Marsh kite, male, adult or nearly 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 type of kite you fly on a string. In fact, it’s the reverse. Birds were named first, and paper craft were named because they fluttered in the wind like those birds.
Kites belong to the falcon 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 descends to catch rodents, while the Mississippi kite mainly chases large insects through the air. Then there is the kite. Gliding low and slow over the marshes, it doesn’t need speed, since snails make up almost 100% of its diet.
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Kites are widespread in the American tropics, from Mexico and Cuba to Argentina, but in the United States they are restricted to the freshwater marshes of the Florida peninsula. For many years, birds in this population were known as Everglades kites, and they were long considered endangered. Their specialized prey, apple snails (genus Pomaceae), are sensitive to changes in water levels, so kites are nomadic in Florida, moving in search of marshes where snails are plentiful. During drought years, kites may not breed at all.
It is very difficult to get an accurate kite count, but direct census work since 1969 and extrapolated estimates since the late 1990s have given us a rough idea of population trends in Florida. Numbers have risen and fallen, with breeding success or failure partly due to changing water levels and snail populations. The kite may have numbered fewer than 100 in the early 1970s, but by 1997 the estimate was over 3,000. A sharp decline occurred after 1999, and by 2009 the estimate had fallen to below 800. Since then the population has increased again; in 2018, it was set at over 2,500.
And in a fascinating recent development, kites have extended their range north. Historically, they were almost entirely south of Orlando, primarily from Lake Okeechobee to the northern edge of Everglades National Park. Over the past few years, they’ve been showing up all over North Florida. In the Paynes Prairie area outside of Gainesville, for example, numbers have been present continuously for the past two years, with sightings of a dozen or more at a time.
Although the species is rightfully considered a Florida specialty, it has been sighted several times in Texas – no doubt straying birds north of eastern Mexico – and the Carolinas. With the recent increase in North Florida, it is almost certain to find it elsewhere in the southeastern states. Birdwatchers hoping to write local history should keep an eye out for wandering kites prospecting new areas.
Marsh kite, adult female. April in Osceola County, Florida. Photo by Brian E. Small
Regardless of their plumage, snail kites differ from all other North American raptors in their extremely fine, curved, hooked tip, perfect for extracting snails from curved shells. (The only beak shape that comes close is that of the hook-billed kite, a specialist in arboreal snails, but this bird looks very different in many other ways.) Adult female kites like this these are overall dull grayish brown, and can appear quite gray in some lights, but they do not approach the slate hue of the adult male. 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.
Marsh kite, juvenile. April in Osceola County, Florida. Photo by Brian E. Small
The fresh plumage of juvenile Kites is magnificent, with rich buff tones on the head and underparts and broad buff edges to the feathers of the upperparts. Peak nesting activity for snail kites in Florida runs from January through July. at any time. On this very young bird, note the buff spots and 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 mixture of yellow and gray.
Marsh kite, juvenile or immature. April in Osceola County, Florida. Photo by Brian E. Small
On landing, this young kite displays the broad, rounded wings and broad, short tail of the species: built for slow, soaring flight (as befits a bird foraging for snails), not for a strong pursuit. The white base of the tail is conspicuously visible. Seen from the side, flying at a distance, the white near the base of the tail and the low flight might suggest a Hen Harrier, but the long-winged, long-tailed shape of the Harrier is quite different. The combination of the snail’s shape, tail pattern, and especially beak shape should make it recognizable in any plumage, but individuals that stray from the usual limited range may be overlooked simply because that they are so unexpected.
Swamp Kite, immature male, April in Osceola County, Florida. Photo by Brian E. Small
It may take four or five years for a male kite to reach full adult plumage, with a completely gray body and head, and few or no pale barring in the flight feathers. During their first two years they are mostly brown, easily mistaken for females, as with the bird in this photo. This bird still shows buff-tipped feathers on the scapulars and coverts, reminiscent of juvenile plumage, but a few of the longer scapulars have moulted pure slate gray, indicating the general color the bird will wear as an adult male . The eyes have already turned quite bright red, but the cere, bare facial skin and feet are still yellow.
The new snail in town
Historically, kites in Florida ate almost exclusively Florida snail, an aquatic species 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 to appear in Florida waters. At least four non-native species of apple snail are now established, and some are becoming abundant and widespread.
Invasive species often cause major conservation issues, and these exotic snails are likely to damage Florida wetlands. But in the short term, they have a surprising effect: they support an increase in the snail kite population.
Exotic snails reproduce faster than natives, reproduce over a longer season, and may be more tolerant of pollutants. Adults may be too large for kites to handle, but kites readily take young, partially developed snails.
With this increased food source, the birds seem to breed and raise their young more successfully. This is thought to be a factor in the increase in their population since 2009.
And in a stunning twist, Florida kites are apparently evolving larger beak sizes – about 8% larger on average in recent years, according to one study. Natural selection favors large-beaked young, which now have greater survival, thriving on larger exotic snails. Sometimes an invasive species can bring unintended benefits.
