Great Blue Heron with ?

[Glenn Nevill]

I photographed the nesting GBH at Stowe Lake in Golden Gate Park, San Francisco this Saturday and noticed this protuberance under the beak on one bird. I can not find any information about it, but found another reference to another bird with a similar growth on Flikr. See this page:

http://www.flickr.com/groups/csgreat...7612711987978/

So what is it?:confused:

Best Regards,
Glenn Nevill

[Jeff Wear]

http://www.birdphotographers.net/for...ad.php?t=55517
it looks like 3 now