Date of Award:
Master of Science (MS)
Gar W. Workman
The purpose of this study was to examine the effect of habitat parameters and human disturbance on the nesting success of goshawks, Cooper's hawks, and sharp-shinned hawks in an area within the Cache National Forest of Utah and Idaho. This research should provide the wildlife manager with information of value in planning recreation areas, roads, timber cuttings, and other activities where impacts are considered.
Of the three accipiter species studied, the goshawk showed the greatest preference for isolation from man. It nested at higher elevations (X=2,065 m); farther from human disturbance (X=250 m); higher in trees (X=12m)/ farther into cover (X=55 m) [generally in a mature forest]; and in proximity to water (X=394 m) with considerable horizontal visibility form the nest (X=53 m). The average number of young fledged from goshawk nests was 1.4.
The nesting Cooper's hawk was more tolerant to human disturbance (X=147 m); nested closest to water (X=220 m); at moderate elevation (X=1,782 m); and in average of 8 m above ground. Their range over-lapped that of recreational activities and also that of sharp-shinned hawks. Cooper's hawks fledged an average of 1.6 young per nest.
The sharp-shinned hawks nested farthest from water (X=444 m); at about the same elevation as Cooper's hawks (X= 1,789 m); closer to human disturbance (X=161 m); closer to the ground (X=6 m); and in nests with short horizontal visibility (X=14 m). The sharp-shinned hawks fledged an average of 2.1 young per nest.
As a general rule, all of the accipiters studied preferred to nest on the lower part of a north-facing slope with a well-developed tree canopy. Goshawks appeared to be most sensitive to man, while the Cooper's and sharp-shinned hawks were similar in habitat requirements and had nesting sites in closer proximity to human activities.
Hennessy, Stephen P., "Ecological Relationships of Accipiters in Northern Utah - With Special Emphasis on the Effects of Human Disturbance" (1978). All Graduate Theses and Dissertations. 3386.
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