I hope you can advise me.
I live in Cambridgeshire and feed the ducks around the marina regularly.
i have spotted an extremely strange looking bird and wonder what it could be..
It swims underwater is largish, longish, black, with a pointed face and beak that appears to have a downward tip... Whenever it is around the ducks and moorhens race out of the water onto the bank until it has gone..
i do hope you can let me know what this bird could be.
Many thanks

Sounds a lot like a cormorant to me: http://www.birdingart.com/images/gould/cormorant-w.jpg

A cormorant would defintiely be my call!

Cormorant was the first thing I thought of as well.

        I used to live and bird in Cambridge and there are lots of cormorants in and around the Cam and the gravel pits to the north and south.

"Hope is a duty from which palaeontologists are exempt."
David Quammen