Saturday afternoon, 4 Oct 2015, Dave Bray and I watched at least 6 different 
terns at the north end of Boyd Lake. They were seen sitting and flying through 
telescopes, but always quite distant. At least two were Forster's, with black 
patch on face, and dusky gray on hindcrown and nape. At least 4 were apparently 
Common Terns, one of which was a full gray-bellied, black-capped adult. The 
other 3 were young birds with white fore-crowns, There may have been a fifth 
bird, an adult starting to lose its gray belly and black fore-crown. 
Low-quality digiscoped images support the identification of Common Tern, 
although all of these showed various features of Arctic at one point or 
another, causing much confusion in the field. For example, they all had pale 
bills. The bill of the adult lacked a black tip. In some views, bills looked 
short. Legs were shorter than the legs of the Forster's Terns with them, 
causing them (but not the Forster's) to waddle when they walked. One of the 
young birds appeared to have a tail that extended longer than the wingtips. The 
young birds had frosty wingtips and barely visible carpal bars. Nonetheless, I 
am pretty sure that they were all the same species, and photos indicated 
longish legs when standing, and long neck in flight. Better photos might prove 
me wrong about the identification, so I encourage other observers to document 
these birds, which are rare in Larimer County. Its been a great year for terns 
at Boyd Lake State Park. I wonder if these could be the same pod of terns that 
were there 3 weeks ago. That pod included one well-documented Arctic. I would 
search for these roosting at the Swim Beach or roosting in the northwest corner 
(among duck-hunters). Lots of Franklin's, California and Ring-billed Gulls were 
also present, as well as two Sabine's Gulls floating just north of the Marina, 
and my FOS Herring Gull (an adult) at the Swim Beach. 
  
Just west of Boyd, at Horseshoe Lake, the resting gull flock harbored 4 Lesser 
Black-backed Gulls (3 adults and 1 2nd-cycle immature) in the northwest corner. 
A digiscoped photo of these can be viewed at 
http://www.pbase.com/quetzal/image/157696530 . They are hard to pick out among 
the densely packed California Gulls. 
  
Nick Komar 
Fort Collins 

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