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Experlmental Eagle Classification 



Occasional requests for data on the status of eagles (Haliaetus 

 leucooephalus and Aquila chrysaetos) in Montana have clearly demonstrated 

 the need for information on population recruitment, which in turn reflects 

 species welfare. The usual technique is to climb into eagle eyries and 

 count eggs or chicks. This technique is considered inappropriate for 

 general use for the following reasons: 1) it is time-consuming since 

 eyries must be located and substantial time and equipment are necessary 

 for subsequent inspection; the volume of data collected per unit of 

 effort expended is low; 2) nesting and/or hatching success are not 

 reliable indicators of fledging success; and 3) nest site disturbance 

 may result in some unknown mortality, thereby artificially reducing 

 fledging success. A technique utilizing age-classified field observations 

 at biologically important phases of annual cycles of eagles seems more 

 appropriate for more extensive field use. 



Objectives of this study are to: 



1) determine the feasibility of assessing population recruitment of golden 

 eagles based on changing immature/mature ratios during the course of 



a year; 



2) determine immature/mature ratios for wintering bald eagles; and 



3) attempt to detect different migration patterns for mature and immature 

 bald eagles. 



The principle investigator and four cooperators (Ron Paulick, Chris 

 Servheen, Jon Swenson and John Ciralll) will record eagle observations 

 throughout 1978 (Appendix V). 



Ferruginous Hawk jButeo regalis) Investigations 



The ferruginous hawk is a large buteo of the western plains. It is no 

 longer as abundant as it was In the early part of this century. Loss 

 of suitable grassland habitat to agricultural practices is probably a 

 primary reason for the apparent population reduction. 



The status of the ferruginous hawk in Montana is completely unknown. 

 Fourteen nests were located in Beaverhead County in 1977, two of which 

 contained chicks (2 and 3) while the others were vacant. Efforts to 

 assess the status of this species will be continued as time and available 

 manpower permit. 



The problem of nest desertion Is acute where this species is subjected 

 to human disturbance (Davy 1930, Howard and Powers 1973, Olendorff 1973, 

 Smith and Murphy 1973). During egg-laying and incubation periods, these 

 birds will generally abandon their nest if any human activity occurs 

 within close proximity of the nest site. Once the young have hatched, the 

 probability of desertion is very slight. With respect to this problem. 

 Snow (1974:14) stated: "With the increasing demand on public lands for 

 resource development and recreation, human activity in areas with nesting 

 populations of ferruginous hawks may become a severe limiting factor if 

 such activity occurs during the period before the young hawks have hatched. 



