BirdForum is the net's largest birding community dedicated to wild birds and birding, and is absolutely FREE!

Register for an account to take part in lively discussions in the forum, post your pictures in the gallery and more.

Reply to thread

Message: <blockquote data-quote="alexash" data-source="post: 1185802" data-attributes="member: 51367">Hi All, I worked for four years as a warden on The Farne Islands. Every year we got one or two Common Terns with all dark bills which otherwise appeared to be breeding adults (i.e. full black caps). There was talk at the time of them being longipennis but it was felt that it was far more likely that they were hirundo with abnormally dark bills. I do  not have the time/references to hand but I'm fairly sure that longipennis differs in other ways other than bill colour and that those birds looked like a bog-standard Common Tern in every other way-we had the luxury of studying these birds for long periods of time alongside other Common Terns.</blockquote>