I was able to reach Ken Meyer who does the SWKI research. Below is his
reply about aging the kites.
Tommie Rogers
Mound City, MO



> Hi Tommie,
>
> Surprised but glad to hear about your local Swallow-tailed Kite. Most (at
> least the older birds) are on their way to south-central Brazil (and
> adjacent Bolivia and Paraguay) for the winter. It takes them awhile, but
> by now, the majority of adlts are somewhere between Mexico's Yucatan
> Peninsula and Colombia. Most of the kites remaining in the U.S. are young
> of this year, but they'll be gone by mid-September.
>
> Yes, the best way to distinguish young of the year is by the shorter tail.
> Molting adults, however, can have short tails as well at this time of
> year. The way to tell if a short-tailed bird is an adult is to look at
> the trailing edge of the wing. Adults will be molting (or about to molt)
> their wing feathers, so you'll see either gaps where wing feathers have
> already dropped out or an uneven trailing egde resulting from the
> loosening of feathers about to drop. The wing of a young kite, however,
> will look very even along the trailing edge. The difference in wing
> plumage is quite obvious. If you look closely, you'll also see that the
> ratio of black to white plumage on the underside of a young kite's wing is
> smaller than for an adult. That is, the amount of black flight feathers
> extending rearward from the white underwing coverts is less than in an
> adult. Taken all together, these features make a juvenile's wing
> distinguishable from that of an adult.
>
> Good to hear from you, and thanks for the kind words. Yes, still studying
> Swallow-tailed Kites (heading to the Amazon region in two weeks to look
> for radio-tagged kites) plus Short-tailed Hawks, White-crowned Pigeons,
> Snail Kites, mangrove birds in the Keys, and Jabiru Storks in Central
> America. Busy, but having lots of fun.
>
> Best regards,
> Ken

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