2010-04-06_REVISION - M1979205 (13)

Home Browse Search

BALD EAGLE ADAPTATION TO HUMAN PRESENCE Rifle Bald Eagles The new Rifle Bald Eagle nest is located in the top of a mature cottonwood tree approximately 50-60 above the ground. The vegetation surrounding the nest is composed of a mature cottonwood gallery with an understory of Russian olive, tamarisk and various riparian shrubs and grasses. It is highly likely that this is the same pair of Bald Eagles that occupied the former nest. This pair of Bald Eagles has adapted to and successfully nested in the presence of significant human activity. The former nest site was located approximately 0.14 miles (730 ft) from vehicular traffic on I-70; within 0.25 and 0.50 miles of two active gravel mining operations; within 0.43 mile of the Union Pacific Railroad; within 0.42 miles of the City of Rifle's water treatment facility; and within 0.25 miles of industrial sites south of 1-70. The USFWS National Bald Eagle Management Guidelines indicate that Bald Eagles are unlikely to be disturbed by routine use of roads, homes, and other facilities where such use pre-dates the eagles' successful nesting activity in a given area. It goes on to indicate that in most cases, on- going existing use may proceed with the same intensity with little risk of disturbing Bald Eagles. The new Rifle Bald Eagle nest is located along the south bank of the Colorado River approximately 0.5 miles downstream of the former nest site. However, it is in the presence of similar human disturbance factors with I-70 at 0.23 miles; within 0.67 and 1.0 miles from gravel mining operations; within 0.2 miles of the Union Pacific railroad; 0.23 miles from the City of Rifle's water facility; and 0.33 miles from industrial sites south of I-70. Previous Bald Eagle Nest Monitorine WestWater's biologists have been monitoring four Bald Eagle nests along the Colorado River between Rifle and DeBeque for the past 2 years. This monitoring has provided valuable information regarding Bald Eagle response to human and industrial disturbance factors. Results of this monitoring have shown that Bald Eagles adapt to human activities near nest sites that are well within USFWS and CDOW recommended buffer zones. The following is a summary of observation made during Bald Eagle nest monitoring. 1. Three of the Bald Eagle nest sites are located adjacent to gravel mining operations. At two of the mine sites, Bald Eagles occupied new nest sites while the mines were actively producing gravel. The following is a summary of nests located adjacent to gravel mine sites. • Average distance from edge of mine pit to nest = 776 ft (0.15 mile). The closest is 400 ft and most distant is 1,895 ft. • Average distance of nest to rock crusher = 1,549 ft (0.2.9 mile). • All three gravel-mining operations were active during the 2009 nesting season. All three nests successfully fledged eaglets in 2009. WestWater Engineering 5 3/16/2010