Caspian Tern

CASPIAN TERN, CHICAGO BOTANIC GARDEN, GLENCOE, ILLINOIS, APRIL 20, 2010

Pentax K20D
SMC Pentax-DA 55-300 at 300mm
1/500 sec. f8
ISO 100

Took a while (and the help of the Cornell Bird Lab) to identify this tern. For a while I couldn't decide whether this was an Arctic Tern, a Common Tern or a Caspian Tern. Arctics, according to the books, have a pale belly, a longish tail and an uniformly orange bill. Commons have duskier underparts, shortish tails, dark-tipped bills and dark-edged wingtips. Caspians are marked by large orange bills and large dark areas on the wingtips -- both smoking guns for this photo. It was the first time I'd seen a member of this graceful seabird family at the Botanic Garden.