MANAGEMENT CONSIDERATIONS 



Sensible regulation of human activity with regard to breeding raptors requires knowledge of 

 two types. First, it is necessary to understand the breeding biology of the birds in the area where 

 human activity may occur; this knowledge is obtained through survey and monitoring efforts. 

 Second, it is important to know the sensitivity of different raptor species to disturbance, 

 identifying the stages in the life cycle when sensitivity is most acute. This knowledge is more 

 difficult to obtain, requiring sophisticated sampling and a large time investment, and is generally 

 beyond the resources available to managers. Information on response to disturbance is available 

 in the literature (see Bibliography). It should be kept in mind, however, that conditions vary in 

 space and time, and that the manner in which raptors respond to disturbance may vary 

 accordingly. 



Survey and Monitoring Efforts: Field surveys and monitoring will provide information on 

 habitat use, nest site use, nesting phenology, and reproductive success. Aerial and ground 

 surveys can be used to obtain these types of information (Call 1 978), but it is important to 

 minimize the disturbance to raptors during nesting studies in order to obtain accurate measures of 

 reproductive success (Fyfe and Olendorff 1976). Disturbance of nesting birds should be avoided 

 during nest-building, egg-laying, and incubation. Adults are least likely to abandon nests once 

 eggs have hatched. Low-flying fixed-wing aircraft are useful for survey and monitoring of 

 Golden Eagle, Prairie Falcon, Swainson's Hawk, and Ferruginous Hawk nests and appear to be 

 tolerated by nesting birds (Call 1978, Gilder and Wiehe 1977, Phillips and Beske 1990, Phillips 

 et al. 1990). Merlin nests must be located by ground surveys (Becker 1978, Call 1978), and this 

 approach is useful for locating nests of Northern Goshawk, Ferruginous Hawk, and Swainson's 

 Hawk. Nests approached from the ground could lead predators to nests (Call 1978, Fyfe and 

 Olendorff 1976). 



Response to Human Activity: Availability of quality disturbance-free habitat is probably the 

 most important variable for maintaining nesting raptors. Nesting sites and foraging sites around 

 nests need separate consideration (Call 1979). Recommended buffer zones, in which disturbance 

 should be avoided, are about 1 km or greater around nests (including noise disturbance) for the 

 raptors considered in this report (Suter and Joness 1981), and 400 m around important prey 

 concentrations. Ferruginous Hawks are generally considered the raptor most sensitive to nest 

 disturbance (Fyfe and Olendorff 1 976, Harmata 1991, Olendorff 1 993), however Northern 

 Goshawks are sensitive to low levels of canopy removal (Block et al. 1994, Crocker-Bedford 

 1990, Reynolds 1983) and may be precluded from nesting if dense stands of conifers are no 

 longer available. Old Black-billed Magpie nests are used extensively by Merlins for nesting 

 (Sieg and Becker 1990), and have been used as nest sites by other falcon species as well (Becker 

 1987, MacLaren et al. 1984). The importance of old corvid nests for a variety of diurnal and 

 nocturnal raptor species needs to be quantified, but the use of "artificial magpie nests" might help 

 mitigate disturbances at traditional nesting areas. Golden Eagles, Ferruginous Hawks, 

 Swainson's Hawks, and Prairie Falcons sometimes use artificial nest substrates (e.g.. Gilder and 

 Wiehe 1977, Olendorff 1993, Phillips and Beske 1990, Poppe et al. 1989, Schmutz et al. 1984); 

 use of artificial substrates may be a way to maintain nesting pairs in suitable habitat. Areas 



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