WSP00537

• File Number: 8220.112.K
• Description: Dallas Creek Participating Project
• State: CO
• Basin: Gunnison
• Water Division: 4
• Date: 11/16/1979
• Author: USDOI - USFWS
• Title: Biological Opinion for Dallas Creek Project-Colorado
• Water Supply Pro - Doc Type: Biological Opinion

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the 1940's. In Colorado,'only four wild peregrine eyries produced young
in 1979 compared to a historical high of 31 productive sites. As reintroduction
efforts intensify, the last-occupied sites with the history of greatest
use are expected to be the first to be reoccupied. Consequently, it is
crucial for recovery of peregrines that WPRS and other Federal agencies
maintain formerly occupied nesting habitat. .

We do not agree ,with the WPRS's biological assessment that the proposed
project would not impact hunting habitat or affect tbe peregrine falcon.
An adult male peregrine observed in May, 1975, along the Uncompahgre
River near RidgeWay may not have been in migration as the assessment
states but may have nested at Cimarron Ridge. A peregrine eyrie was
discovered there in 1976 ana it fledged one bird that year. The site
was active again in 1977, fledging 'two young. Peregrines were not
observed at .the eyrie in 1978 or 1979; hO>7ever, this does not mean tbe
birds abandoned the area. Breeding peregrines frequently alternate
nesting activities to different ledges on a cliff face or relocate to
adjacent cliff faces. Consequently, the Cimarron Ridge peregrines may
have shifted to another cliff complex in the immediate' vicinity. and have
r~~~;ned undetected.

The eyrie at Cimarron Ridge :is within' 10 miles of the proposed project.
The peregrines we expect to .be nesting along the ridge would hunt the
riparian zone which would be inundated by the proposed project. Peregrines
in Colorado often travel 10 miles from their eyries in search of food;
in Utah, hunting parents have been known to travel up to 17 miles. The
riparian zone which the reservoir would inundate is within hunting range
of the Cimarron Ridge peregrines.' Riparian habitat is a common feature
of many peregrine nesting territories primarily because it supports a
wide diversity of prey. Loss of this habitat would reduce the variety ,
and density of passerine birds and other peregrine prey.

Peregrines require cliffs (200 to 400 meters high) for nesting and
extensive hunting habitat with adequate prey to support them and their
young. Both kinds of habitat exist in the vicinity of the proposed
project. Contrary to the biological assessment, the reservoir would not
create peregrine habitat and would attract few>7aterfowl and shorebirds.
Moreover, waterfowl and shorebirds are not maj or prey for peregrines in
Colorado. Colorado peregrines rely more'on several species of blackbirds
and other passerines associated with riparian zones.

According to the final environmental statement, the propoRed reservoir
would cover 1,030 acres and have a 13.2-mile shoreline. Release of
water for irrigation would reduce the reservoir to 525 acres and 6.2
miles .of shoreline.' The dry -barren flats created by the drawdown >7ould
not benefit peregrines. If cattail marshes and emergent vegetation were
established, prey diversity and availability would increase, thereby
reducing the loss of bunting habitat that the peregrines would experience
because of the reservoir. However, the proposed project would not
create such habitat. In addition, recreational areas and housing developments
addressed in the environmental statement woUld pH~;nate or reduce the
value of an additional 600 or IIlOre acres.