Northern goshawk broadcast surveys: Hawk response variables and survey cost

Abstract

We examined responses of Northern Goshawks (Accipter gentilis) to taped broadcast calls of conspecifics in tree-harvest areas and around alternate goshawk nests on Kaibab National Forest, Arizona, in 199 1 and 1992.Forest areas totaling 476 km2 were systematically surveyed for goshawks.Ninety responses by adult and juvenile goshawks were elicited and 15 active nests were located.NO difference in response rates between sexes was detected.Adult males, however, tended to approach the broadcaster without vocalizing, whereas adult females approached while vocalizing.Our success in finding active nests after getting responses from females was greater than after male responses.Goshawks responded more often to broadcasts during the nestling (2.0 responses/100 stations) than fledgling (1.0 responses/100 stations) period.During the fledgling period, adults were more likely to respond to broadcasts than juveniles.Total costs associated with our surveys for goshawks were $58-82 per km2 and $4.15-5.80 per broadcast station, depending on salaries.