Image: Joseph Kennedy, 16 August 2008 [larger view].
Nikon D200, Kowa 883 telescope TSN-PZ camera eyepiece 1/750s f/8.0 at 1000.0mm iso400.
Rick Wright, Managing Director of WINGS Birding Tours Worldwide, writes:
Another teeny tern. If that wasn’t your first thought, you might want to run back through the other tern images in this series and try to get a sense of what a big tern looks like, a medium tern, a small tern; you’ll soon find that very subtle proportions and relations within the bird itself, even absent any external basis for comparison, can help you sort them into rough size categories.
At the first level, this is an easy identification. Measured against the grains of sand, this is a very small bird, and the only very small tern in North America is the well- and aptly named Least Tern. The bill and legs of this individual are still yellow — unique among North American terns — and the white forehead is crisply set off from the rapidly molting black cap. The standard identification character for this bird in flight, the contrasty wing pattern, is also visible with the wings folded: note how the outermost primaries (the lowest long feathers in the folded wing) are jet black, while the others are gray. Spread this wing mentally, and you get the abrupt black leading edge of Least Tern’s wing (and you probably won’t be able to help hearing in your mind’s ear the distinctive little squeaky chatter of this bantam sternine).
A fly in the tern ointment? Of course. A straightforward picture-match in the North American field guides turns into a bit of a nightmare when we bring Little, Saunders’s, Yellow-billed, and Peruvian Terns into the mix. This isn’t a gratuitous wrench in the tern works, either — a couple of members of the group have strayed incredible distances (Large-billed from South America to Wisconsin, Whiskered from central Europe to New Jersey), and it’s probably not safe to put anything beyond these long-winged ocean wanderers. The challenge is acute in Hawaii, where both Little and Least Terns occur at nearly the same frequency, and any unseasonal or even mildly out-of-range small tern in North America should be made the object of scrutiny. Most of them will turn out to be Leasts, but we can always hope.
Review all mystery birds to date.