject has been exercising my mind a bit in recent weeks (see
http://www.birdforum.net/showthread.php?t=36972)
Without going into all sorts of exotic species that are unlikely to be seen, here's my beginner's take on Tern ids!!
Big Terns - Likely to be Sandwich Terns.... identified by black legs, black bill with yellow tip and shaggy hair-do
Middle-sized Terns - Could be Common (Red legs, reddish bill with black tip (variable!!)), Arctic (Red legs, reddish bill with no black tip (usually!!)) or Roseate (Black bill, red legs)
Small Terns - Little Tern (yellow/orange legs, yellow bill with black tip, white forehead) or Black (errr.. if not black, then certainly dark at this time of year, black bill)
In addition to these physical differences, there are also some good id pointers to be gained by watching them fly and fish - many doing this in quite different and distinctive ways. Once you get your eye in, you may well find that you can separate some species quite easily by flight and wing pattern.
Juveniles is another story altogether - suggest Field Guide for that one!!
Here's a picture of an adult Common Tern and a fairly well-grown juvenile, which may be of some interest....
Hope this helps..... Ruby
