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<br />they can tolerate disturbance was not reported. <br />Historically,. their populations declined in Colorado due to <br />two factors: (1) human settlement on the nesting grounds, <br />and (2) people shooting the birds for food. Regarding the <br />latter point, the birds cannot tolerate more than a 5-10% <br />harvest, since they only produce two eggs per nest and a <br />given pair usually only raises one chick per season." The <br />cranes historically nested west of the Continental Divide as <br />far south as the San Juan Mountains in Colorado. When the <br />crane population reaches 115 pairs in Colorado, compared to <br />76 pairs known in 1978, it can most likely be removed from <br />the endangered list. <br />A description of crane activity in Routt County's California <br />Park and Hahn's Peak Basin is quoted from Bieniasz (1979): <br />"Cranes nested along small, willow-lined <br />drainages, usually one pair to a drainage. Nest <br />sites are commonly separated by the ridges that <br />parallel the streams. Larger drainages generally <br />had several pairs nesting along their lengths. <br />Nests were always within 1 m of slow moving water <br />and were surrounded by dense cover, generally <br />willow. The willows provided excellent cover for <br />the nest site after they leafed out in late May. <br />Water depths near the nest ranged from 15 to 16 cm. <br />Nests were composed of willow twigs, mainly <br />obtained from beaver cuttings, and some grass, with <br />the degree of construction varying from pair to <br />• pair. <br />A total of 19 nests were located in 7976 and 1977 <br />in the California Park and Hahn's Peak Basin areas. <br />One nest was used both years. <br />In 1976 hatching success was calculated to be 30.4 <br />percent with chick mortality lowering the survival <br />rate of chicks to 21.7 percent. In 1977 the mean <br />clutch size was 1.94 with a hatching success of 33 <br />percent and a chick survival rate of 25 percent. <br />3 <br />