Space use and ecology of goshawks in northern Idaho


Moser, Brian W.. (2007). Space use and ecology of goshawks in northern Idaho. Theses and Dissertations Collection, University of Idaho Library Digital Collections.

Space use and ecology of goshawks in northern Idaho
Moser, Brian W.
Goshawk--Habitat--Effect of logging on--Idaho Goshawk--Idaho--Remote sensing Goshawk--Conservation--Idaho
Natural Resources
The northern goshawk (Accipiter gentilis) has been the subject of considerable research and controversy over the past 25 years due to its requirement for closed-canopy forest conditions that are often targeted for timber harvest. Few data exist on the effects of timber harvest on goshawk reproduction. I conducted a quasi-experimental, before-after/control-impact study to examine the effects of timber harvest and weather on goshawk territory reoccupancy and nesting success. Classification trees showed that timber harvest did not affect goshawk nesting attempts as long as the 170-ha area surrounding the nest contained at least 39% potential nesting habitat following harvest. Nesting success was a function of April precipitation and January temperatures.;Little is known about goshawk space use in the northern Rocky Mountain region. I used computer simulations to study the effects of telemetry error on space-use estimates to determine whether estimates using satellite transmitters on goshawks would be reliable. I suggest a metric, the error ratio, to assess the adequacy of the telemetry system being used to estimate an animal's space use before a study is undertaken. Error ratios for goshawks indicated reliable estimates were achievable using satellite telemetry.;Goshawk home ranges and core areas were larger in my study than those in the southwestern U.S., and comparable to those in more northern latitudes. Female home ranges increased more than 2-fold during the nonbreeding season. However, females were residents and centered their home ranges near the previous years' nest. Breeding-season home range sizes were a function of nesting success and the proportions of openings and closed-canopy forest within the home range.;Resource selection studies that use samples of animal locations assume that space use is uniform. However, for central-place foragers, the null distribution is not uniform but rather a circular-normal distribution centered about the central place. I present a method for estimating a bias-corrected resource utilization function (RUF) that explicitly accounts for central-place foraging behavior. Advantages of the bias-corrected RUF include a less-biased picture of habitat selection by central-place foragers and the ability to map goshawk habitat using the resulting model without first needing to know nest-site locations.
Thesis (Ph. D., Natural Resources)--University of Idaho, May 2007.
Major Professor:
Edward O. Garton.
Defense Date:
May 2007.
Format Original:
xiii, 113 leaves :ill. (some col.) ;29 cm.

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