Identifying Snail Kite

Snail Kite
Snail Kite, male, adult or near adult. April in Osceola County, Florida. Photo by Brian E. Small

Upon hearing that there are birds called “kites,” many people assume they must have been named for the kind of kite you fly on a string. Actually, it’s the other way around. The birds were named first, and the paper contraptions were named because they floated on the wind like those birds.

Kites belong to the hawk family, but they are not all closely related, and they have different shapes, habits, and diets. Of the five kites found regularly north of Mexico, for example, the White-tailed Kite swoops down to catch rodents, while the Mississippi Kite mostly pursues large insects in midair. Then there’s the Snail Kite. Gliding low and slow above marshes, it has no need for speed, since snails make up close to 100 percent of its diet.

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Snail Kites are very widespread in the American tropics, from Mexico and Cuba to Argentina, but in the United States they are restricted to freshwater marshes of peninsular Florida. For many years, birds of this population were known as Everglades Kites, and they have long been considered endangered. Their specialized prey, apple snails (genus Pomacea), are sensitive to changes in water levels, so the kites are nomadic within Florida, moving around in search of marshes where the snails are numerous. In years of drought, Snail Kites may not breed at all.

It’s very difficult to get an accurate count of Snail Kites, but direct census work since 1969 and extrapolated estimates since the late 1990s have given us rough ideas of population trends in Florida. Numbers have risen and fallen, with breeding success or failure driven partly by changing water levels and snail populations. The kite may have numbered fewer than 100 in the early 1970s, but by 1997 the estimate was above 3,000. A sharp decline occurred after 1999, and by 2009, the estimate had fallen below 800. Since then, the population has been growing again; in 2018, it was pegged at over 2,500.

And in a fascinating recent development, the kites have been expanding their range northward. Historically, they were found almost entirely south of Orlando, mainly from Lake Okeechobee to the northern edge of Everglades National Park. Just within the last few years, they have been showing up all over northern Florida. In the Paynes Prairie area outside Gainesville, for example, numbers have been present continuously for the last couple of years, with sightings of a dozen or more at a time.

Although the species is rightly considered a Florida specialty, it has been sighted multiple times in Texas — undoubtedly birds straying north out of eastern Mexico — and in the Carolinas. With the recent increase in northern Florida, it is almost certain to be found elsewhere in the southeastern states. Sharp-eyed birders who hope to make local history should keep an eye out for wandering Snail Kites prospecting in new areas.

What to look for

Size and shape. A medium-sized raptor with broad, rounded wings and a short, broad tail.
Overall color. Adult males slate-gray; adult females grayish brown; juveniles warm brown to buff.
Tail pattern. White at base and narrowly at tip, with a very broad black subterminal band.
Bill shape. Moderately thick at the base but narrowing to a very thin, curved, hooked tip.
Colors of bare parts. Adult males have red eyes, cere, bare facial skin, and feet. Eyes of females and young vary from brownish red to brown, while the cere, facial skin, and feet are generally yellow.

Snail Kite
Snail Kite, adult female. April in Osceola County, Florida. Photo by Brian E. Small

In any plumage, Snail Kites differ from all other North American raptors in the extremely thin, curved, hooked tip to the bill, perfect for prying snails out of curved shells. (The only bill shape that comes close is that of the Hook-billed Kite, a specialist on tree snails, but that bird looks very different in a variety of other ways.) Adult female Snail Kites like this one are dull grayish brown overall, and may look quite gray in some lights, but they don’t approach the adult male’s slaty hue. The eyes vary from brown to brownish red, but the cere, facial skin, and legs are yellow to pale orange, not orange-red to red as in the adult male.

 

Snail Kite
Snail Kite, juvenile. April in Osceola County, Florida. Photo by Brian E. Small

Fresh plumage in juvenile Snail Kites is beautiful, with rich buff tones on the head and underparts and broad buff edges on the feathers of the upperparts. Peak nesting activity for Snail Kites in Florida ranges from January to July, so freshly fledged juveniles are most likely to be seen from late spring to early fall, but some nesting activity is possible in any month of the year, so juveniles might be seen at any time. On this very young bird, note the buff spots and the tips of the wing coverts, and the buff tips to the primaries. The eyes are still dark brown, and the bare facial skin is a mix of yellow and gray.

 

Snail Kite
Snail Kite, juvenile or immature. April in Osceola County, Florida. Photo by Brian E. Small

Coming in to land, this young Snail Kite displays the broad, rounded wings and broad, short tail of the species: built for slow, gliding flight (as befits a bird that seeks snails), not for powerful pursuit. The white base of the tail is strikingly conspicuous. Seen from the side, flying at a distance, the white near the tail base and the low flight might suggest a Northern Harrier, but the harrier’s long-winged, long-tailed shape is very different. The Snail Kite’s combination of shape, tail pattern, and especially bill shape should make it recognizable in any plumage, but individuals that stray outside of the usual limited range might be overlooked simply because they are so unexpected.

Snail Kite
Snail Kite, immature male, April in Osceola County, Florida. Photo by Brian E. Small

It may take four or five years for a male Snail Kite to achieve full adult plumage, with completely gray body and head, and little or no pale barring in the flight feathers. For their first couple of years, they are largely brown, easily mistaken for females, as with the bird in this photo. This bird still shows some buff-tipped feathers on the scapulars and coverts, reminiscent of juvenile plumage, but a couple of the longest scapulars have molted in pure slate-gray, indicating the overall color the bird will wear as an adult male. The eyes have already turned a fairly bright red but the cere, bare facial skin, and feet are all still yellow.

The new snail in town

Historically, Snail Kites in Florida dined almost exclusively on the Florida apple snail, an aquatic species about the size of a golf ball. But in the early 2000s, larger, exotic apple snails, native to South America and escaped from the aquarium trade, began showing up in Florida waters. At least four non-native apple snail species are now established, and some are becoming abundant and widespread.

Invasive species often cause major conservation problems, and it’s likely that these exotic snails will damage Florida wetlands. But in the short term, they’re having a surprising effect: They’re supporting an increase in the Snail Kite population.

The exotic snails reproduce more rapidly than the native one, breed over a longer season, and may be more tolerant of pollutants. The adults may be too large for Snail Kites to handle, but the kites readily take partially grown young snails.

With this increased food source, the birds seem to be breeding and raising young more successfully. This is thought to be a factor in their population increase since 2009.

And in an astounding twist, Florida Snail Kites apparently are evolving larger bill sizes — about 8 percent larger on average in recent years, according to one study. Natural selection is favoring the larger-billed young, which now have greater survival, thriving on the larger exotic snails. Occasionally, an invasive species may bring unforeseen benefits.

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Kenn Kaufman

Kenn Kaufman

Kenn Kaufman is an expert birder and naturalist, a talented artist and photographer, a world traveler, and the author of many books about birds and other wildlife. His column “ID Tips” appears in every issue of BirdWatching. Kenn is also a field editor for Audubon Magazine and a contributor to Birds and Blooms. His work first appeared in Birder’s World (now BirdWatching) in April 1988. Visit his website, Kaufman Field Guides.

Kenn Kaufman on social media

Brian E. Small

Brian E. Small

Brian Small is a Los Angeles-based bird and nature photographer whose photos appear in the “ID Tips” column in every issue of BirdWatching. His work has been published in Time, The New York Times, Audubon, Nature Conservancy, National Wildlife, Wildlife Conservation, and many other publications. His photos also illustrate many field guides, including Kenn Kaufman’s Birds of North America, a series of state bird identification guides published with the American Birding Association, and his own Eastern and Western photographic field guides to the birds of North America published in 2009 with author Paul Sterry and Princeton University Press.

Brian E. Small on social media