Birders,
I'm quarterbacking from my couch here, but just thought I'd let folks know that the widely reported adult Common Tern at Boulder Reservoir is more likely a Forster's Tern. A few things to consider:
-The bill is how I would describe as, "honking big."
-Assessing bill color on distant terns is often futile. One person's orange is another's red. Also, it's important that bill color on these species changes through the season. They are waxing towards dark at the moment.
-Forster's Terns are white below, while Common/Arctic are gray with white chins/throats. The photos of the Boulder Res bird all show a pale white underside color.
-Flight and perched photos show the primary color being silvery gray with narrow black tips.
-On the photos available, it appears that the bird is molting its crown feathers. The shadow of the typical Forster's Tern basic plumage pattern (the dark eye mask) is apparent.
Some of the photos. The adult bird is in question:
Happy birding,
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