[Birdtalk] California Gull vs Ring Billed Gull

[Lofthouse]

"Is there any reliable way to distinguish
California Gulls from Ring Billed Gulls
at a distance?"

In my opinion, no.  When you have 2000+ gulls out on the water of the Hyrum Dam at a distance of 1/4 to 1/2 mile I say, no way.  I don't care how much you paid for your scope.

I had some fun at Walmart with a bag of popcorn.  Here is some pictures.  There are birds of both species in the photos.  Have fun.

http://donce.lofthouse.com/jamaica/gull.htm

My observations:  The ring-billed is a bit smaller, and has yellow legs where the California has greenish legs.  I cannot see any difference in the shape of the bill as some have reported.   

The mantle of the ring-billed is a lighter shade of gray.  Be careful using this mark though as the lighting can play tricks on you. 

I can see no significant difference in the white spots on the primaries, nor in the amount of black.  

The California does have a dark iris, and red on the lower mandible, and red on the gape, and sometimes a little red is visible around the eye.  None of these marks can be seen at a distance.  The ring-billed has a light iris. 

Some field guides show some brown streaking on the nape of the California gull, but most of the birds in these pictures have a very white head and nape. 

Many times I enter "gull sp?".

What do you think?

Jim
  ----- Original Message ----- 
  From: birdnet at skylace.net 
  To: birdtalk at utahbirds.org 
  Sent: Saturday, April 05, 2008 11:21 AM
  Subject: [Birdtalk] California Gull vs Ring Billed Gull



  Is there any reliable way to distinguish
  California Gulls from Ring Billed Gulls
  at a distance?

  The reason I ask, is that during the winter
  I sat on the flyway where gulls were coming
  in to spend the night on a lake. About 200
  gulls came close enough for me to see the
  eyes. Every gull who's eyes I could see 
  had yellow eyes (ring-billed).  

  The next day one of my favorite posters to
  this group said that s/he had observed a flock
  of California gulls at the lake.

  So I went back to the lake and observed another
  hundred gulls at close distance, and every
  one of them had yellow eyes (ring-billed).

  I think the other poster was wrong about the
  identification even though s/he is very 
  knowledgeable about the birds of Utah.

  Beyond about 100 feet I am clueless about whether
  a gull is a California Gull or a Ring-Billed Gull,
  and if even an expert goofs I wonder if eBird might
  benefit from a California/Ring-Billed category?


  _______________________________________________
  Birdtalk mailing list
  Birdtalk at utahbirds.org
  http://utahbirds.org/mailman/listinfo/birdtalk
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://secureserver.securesites.net/pipermail/birdtalk/attachments/20080407/aad95e51/attachment.htm