The small nestlings are generally silent, but when handled or otherwise disturbed, they give soft lisping peeps. By early August, when the young have ventured from the nest bowl to nearby branches, they become vocal and their calls can be heard more often than those of the adults. The call of the adult has been well rendered by Sutton (1939:43) with the syllables "phee phew"—a whistle in which the first syllable is short (lasting only about one-fourth of a second) with a rising inflection, clipped off short, while the second syllable has a downward inflection, and is drawn out to two or three times the length of the first syllable. The call of the fledgling is soft, with a lisping quality; that of the adult is much like it but is sharper and more piercing. Fledglings call frequently while waiting to be fed, but as an adult approaches with food, the calls are given in rapid succession and slurred to a high thin squablike [squeaking] or squealing.
When fledglings are able to fly and have left the nest, the adults generally pass food to them directly, rather than dropping the regurgitated mass, which might fall to the ground and be lost. On August 22 a fledgling was seen following an adult in flight, and was also seen to eat while it was flying. At this stage, when an adult fed one young of a brood, the other would sometimes fly to the spot in an attempt to share the meal. However, the transfer of food was usually rapid and the adult would leave within a few seconds. Young often were seen to fly out from the nest tree and maneuver in the vicinity, flying in a roughly circular course perhaps 100 feet in diameter and then returning to the nest tree, thereby familiarizing themselves with their surroundings.
According to the consensus of published accounts, there are usually two eggs per clutch, occasionally one or three. However, Ganier (1902:89), who studied the species in Mississippi, wrote: "Of all the nests I have examined [number unspecified] only one was found to contain more than a single egg." Nice (1931:69) recorded 19 sets of two each and seven of one each in Oklahoma. In the course of my observations, 12 clutches of two were recorded. A group of four fledglings were observed concentrating their activities at a nest more than 200 feet from any other known nests; possibly all belonged to the same brood, but this was not definitely determined.
Many of the nests that were in use in 1961 appeared to be relics from earlier years, as the material was darkened and disintegrating, but probably a new layer of sticks had been added on the top. Bent (op. cit.:65) mentioned this kite's habit of frequently using the same nest in successive years. On one occasion as I drove over a little-used road in the Park and passed a cottonwood grove where kites were nesting, one of the birds swooped down and struck the top of the automobile. In a subsequent conversation, Harry Smith asked me if this had happened, and said that this particular kite had struck his truck frequently when he drove past its nest. This had occurred at the same place in three successive years, and Smith was convinced that the same kite had used the nest each year, although the bird was not recognizable except by its unusually aggressive behavior. On dozens of occasions in the course of my observations kites swooped at me when I was near their nests, but, except for this one individual, they always veered away at a distance of several feet or several yards.
At the time of my visit to the Park in early June, kites were relatively silent and secretive in their behavior. Approximately half of those that were incubating flushed when a person walked near the tree, but others continued to sit on their eggs until a person had climbed to within a few feet of the nest. Upon being flushed, such a kite, in 50 per cent of observed instances, swooped at least once at the intruder, but some of the kites would soar overhead, watching without making any active defense. At the time of my next visit, July 18 to 21, when the kites were feeding well grown nestlings, behavior at the nest was much different. As soon as a nest was located the parents began scolding and swooping. At the first nest observed, a group of eight kites had congregated within two minutes to scold and harass the intruders. Even kites whose nests were kept under observation frequently, never became fully reconciled to the intrusion but there was much difference between individuals in this respect. Some were reluctant to deliver food and, having secured prey, would fly about in the vicinity without coming to the nest.
Mortality Factors and Defense
Joint defense against a common enemy was noted on July 21, 1961, when 21 kites were seen swooping at a Swainson's hawk perched near the top of a large cottonwood, where it was partly protected by foliage and branches. When I flushed the hawk, it was pursued and [harassed] by the kites, some of which followed it for nearly a quarter mile although there were no nests of the kites nearby. On August 4 a group of six kites was seen heckling a fledgling Swainson's hawk, which crouched among thick foliage in the top of a tall cottonwood, as the kites swooped at it, sometimes brushing it with their wings when they swept past. Dr. Hibbard mentioned an instance in which a horned owl was flushed, and was chased and heckled by a red-tailed hawk and by a group of kites. The latter seemed to regard the owl as the greater enemy, but ordinarily any large raptor arouses their hostility.
Because of their exceptionally swift and skillful flight, the adult kites have few natural enemies, but the eggs or nestlings are vulnerable to such enemies as crows, jays, the larger hawks and owls, and to certain mammalian predators, notably raccoons. Also, many nests probably are destroyed by the sudden and violent summer storms that are characteristic of the High Plains. Bendire (1892:178) cited observations by Goss that in a hailstorm in Barber County, Kansas, eggs were destroyed in many kites' nests and some of the nests were almost completely demolished. Several nests found by me to have incubating eggs in the first week of June were abandoned or had disappeared completely by July 18, but the cause was not evident. One nest that was under observation on July 22 had nestlings approximately two-thirds grown on that date, but on August 4 only a few sticks remained, and the carcass of a fledgling dangled from a limb ten feet below the nest. Even at the Park where firearms are prohibited, kites are sometimes shot by ignorant or malicious persons. In general, Kansas ranchers recognize the harmless and beneficial habits of kites, appreciate their esthetic appeal and protect them, but many persons use them as convenient targets, with utter disregard for the Federal laws protecting them. Because of the strong popular prejudice against raptorial birds in general, laws protecting them are usually not enforced. Law enforcement officers do not take action even when clear-cut violations come to their attention. Arrest and prosecution for the killing of any kind of raptor is almost out of the question in Kansas.
Ratio of Immatures to Adults
In the juvenal plumage flight feathers of the kites are brown, barred with white, much different in appearance from the dark, slaty plumage of adults. Bent (op. cit.:67) stated that these barred flight feathers are retained through the second summer, and he quoted Mr. G. W. Stevens as having found kites breeding in this immature plumage. On June 2, 1961, I attempted to determine the ratio of these yearling kites to others in the population at the Park. Most of the kites seen were in flight too far away to discern definitely whether or not they were juveniles, and records were limited to those seen at relatively close range. In a total of 108 records only 11 pertained to these yearlings and the remaining 97 were identified as of adults. Beyond doubt in the course of my counts some individuals were recorded repeatedly, therefore the counts are not entirely acceptable. However, on each occasion that kites were seen in numbers in early summer, the adults greatly outnumbered the juveniles. The approximate nine to one ratio of adults to yearlings seems much too high. Even if the difference is much less than indicated, the high ratio of adults to yearlings would seem to imply that the adults have a long life expectancy. A rather improbable alternative is that some of the yearlings remain in winter quarters or wander elsewhere rather than accompanying the adults on the return migration to their breeding grounds. Still another alternative is that the breeding season of 1960 was relatively unsuccessful, but this idea is negated by my own observations at the Park in late 1960, as recently fledged young were numerous then.