A study of how a bird almost became extinct in the 1930s, some 30 years before its wetlands habitat, started disappearing faster than it ever had before, and 30 years before the human population started growing rapidly. The irony is that the White-tailed Kite's population became more stabilized during the time that the human population was rapidly growing and the habitat was disappearing. Over a thirty year period California eliminated approximately 90% of its wetlands, and the White-tailed Kite population grew.

The most primitive of the eight groups or subfamilies of diurnal birds of prey are the kites, which occur in most of the warmer regions of the world. They are long-winged and mostly long-tailed birds that are particularly adept at soaring, circling and gliding. They habitually work their way languidly over semi-open country, often in groups, their wings cocked at a slight dihedral angle.

The "black shoulder" is the common marking of this group, which is widely but erratically distributed throughout the warmer parts of the globe in steppe, desert, savanna, and the tropical forest. Four species are very similar, except for the slight variations in the underwing patterns. Three of them are considered by some ornithologists to be geographical representatives of a single species.

The White-tailed Kite (Elanus leucurus) about 16 inches in length, ranges from the southern borders of the United States through much of South America. Both sexes participate in nest construction, and four eggs are normally laid. Incubation requires up to 32 days, with both parents taking part. The young remain on the nest for about a month and then return to it for some time thereafter to obtain food.

The White-tailed Kite builds a bulky nest of small fine twigs, deeply hollowed, and about 18 to 59 feet high in the top of an oak, willow, eucalyptus, or other deciduous tree. Both sexes take part in building, incubating eggs (about 30 days), and raising young, and the more aggressive individuals defend the nest. In southern California these kites group together in communities. They do not object to pairs of the same species building within 200 yards of their own nest, but the territorial boundaries are strictly observed. ... The normal egg clutch for Elanus is four, but varies from three to six.

As in other species of Elanus, food includes small mammals (field mice, wood rats, pocket gophers, ground squirrels, shrews), reptiles, amphibians, and insects. They show a decided preference for living in the vicinity of fresh-water marshes and streams where food is readily available all through the year, and probably do not wander far, even in winter.

In the New World the White-tailed Kite often soars at a height of 60 or 70 feet while looking for prey on the ground. Remaining poised for half a minute at a time the bird then drops downward in an extended parachute maneuver to make the kill. Often it indulges in a pretty fluttering flight with quick wing beats. The display flight used in the nesting territory is a slow beating of the air with short strokes, the wings held at a sharp angle above the back, and the legs dangling.

The occurrence of the White-tailed Kite is closely related to the presence of voles and mice, and when the prey is depleted kites depart that area. Numbers and range seem to expand and contract in broad cycles, possibly tied to the abundance of its favored prey, the California Vole. For this reason the population is apparently cyclical in numbers, and breeding distribution may always be sporadic and unpredictable.

Because Kites tend to be nomadic and to decrease or increase rapidly with fluctuating vole populations, future atlasers should be very cautious in interpreting any changes they detect when they repeat the Marin atlas at a later date.

Open, cultivated and marshy bottomlands with scattered tall trees; savannah; grassy foothill slopes interspersed with oaks; agricultural areas with trees for windbreaks; orchards; and roadside verges (for hunting). They are found mainly in the Upper Sonoran Life Zone below 2000 feet, but wanderers occasionally occur in the mountains.

Breeding Habitat: Savanna, riparian woodland, marsh, partially cleared or cultivated fields, grassy foothills.

Habitat: Of two sorts: low rolling foothills or valley margins grown scatteringly to valley or live oaks; and river bottomlands or marshes adjacent to, or inclusive of, broken or scattering deciduous woodland. An essential combination of conditions seems to be open grasslands, meadows or marshes for foraging, primarily for meadow mice, and near-by isolated dense-topped trees for perching and nesting.

Uncommon to locally fairly common resident. Although it is probably not truly migratory, the population scatters widely during the non-breeding season. Until recently winter roosts of more than 100 concentrated the population in localities from the Sacramento Valley and San Francisco Bay area south to San Diego County. Most out-of-range wanderers appear during fall, winter and spring.

The North American population has not been numerous in historic times and long ago disappeared from the southern part of the United States, except in Texas and California, west of the desert from the upper Sacramento Valley to the San Diego area. By 1900 the White-tailed Kite was considered rare in California and was protected by state law. Its beautifully marked eggs, some with a cap of brown coloring at one end, are prized by oologists. Part of the survival problem of this evidently dying species, like that of the Swallow-tailed Kite, has been interference by humans.

Note: In recent years there had been an encouraging upsurge in the California population of these kites (which leveled off in the mid-1970s). This increase was probably due to an increase in the microtine rodent population as the result of new water projects, increased irrigation and the spread of agriculture. However, there was a steady and steep decline in coastal and near coastal southern California populations during the 1980s. Once the population leveled off, sharp local population fluctuations occurred, reflecting perhaps the cyclical situation in local rodent population. In some areas, the upswing in White-tailed Kites also indicated a reduction of local native floras and faunas due to conversion of indigenous vegetation to agriculture, and the expansion of conditions favoring both mice and kites. However, during the 1980s, the rapid urbanization of southern California and west-central California encroached upon agricultural lands, and may explain the movement of some kites to peripheral and marginal habitats (as into the fringes of the deserts), and the precipitous decline in areas where during the 1960s and 1970s they were fairly common. In some agricultural areas of the interior valleys, where kite populations were increasing during the 1960s and 1970s, conversion of crops favorable to microtine rodents resulted in unsuitable plantings of cotton, grapes and fruit orchards. Additionally, windbreaks, which served as nesting trees for the kites, were diminished.

Winters within US. North American range greatly expanded since 1960; probably only raptor to have benefited from agricultural expansion. Aided by high adaptability to habitat disruption and increased abundance of rodents.

Once considered endangered in California, the White-tailed Kite has made a great comeback in the state, being the only raptor to benefit from the spread of agriculture and the concurrent population explosion of its favored prey.

Distribution: Tropical America, except the West Indies; north in the United States to about the latitude of San Francisco on the Pacific coast, St. Louis in the interior, and South Carolina in the east.

The kites are resident in the oak groves of Santa Clara Valley, and frequent the marshes about San Francisco Bay, where Mr. W. K. Fisher has found them catching large numbers of the California meadow mouse.

It used to be particularly numerous around San Francisco Bay; but it is now everywhere very much reduced in numbers and restricted in range, with promise of an early extinction.

Recent ornithological literature bristles with records of occurances of the White-tailed Kite, once upon the verge of extinction, but, now, it is believed, being slowly nursed back into life. The cause of the near tragedy, now hopefully averted, was expressed several years ago by Dr. Grinnell: "With no doubt whatever, the present rarity of this hawk in California is due to the associational preference for marshes, where its habit of flying slowly back and forth at a moderate height above the ground in the lookout for meadow mice and insects makes it an easy target for the thoughtless hunter. In my experience the average sportsman is still unenlightened enough to shoot down any sort of 'hawk' that flies his way, provided game is not at the moment expected." Yet this is the bird of which Cooper (following Heermann) could write in the Sixties: "This beautful and harmless species is quite abundant in the middle districts of California, remaining in large numbers during winter among the extensive tule marshes of the Sacramento and other valleys."

There are probably not more than fifty pairs left in California and in spite of protection by law the number is slowly decreasing.

It is found over tree-dotted prairies and savannas, marshes, and semi-open valleys. Though fifty years ago it was common, it has decreased steadily until now it is to be classed among our unusual birds. Despite the fact that it has been afforded protection in recent years, the species does not seem able to increase.

The White-tailed Kite is found in California from the upper Sacramento Valley and Humboldt County, south to northern Baja California and from Texas, Oklahoma, and Florida to Guatemala.

Resident throughout year within metropolis of range; but shifts about locally, both seasonally and from year to year, in accordance with food supply. Formerly, prior to about 1895, common and widespread in valley and lower foothill territory, but now rare or entirely gone from many sections. A slight trend toward recovery, in area and numbers, is latterly in evidence.

This gentle and attractive bird seems to have become exceedingly rare, or to have been entirely extirpated, in the eastern portions of its North American range. During my six seasons, or parts of seasons, spent in various portions of Florida I have never seen this kite; once a special trip was made to a section where our guide said they had recently nested, but no sign of them was found. Donald J. Nicholson tells me that he has not seen one there since 1910. We could not find it in southern Texas, and I have no recent records of it there. In certain sections of California it seems to be holding its own, though exceedingly local in its distribution, and nowhere universally abundant. I doubt if it ever was very abundant, although Cooper (1870) referred to it as "quite abundant in the middle districts of California, remaining in large numbers during winter among the extensive tule marshes of the Sacramento and other valleys", and Belding (1890) considered it "still a common resident" about these marshes "in the centre of the State." But Belding quotes Dr. B. W. Evermann, as calling it "a rare resident" in Ventura County, as early as 1886; and he quotes W. E. Bryant as saying that "it is still a very rare resident" in Alameda County. It seemed to be the general opinion, at that time, that the white-tailed kite was a disappearing species. As a result, it has since been rigidly protected by law and exempted from collecting permits.

"Now comes more recent light on the subject, which is more encouraging. Dr. Gayle B. Pickwell (1930) has published the results of his exhaustive study of the literature and his field work in the Santa Clara Valley. Referring to past and present conditions in that region, he says:

"In spite of the fact that Taylor, in 1889, wrote of the Kite, "I venture to assert that there are not more than four pairs this year breeding within a radius of seven miles of that city (San Jose)", today, forty-one years later, there are still that many or more.

Let us estimate that an average of four pairs of Kites (too high an estimate for some, too low, perhaps, for others) frequents each. We have then sixteen pairs of Kites in this entire valley. Twenty pairs, forty birds, I feel convinced, account for every Kite from Gilroy to the Bay and from Mount Hamilton to the summit of the Santa Cruz Mountains.

The Kite was certainly more numerous In San Joaquin and Sacramento counties forty to sixty years ago than it is now. In other regions where it was present, especially in marsh districts, undoubtedly It has been seriously reduced In numbers. The condition in hill sections inhabited by it can be but guessed at. Here it probably has suffered least.

This Kite is probably a dying species, never within historical times having predominated as such raptorial birds as the Desert Sparrow Hawk or Red-tailed Hawk for instance.

Since the above was written Dr. Pickwell (1932) has published a "requiem" for the kites in this valley; whereas he estimated that there were possibly 16 to 20 of these kites in the Santa Clara Valley in 1928, he now says: "This day (October 30, 1931) there cannot be more than two or three, and all too possibly none." We hope that this is a mere local condition.

His observations on the home life of these kites were made in the foothills of the Mount Hamilton Range in Santa Clara County:

The Slatore ranch lies in the foothills whose summits are grass-covered with wild oats and bromes, with scattered valley oaks and live oaks, and here and there a cluster of California coffee berry (Rhamnus catiforaica) and gnarled Sambucus. Rocky outcrops, where more moisture may be trapped, have curious copses of scrubby growths of toyon, holly-leaved cherry, sages and sage brush; and the gullies lined with buckeye, California laurel, and poison oak run down to Silver Creek where the laurels and willows predominate. But the hills are mostly smooth as velvet, golden velvet most of the year, and green oaks are scattered over the velvet, like buttons on a buxom vest. In three buttons on this velvet vest were occupied nests of the White-tailed Kite.

That such a habitat is not an unusual Kite home is shown by the fact that all the Kites of Santa Clara Valley today are, excepting one or two pairs, restricted to the lower foothills of the Mount Hamilton Range and Santa Cruz Mountains, on either side of the north end of the Valley. The exception is of not more than two pairs that occur to the north of San Jose between that city and the Alviso salt marshes. These frequent the cottonwoods and eucalyptus trees of the Coyote Creek and, not infrequently, are seen hunting over the treeless marshes at the foot of the Bay in common with Marsh Hawks, native there, and Turkey Vultures and Red-tailed Hawks from the hills.

Bendire (1892) says of their haunts: "Their usual resorts during the breeding season are the banks of streams or the fresh water marshes, especially if a few scattered live oaks or willow groves are close by, and their favorite nesting sites are the tops of live oaks, although other trees are also made use of whose foliage securely conceals the nest during incubation."

The impression I gained from men I talked with in California and from my own limited experience there was that this kite shows a decided preference for the vicinity of water, fresh-water marshes and streams; in such places it finds its food readily available all through the year, and it probably does not wander far away even in winter. According to Audubon (1840) it was found in similar haunts in Texas and Florida.

A rare and beautiful hawk now almost extinct in the Southeast, a few in Texas and California. Reapears in South America.

Historical Occurrence

The overall distribution has dramatically changed over the past century. The increase in voles with the cutting of forests for agriculture has benefited this species. Once considered so rare that it was one of only five species fully protected under California law (along with the California Condor, Bald Eagle, Peregrine Falcon, and Trumpeter Swan; Fish & Game Code), the species has greatly expanded throughout the southern United States since 1960. In Monterey County kites were known from the Carmel Valley for years but the occurrence in the upper Salinas Valley is recent. No birds were recorded there by Willett (1908) but one bird was noted along the Nacimiento River on Camp Roberts by Mowbray (1947). Likewise, the spread to the Big Sur coast is recent, as the species was not seen by Jenkins (1906) or Pemberton & Carriger (1915). At Hastings Reservation, in the upper Carmel watershed, habitat is marginal for this species and kites occurred in only 17 of the 43 years between 1938-1980 and nested in only five of those years.

Early declines were apparently caused by shooting, habitat loss, and perhaps by overzealous egg collectors. The eggs were highly prized because of their scarcity, because of the variability between egg sets, and because Black-shouldered Kite eggs are among the most beautiful of those of all North American birds. Illegal egg collecting continued until at least 1940 despite laws passed in 1905 to protect the birds and their nests (Williams 1940); further protection was afforded by legislation in 1957. California's Kite population has apparently increased because of the birds' ability to tolerate habitat fragmentation caused by agricultural practices, to exploit increased Microtus populations thriving in fields irrigated year round, and to reproduce at a high rate. A clutch size of four to five eggs and the ability to double brood in a single year are both unusual adaptations for a hawk ... Martin (1989) noted that the amount of irrigated agricultural land in California increased by 42% from 1944 to 1978, coinciding with the period of dramatically increasing Kite numbers.

The great year-to-year fluctuations in Kite numbers appear, at least in part, to be tied to similar changes in the prey base influenced by rainfall. Pruett-Jones et al. (1980) found a significant positive correlation between Kite numbers and rainfall. This perhaps is explained by the fact that microtene rodents need standing water to reproduce ... and that their numbers are usually reduced in a drought. The decline in Kite numbers in California during the 1975-76 to 1976-77 drought and the substantial increase in numbers in Oregon at that time, including their first breeding record ... further suggests a link between rainfall, vole populations, and Kite populations.