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Page 2 <br />Disturbance (i.e. blasting, drilling, increased traffic, noise, etc.) in the vicinity of a nest does <br />affect eagles to some degree, but it is highly vaziable. Severe disturbance may cause adults to <br />abandon a nesting attempt and severe and/or chronic disturbance may result in nest or territory <br />abandonment. Generally, '/4 - '/z mile buffers encircling a nest and seasonal restrictions are <br />recommended to protect raptors from any type of disturbance. Buffer size may vazy depending <br />upon line-of-sight, intensity of disturbance, and timing of project. <br />For golden eagles, raptor biologists recommend no surface occupancy (beyond that which - - <br />historically occurred in the area) within''/a mile radius of the nest site(s) and seasonal restriction <br />to human encroachment within '/< mile of the nest from December 15 to July 15. Based on these <br />recommendations, we think that impacts to the eagles from the quarry would not be likely. <br />Specific buffers for protecting eagle nests from blasting activities aze not known. Impacts due to <br />disturbance may not be immediately evident. When golden eagles aze disturbed, they may fly <br />mile or more away and perch and watch. This could lead to chilling or overheating of eggs or <br />chicks and starvation of nestlings even though on-site activities did not appeaz to impact the <br />eagles. <br />Although provisions of the MBTA are applicable year-round, most migratory bird nesting <br />activity in eastern Colorado occurs from April 1 to August 15; however, some migratory birds <br />aze known to nest outside of the primazy nesting season. If proposed work is planned during the <br />primary nesting season or at any other time that may result in take of nesting migratory birds, the <br />Service recommends that the project proponent (or construction contractor) arrange to have a <br />qualified biologist conduct a field survey of the affected habitats to determine the presence or <br />absence of nesting migratory birds. It is further recommended that the results of the field <br />surveys for nesting birds and qualifications of the biologist performing the surveys be <br />documented and that information be maintained on file for potential review by the Service (if <br />requested) until construction of the proposed project is complete. The Service's Colorado Field <br />Office should be contacted immediately for further guidance if a field survey identifies the <br />existence of one or more active bird nests that cannot be avoided by the proposed work. <br />