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From: gss@edsdrd.eds.com (Gary Schiltz)
Newsgroups: rec.birds
Subject: Forster's and Common Terns
Keywords: Differentiation, abundance
Message-ID: <114@arcturus.edsdrd.eds.com>
Date: 7 Dec 88 15:50:29 GMT
Organization: EDS Research and Development, Auburn Hills, MI  48057
Lines: 40

I've been birding now for about ten years, and have yet to identify
a Common Tern.  Most of my birding has been while I was a student at
Kansas State University in Manhattan.  With several large reservoirs
in the area, and the Cheyenne Bottoms wildlife refuge close by, I was
able to see a fairly large number of small terns, and as far as I could
tell, they were all Forester's.  At least, the people with whom I birded
all said the common small terns in the area were Forster's.  Now that I
live in the Detroit area, I again see a large number of terns and am
still unable to see any that I am sure are Common.

Does anyone on the net have any good rules of thumb for differentiating
between Forster's and Common Terns? Specifically,


  1) How can one visually tell the difference between the two?  The
     Golden field guide shows slightly darker primaries and dark outer
     edges of the tail in the Common, with lighter primaries and dark
     inner edges around the tail in the Forster's.  I've looked at
     hundreds of small terns, and even through a spotting scope, I've
     been unable to see any of these markings.  Do these markings usually
     show up well? During what seasons do the markings show up best? Do I 
     just need new binoculars (maybe Santa Claus reads this newsgroup :-)

  2) Which tern would be more abundant around midwestern lakes (i.e. in
     Kansas) and in the Great Lakes region, and in what seasons are each
     more abundant?
 
  3) Where is a good place to go to see both species in large numbers at
     the same time?
 
Thanks in advance.  You might as well post your responses rather
than email, since the birding traffic on the network has been
light, lately.
 
---
 
     /\   What cheer,  /\       | Gary Schiltz, EDS R&D, 3551 Hamlin Road |
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