Where there is a decrease in habitat size, competing species such as great horned owls, red-tailed hawks, red-shouldered hawks, and Swainson’s hawks may be a deterrent to kite nesting in that area (6). The primary reasons for lack of breeding success, besides egg loss to harsh weather, are predation of eggs, young and parents by other birds and raptors, and disturbance by human encroachment (6). In California, competing species (3) and a high loss of about ninety percent of riparian habitat (6) are having a detrimental effect on kite populations in parts of the state. Between 1982 and 1991, kite numbers have decreased in eleven of fourteen regions in California, with the most significant reduction of approximately forty percent in southern Californian grasslands (3).
Additionally, because many kites live near pastoral and agricultural areas, they are dependent upon farming practices used in those areas. Where prey is abundant, kites benefit; where prey is less abundant or where agricultural land is being converted to urban use, population numbers will be affected. Tree reduction or pesticide use may also affect kite reproduction. In some areas, kite numbers have increased because of some kinds of agricultural activity. (6)
There is concern about the rapid loss of suitable breeding habitat for White-tailed Kite and a lack of specific information and current studies of the species (5, 6).