RESULTS AND DISCUSSION 



A total of 42 concentrations of cliffs, termed "cliff sites" (see Appendix 1), comprising >300 

 individual outcrops, was surveyed for nesting raptors in June and early July 1 994 in the Montana 

 units of the Sioux District. Only four sites appeared to be in use (see Appendix 2) at the time of 

 the survey (two sites in the Chalk Buttes and two sites in the Ekalaka Hills); three sites were 

 used by Prairie Falcons and one by a pair of Merlins. No field survey was conducted in South 

 Dakota in 1994. 



Element Occurrence (EO) Records for the Harding County, South Dakota portions of the 

 Sioux District, obtained from the South Dakota Natural Heritage Program (see Appendix 3), 

 provided locations for 50 Golden Eagle nests, 1 1 Merlin nests, and 13 Prairie Falcon nests in use 

 between 1973 and 1989. Some of the nest sites are known to have been used in multiple years. 

 Evidence also exists for Northern Goshawk and Peregrine Falcon breeding in the Slim Buttes, 

 South Dakota units of the Sioux District (in 1976 and 1925, respectively). 



Previous studies in and near the Carter County, Montana portion of the Sioux District (see 

 Becker 1978, Becker and Sieg 1985, 1987, Sieg and Becker 1990, and Wittenhagen 1992) 

 indicated that several pairs of the five raptor species of special interest nested in the area in recent 

 years. Becker (pers. comm.) provided data on 25 Golden Eagle nest sites, 59 Merlin nest sites, 

 and 40 Prairie Falcon nest sites in use during 1977-1981 (see Appendix 3). As in South Dakota, 

 several of the sites in Montana were used in multiple years. 



Discrepancies between the literature and the 1994 Heritage Program survey in Montana could 

 be the result of several factors, including (1) the date of the survey (June and eariy July) relative 

 to nesting phenology, (2) lack of thorough coverage of the Long Pines, (3) concentration of 

 survey effort on one specific nesting habitat (cliffs), and (4) actual dramatic declines in numbers 

 of nesting pairs of raptors on the Sioux District. Factors 1-3 seem unlikely to account for the low 

 numbers of nesting raptors encountered. First, the survey was conducted when pairs should have 

 been nesting, either with nestlings (Golden Eagle, Prairie Falcon) or eggs (Meriin). Second, 

 many areas were visited in the Chalk Buttes, Ekalaka Hills, and Long Pines where raptors nested 

 previously. Third, although Merlins may have been under-represented as a result of the survey 

 methodology (they nest in pines below cliffs). Golden Eagles and Prairie Falcons should have 

 been detected in greater numbers if they were present. An actual decline in the number of cliff 

 nesting raptors seems a real possibility. Further field work seems warranted, given the lack of 

 coverage in the South Dakota units, the limitations of the 1994 field effort, and the uncertainty 

 of the current status of nesting raptors on Sioux District lands in general. If time is a constraint 

 for survey efforts, helicopter or fixed-wing aircraft may be used effectively to assess the presence 

 of Golden Eagles and Prairie Falcons (for example, see Call 1978). These two species nest in 

 similar sites on the Sioux District (see species accounts). 



The species accounts that follow are presented as summaries, and include data on nesting 

 habitat, nest site specifications, and nesting success gleaned from the literature (see 

 Bibliography). Heritage Program rank Global (G) and State (S) codes range from 1 (critically 

 imperiled) to 5 (demonstrably secure, though possibly rare in parts of its range). Other codes are 

 B (breeding occurrences), N (non-breeding occurrences for migratory species), Z (ranking not 

 applicable), and X (believed to be extinct, historical records only). 



