CWMP 2016-2017 Winter Report
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Based on this review, this winter we piloted snow track surveys specifically for American
marten in areas outside of our ongoing transects in order to increase our understanding of
areas currently occupied by marten on both sides of the highway. Based on habitat,
accessibility for observers, and proximity to the interstate, field teams were assigned an
area to survey. During that survey, the team would snowshoe through the area, selecting a
route that was both logistically feasible and attempting to cover as much of the assigned
area as possible. If marten tracks were discovered they were recorded as per observations
for transects. A GPS track was recorded of the survey route to record the actual route
surveyed and keep track of our survey effort.
Four surveys were scheduled for this winter, however only two were completed due to
field conditions and team leader availability. Both completed surveys, carried out south of
the interstate, detected American marten tracks. These limited results suggest a more
robust survey effort could help increase our understanding the occupancy of the study area
by this species. Additionally, volunteers who participated in these two surveys responded
positively to the experience. For numerous volunteers who have been with the project for
many years, providing a novel field objective appears to be a value added experience for
their participation with the project.
In the coming year, we will increase the number of these surveys and focus on locations
west of the pass. East of the pass we have never detected American marten on any of our
transects which are at lower elevation, out of the subalpine habitat the species is strongly
associated with in the Cascades. Having just begun surveying a single site west of the pass
this field season, we currently have no information about presence of American marten
there. Human infrastructure development at Snoqualmie Pass continues to expand. It
currently appears that there may not be any connection between populations of marten
north and south of the pass. It appears likely that there are no marten using the lower
elevation habitat east of the pass. Determining the presence and landscape use by the
species west of the pass is critical for understanding the overall impact of the highway
corridor on this species.
Figure 1 Marten detections from 2017
