White-tailed Kites: Roosting

Communal night roosting occurs frequently. When females are nesting, male kites may attend communal roosts (6). If a kite pair produces a second brood, the first brood normally roost together (6). Roosting communities may include more than the offspring of one kite pair, as well as non-breeding kites (6). In most cases, newly fledged birds comprise about two thirds of the roosting group especially as Fall approaches. Waian (8) observed an increase in roost sizes through Fall into Winter, reaching a maximum in January and decreasing in number until March. A great deal of variation was seen in roosting density: a eucalyptus tree was used by forty-eight birds, while forty kites spread out through twenty lemon trees. The spacing preferences in the trees appeared to vary from bird to bird. Some birds perched in the top and others moved further down into the tree, but the distance between birds was usually more than eighteen inches. (8)

On any evening, the first birds to arrive at the roost normally perch in high, open positions at or near the roosting tree. Before settling in for the night, the birds could circle above the roost, usually well after sunset. Any disturbance at this time could result in the entire group of birds moving to another site. Once settled, however, the birds are not easily disturbed. Roosting sites with more than about ten birds are typically located outside the territories of nesting birds, and may vary in location in any one season. (8)

The communal roosts may also provide the opportunity for pairs to bond. Waian (8) observed that few courtship displays, such as chasing and diving, were seen in the daytime territories of kites, yet there was an increase in such behavior at the winter communal roosts. Waian (8) noted that toward the end of winter, the number of kites that appeared to be pairing and looking for suitable territory and nesting sites were in fact more than the number that eventually settled in an area. Once established, all nesting pairs were territorial, and nested and hunted in their territories. Waian (8) found that kite territories could vary in size from eighteen to fifty-one hectares. While little information exists on inter-nesting distances (3), some reports have placed these distances at 160, 183, 293, 370(2x) and 153(3x) meters (3).