Observations on the Food and Nesting of the Broad-Winged Hawk (Buteo platypterus) in Northeastern Kansas

Abstract

Since the University of Kansas Natural History Reservation was established as a natural area in the northeastern corner of Douglas County, Kansas, in 1948, rapid successional changes have occurred. Many species have changed their status on the area. One such species is the Broad-winged Hawk (Buteo platypterus). During the early years of the Reservation , it was conspicuous, but after 1965, its numbers suddenly decreased and it no longer occurs there regular&. Broad-winged Hawks were seen frequently only in the northwestern Dart of the Reservation. This flat hilltop with old pastures of tall grass and clumps of brush gives way to steep hillsides of southern exposure , having a xeric woodland dominated by honey locust (Gleditsia triacanthos) and osage orange (Maclura pomifera) Dogwood (Cornus &urn-mom&i), plum (Prunus americana), sumac (Rhus glahru), and crabapple (Malus ioensis) form thickets in abandoned fields and at the edge of woodland. Elm, hickory, and oak dominate more mesic woodlands. SCHEDULE The Broad-winged Hawk is a summer resident of the Reservation. Fourteen recorded arrival dates from I950 through 1965 ranged from 13 Auril to 28 Anril. with an average of 19 April. In 1962 the hawks were seen less frequently than before. After 1965, they were not seen regularly and there was no assurance that any particular record represented an arrival date. The timing of three nestings observed on the Reservation in 1954, 1957, and 1958 varied only a few days. The hawks established territories, acquired mates, and built nests quickly. By the end of April, the birds were laying eggs. Riley (The Osprey 6:21, 1902), quoted by Bent (Life histories of American birds of prey. Order Falconiformes. Part I. Dover Publications, Inc., New York, 1961), described a more lengthy nest-building period than was recorded on the Reservation in 1954. 1957. and 1958. Broad-winged Hawks on the Reservation were seen to hunt by watching from a low and inconspicuous perch on a fence post or in a tree, from which prey was detected and taken with a sudden short glide. On 4 May 1957, a hawk was blushed from a nest, Prey was observed in nests or sometimes was with-an d on 9 June eggshell was found beneath this drawn with spatulate forceps from crops of the nest. On 11 June, when the nest was examined for nestlings. After identification, such morsels were the first time, there were three nestlings. The largest refed to the hawks. Remains found in the pellets weighed 73 g and the smallest, appearing to be newly disgorged at the nest usually seemed to be the same hatched, weighed 27 g. Bent (op. cit.) stated that individual prey animals found earlier at the nests. incubation is between 21 and 25 days, but possibly In a few instances there was no possibility of duplica-this was an underestimate.