While both kites defend their territory, most territorial displays are performed by the male. Where conditions are such that an area can support multiple pairs of breeding kites, territorial areas must be demarcated by the occupants (8). Unlike other bird species that frequently move along the boundaries of their territories, kites spend many hours in a favorite perching spot near the nesting site. Thus, information about kite territories is most often obtained by the observation of an invading hunting bird, who is repeatedly chased away until out of the territory. (8). On very rare occasions, defensive action can result in physical contact between two kites. The wing of an opponent is held in the beak of the territorial kite, and the entwined birds unable to fly, tumble downward. After falling about half the distance to the earth, they separate and fly up to about one hundred and fifty feet off the ground to start again. (8). A descent to almost ground level has also been observed (3).
The most common defensive behavior is fluttering, both a high and a slow flutter in trees or bushes in the territory. In the case of the slow flutter, this behavior is most often seen as part of territorial establishment and courtship by the male. It is also performed during incubation or nesting if another male is trying to establish, or fluttering in, a territory nearby. Thus the slow flutter behavior may possibly serve two purposes as song does in other bird species, i.e. courtship and the securing of territory. (8)
Other agnostic behavior is communicated by bobbing the tail up and down. This display can occur more than a hundred times a day in some areas in response to trespassing by a variety of intruders (3).
With respect to other species of birds, Waian (8) found that little aggression occurred between kites and sparrow hawks or crows, although there have been a few reports of disruptive interactions between crows and kites. Twenty-eight species of other birds, except for red-winged blackbirds, were observed by Waian (8) to nest within fifty meters of kite nests with no negative encounters.
White-tailed Kite aggressively defend their territories against threatening bird species, such as red-tailed hawks, marsh hawks, red-shouldered hawks, barn owls, short-eared owls, common egrets, great blue herons and Cooper’s hawks. During these defensive actions, no physical contact seems to occur, and the attacks consist of a number of circling dives by the kite from above the invading bird. Some birds such as the red-tailed and red-shouldered hawks are considered to be the most threatening, and are intercepted at territory perimeters and chased far beyond the boundaries. (8).