While visiting Punakaiki (the Pancake Rocks between Greymouth and Westport on the South Island), we noticed that they were populated by colonies of white birds with black heads.
We were unable to get a definitive answer as to what type of birds these were.
Can anyone identify these birds for me?
Thanks.

Les, they were probably terns by the sounds of it. There are a few terns that fit that description ... Antarctic Tern, Caspian Tern, Black Fronted Tern, Eastern Little Tern and Fairy Tern.
They are all similar colouring and their distinguishing features are generally different coloured beaks and legs ... some red, orange, black or yellow .

Thanks, Christa.
I'll hunt down a picture, and see if that's what we saw.

could it have been Ibises?

PixieChick,
Thanks for the reply. These definitely were not Ibises. I've seen a lot of those, and they're pretty easily identifiable.
Christa,
After looking at pictures of Terns, that's what they appear to be. Thanks.