CWMP 2016-2017 Winter Report
3
corridor in the Washington Cascades. Ongoing reconstruction by the Washington
Department of Transportation on Interstate 90 east of Snoqualmie Pass has been designed
to improve road safety for motorists and increase the permeability of the road for wildlife.
Field Methods
CCWMP employs trained volunteers to walk transects adjacent to the interstate and track
wildlife. Set transects are monitored three times over the course of the winter on average
and are established at locations where crossing structures either exist and are being
improved or have been targeted for installation. Transects run parallel to the highway
about 150 meters from the roadbed. Field teams document tracks and signs of any mammal
species larger than a snowshoe hare found along the route. At least one set of tracks is
trailed on each transect per visit in an attempt to document the animal's relationship to the
interstate. Observations are photo-documented in the field and all photos are reviewed by
expert observers out of the field to assess observer reliability. All species of high
conservation value are thoroughly documented, including photo-documentation, to ensure
the accuracy of identification.
Results and Discussion
Summary of 2017 Transect Data
This year we recorded 78 observations of six species (coyote, bobcat, elk, American marten,
raccoon, mule deer) across all five transects (Table 1). Most observations were tracks (74).
Non-track observations included one live sighting of an elk at Price Noble South, and elk
marking behavior (4). No Priority One species were detected during our survey period.
Coyote was the primary species found within and across all transects (32 observations; 42
%), followed by bobcat and elk (13 observations each; 17 %). Elk were the second most
common species detected (along with bobcat), even though the snowpack was significantly
higher this year than last. Price Noble continues to have the most detections (31
observations; 39 %) and species (American marten was the only species not detected),
highlighting the importance of the overpass being constructed currently in that area.
American marten was only detected at Snoqualmie Pass, the highest transect of the five,
and only north of the highway. The south transect of Snoqualmie Pass continues to be
depauperate of species with only one coyote observation – highlighting the impact of the
highway and surrounding development on mammal presence.
Table 1. The distribution of species observations across the five transects surveyed during the 2017 monitoring
season.
Transect
Easton Gold Creek Price Noble Snoqualmie Pass
Species
Denny
Creek
N S Both N S Both N S Both N S Both Total
Coyote 7 5 12 4 2 6 5 5 10 3 1* 4 32
Ambiguous 3 1 4 1 1 3 2 5 3 3 13
Bobcat 4 4 2 2 4 1 5 2 2 13
