Found this on the KS Listserve.
Make sure to look through those terns thoroughly in the St. L area
(HSL, Carlyle, RMBS, etc)

Charlene Malone
St. L co. 

Subject: good web article on tern ID
From: Pete Janzen <pete.janzen AT SBCGLOBAL.NET>
Date: Thu, 12 Aug 2010 00:37:37 -0500

Kansas expatriate Kenn Kaufman found an Arctic Tern in Ohio yesterday 
and posted a nice article with pictures on differentiating this species 
from Common and Forster's Terns.  Probably not bad to have this 
information in mind when looking over migrating terns in Kansas. 

Pete Janzen

The Audubon Society of Missouri's Wild Bird Discussion Forum
ASM Fall Meeting: September 24-26 at Camp Clover Point