[Oztrich Boy]

If the intermediate populations were to die out (comet, volcano, disease, whatever), these would without doubt become considered two species. They are just NOT the same bird. It is only the existence of a continuum from point A to point B that allows these birds to be considered the same species.

Actually the two ends of the loop: The Herring Gull (Larus argentatus) and Lesser Black-backed Gull (L. fuscus), are considered to be two species, because that's how they are where their habitats overlap in the British Isles.

[ndt]

Thank you, I was too lazy to look up the name.

[b_sharp]

Just Google on 'ring species'. There are quite a few.