To ()l)tain (luaiititative data con- 

 cerning the o()l(]en eai»le-antelope 

 relationship, two areas in north- 

 central Colorado bounded on the 

 north by the Wyomino; boundary 

 "svere selected as study areas in the 

 spring of 1947. One was the Colo- 

 rado State Antelope Refuge, of ap- 

 pi-oxiniately 114 square miles, and 

 the other an are." of similar size 

 some 14 miles to tl e east. Although 

 the refuge was adi littedly the more 

 suitable for ant^elope, ap})roxi- 

 mately one-half of the other area 

 compared favorably with the refuge 

 in forage, teri-ain, and lack of bar- 

 riers that would inhibit antelope 

 movement. Xest sites and hunting- 

 territories for eagles were about the 

 same on both areas. The principal 

 economic use of each area was graz- 

 ing of sheep and/or cattle. The 

 study on the refuge was conducted 

 cooperatively by the United States 

 Fish and Wildlife Service and the 

 Colorado Game and Fish Dei)art- 

 ment, represented by Biologist 

 Robert R. Elliott, who was con- 

 ducting fawning studies at the time. 



Between June C and 18, 1947. four 

 occupied eagle nests were found on 

 the refuge and two on the area to the 

 east. An aerial survey of the areas 

 at a later date failed to disclose 

 additional nests. The activities of 

 the six pairs of eagles and their 

 young were followed at intervals 

 until October 1(). During the fol- 

 lowing winter, P^lliott maintained 

 records and determined the year- 

 round presence of eagles in the vi- 

 cinity of certain nests on the refuge. 

 In April 1948, the writer again 

 visited each nesting territory to de- 



termine occupancy during the 1948 

 nesting season. 



Tnfoi-mation supplied by the 

 Colorado Game and Fish Depart- 

 ment indicated that approximately 

 548 adult antelope were on the 

 refuge during the 1947 eagle nesting- 

 period. The antelope population on 

 the other area was estimated to be 

 not more than 50. Relatively few 

 white-tailed and black-tailed jack- 

 rabbits or cottontails were ob- 

 served on either area. Two prairie- 

 dog "towns'- of several dozen bur- 

 rows each were located within the 

 radius of influence of one nest on 

 the refuge area and another "town" 

 was within a few hundred yards of 

 one of the nests on the other area. 

 There may have been other undis- 

 covered towns on either or both 

 areas. A scattered population of 

 mide deer was present in suitable 

 habitat on each area. 



In addition to these potential 

 ]n-ey species, each area supported 

 numerous other acceptable food 

 species including small rodents, 

 small mammalian predators, and 

 several species of birds. Scarcity 

 of sign indicated low coyote and 

 bobcat populations, due no doubt to 

 intensive control for several years. 

 Fresh carrion was found on one 

 occasion on each of the areas dur- 

 ing the 1947 nesting season. Eagles 

 were observed feeding on it in the 

 refuge. Although a carcass on the 

 other area gave evidence of having 

 been fed on, none of the large birds 

 was observed feeding on it. 



All golden-eagle nests under study 

 on the two areas were located on 

 rock ledges adjacent to open country 

 iidiabited by antelope. Two nests 



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