REP49359

• Permit No: M1993041
• IBM Index Class Name: Report
• Doc Name: BLACK-FOOTED FERRET SURVEYS ON THE DOWE FLATS PROJECT AREA BOULDER CNTY COLO
• Media Type: D
• Archive: No

Black-footed Fertet Report

Dowe Flats Project
2. Three searches must be made over the entire prairie dog distribution to be surveyed.
Each search should be done when fresh snow has been present for at least 24 hours and
after 10 or more days have passed since the prior survey period. Ideal survey conditions
occur when 3-6 in. of snow has been on the ground for 2-3 days, with no melting or wind to
erase or deform deposited sign.
' 3. Vehicles driven at < 5 mph may be used to search for ferret tracks or diggings, but
complete, visually overlapping transects of the survey area are required.
The survey area was delineated by circumscribing a 0.5 mile zone around all impact areas
within the permit area. All prairie dog towns within this zone were surveyed by a
t combination of pedestrian and vehicular transects. Survey routes extended beyond this zone
in an attempt to cover all prairie dog habitat in the valley. Vehicular routes were conducted
' just after dawn along County Road 47 (CR 47), limestone ridge, and along the canal road
west of CR 47. Pedestrian transects were conducted by Thompson, Figgs, and Lederer at
' intervals of < 100m. Since ferrets will travel up to 4 miles per day, any ferret in the area
should be detected with transects of this width. Tentative routes were mapped prior to
surveys and each surveyor was issued a map for field use. The entire prairie dog distribution
was divided into survey units and each unit was surveyed by the field crew, generally along
north-south transects. Transects were mapped as they were conducted. All survey personnel
' reviewed Clark et a1. (1983) and USFWS (1989) prior to surveys. Before surveys, Thompson
also lectured other survey crew members on survey procedures, winter ferret life history, and
' sign of ferrets and other wildlife that might be detected.
' 4.3 NOCTURNAL SURVEYS
' Nocturnal ferret surveys were conducted, following USFWS (1989), on August 7-10, 1994
because winter 1993/94 survey conditions were unsuitable for 3 replicated diurnal surveys.
' It was considered far too impractical to clear the entire prairie dog complex of which Dowe
Flats is a part. Therefore only the towns being affected were surveyed in an attempt to
' "clear" the entire prairie dog distribution within Dowe Flats. The rationale was that since
Dowe Flats contained the largest prairie dog town in the local area, any ferrets present in
this general area should have gravitated to this town. If no ferrets are located in Dowe
' Flats, it is even more unlikely that they would occur in any of the small, fragmented towns
in the surrounding area.
Western Ecosystems, Inc. ( November, 1994