Pilot Test of Programmatic Approach to
Monitoring Winter Conditions and Trends of
Wildlife Populations and Habitats
in Off-Highway Vehicle Use Areas
First Winter Pilot Test
Winter 2002-2003
Final Report
March 20, 2004
Architects
Principal Investigator
Patricia N. Manley, Pacific Southwest Research Station, USDA Forest Service, Davis, CA 95616
Research Assistants
Joshua P. Stumpf, Lake Tahoe Basin Management Unit, South Lake Tahoe, CA 96150
Wesley B. Davis, Lake Tahoe Basin Management Unit, South Lake Tahoe, CA 96150
Collaborators
Diana Craig, Regional Wildlife Ecologist, Pacific Southwest Region, USDA Forest Service,
Vallejo, CA, 94592
Kathy Mick, Regional Trails Coordinator, Pacific Southwest Region, USDA Forest Service,
Vallejo, CA, 94592
Introduction
Programmatic Monitoring Approach
The purpose of this pilot project was to monitor the effects of Over-Snow Vehicles (OSV) on
wildlife populations and habitats in the Lake Tahoe Basin, California and Nevada. Direct effects
of OSV use include snow compaction, vegetation damage, noise, and physical presence -- a
combination that can negatively affect a wide array of species, from primary producers through
top predators. OSV use in California is growing along with the increasing population of the state
and increasing popularity of winter recreation. The gaps in available information regarding the
effects of OSV use on populations, communities and habitat conditions have thus far presented a
barrier to informed OSV use management. This is particularly true in California where the
number of species of concern in the State is second highest in the United States, following
Hawaii. In the absence informed management, OSV use has the potential to endanger the
survival of some species.
1
This pilot was the first attempt to design and test winter monitoring at OHV use sites. Limited
funding and personnel resulted in the a short field season. Literature review and protocol
development were conducted from November through February, and field work was conducted
primarily in March and April. Given the limited field season, not all proposed protocols were
field tested, and conclusions from the field work are limited to logistics and techniques.
Review of Over-Snow Vehicle Effects on Wildlife
Research on the environmental impacts of over-snow vehicles has increased over the past three
decades, and although many good syntheses are available (e.g. Bury, 1978; Boyle and Sampson,
1985; Gutzwiller, 1991; Knight and Gutzwiller, 1995), many questions remain to be addressed.
Studies on overall ecological impacts have focused primarily on effects resulting from the snow
compaction caused by snowmobiles. Neumann and Merriam (1972) reported extreme alterations
in the temperature profile and thermal conductivity of the snow, increases in water holding
capacity, increased snow melting times, and the formation of a partial gas seal over the substrate.
Keddy et al. (1979) reported similar findings, and noted that approximately 80% of the total
compaction and resulting increase in snow density occurred with the first pass over fresh snow,
making single passes interspersed with snowfall potentially more destructive than multiple
passes on a single day. It is important to note, however, that these effects were not nearly as
pronounced on older, icier snow. This and previous studies (Walejko et al., 1973; Foresman et
al., 1976; Ryerson et al., 1977) also reported significant impacts on subnivean vegetation,
including reductions in standing crop, retarded spring recovery and growth, and significant
damage to supranivean vegetation.
Studies on the effects of snow compaction on wildlife are few. Schmid (1972) reported high
rates of mortality for subnivean fauna in snowmobile use areas and Bury (1978) elucidated that
these effects varied considerably according to snow depth and moisture content. In a review,
Pruitt (1984) further posited that compaction may present a mechanical barrier for subnivean
mammals because of prohibitively high energetic costs of burrowing through the denser medium.
Other studies have reported some groups of animals, such as canids, preferentially using
compacted supranivean trails, presumably because of greater ease of travel. Others, such as
lagomorphs, avoid the same trails in order to avoid predators (Neumann and Merriam, 1972).
Harassment and disturbance from snowmobile generated noise and human presence has potential
direct impacts on wildlife that have drawn much study. For example, early laboratory research
on rodents indicated that while habituation to loud noise could take place after repeated
exposure, it served only to decrease the severity of the stress response, rather than to alleviate it
altogether (Hoffman and Searle, 1967). Subsequent field studies reported home range shifts, and
alterations in movement patterns, reproductive success, escape response, and physiological states
in response to road use (Trombulak and Frissell, 2000). Increases in stress can then precipitate
behavioral changes such as movement patterns, foraging behavior and site abandonment.
Ultimately, changes in the abundance, distribution, and composition of species may occur
(Knight and Cole, 1991), as species sensitive to disturbance may avoid areas where human
activity is common (Miller et al., 1998).
2
The issue drawing the most study by far, however, is the impacts of the roads themselves on the
ecological units they traverse. Roads interrupt landscape patterns, fragment habitat and create
edge habitats, which can inhibit important interior species (Foreman and Alexander, 1998;
Trombulak and Frissell, 2000) and affect species composition and abundance in areas adjacent to
roads and trails (Miller et al., 1998).
Although a large body of work currently exists, many questions remain to be addressed. Studies
addressing the effects of compaction (i.e. Neumann and Merriam, 1972; Walejko et al., 1973;
Foresman et al., 1976; Ryerson et al., 1977; Keddy et al., 1979) have thus far failed to address or
have been unclear about the effects of compaction throughout the snow profile. In particular, it
is unclear if the effects of compaction extend into the depth hoar when the snow deepens through
the season, or if lower layers can still offer some insulation when the upper layers become
compacted. If this is the case, then simply increasing the minimum allowable depth of snow for
snowmobilling could offer protection for subnivean fauna and habitats while continuing to allow
use in impacted areas.
Effects on forest carnivores, particularly those of interest in the Lake Tahoe basin, have thus far
been inferred from reviews of the literature, rather than being directly studied or monitored.
Robitaille and Aubry (2000) found densities of marten tracks significantly higher away from
roads than on them, and several authors (i.e. Neumann and Merriam, 1972; Bury, 1978) have
reasoned that compaction and resultant mortality of small mammals could lead to declines in
predator populations. However, direct links between snowmobile use and changes in predator
populations or behavior has yet to be shown by direct study.
Information concerning the mortality of subnivean mammals is also largely lacking. All authors
reviewed in this paper based their inferences about the mortality of subnivean small mammals
resulting from compaction from a single study conducted by Schmid (1972). The results from
said study, however, were based on a sample of 39 captured mammals in which none of the 21
marked animals were recovered from the experimental plot, while 8 of 18 were recovered from
the control plot. This experiment has yet to be repeated in a variety of snow conditions, thus it is
unclear if these conclusions can be extended to other areas and through varying temporal scales.
Effects on large mammals and birds remain uncertain. Raised stress levels, shifted movement
patterns, and varying degrees of flush responses in response to disturbance were documented in a
variety of animals (Dorrance et al., 1975; Holmes et al., 1993; Creel et al., 2002). It is still
unclear, however, if any of these effects have acute or long-term deleterious effects on
individuals or populations. Certainly, disturbances associated with snowmobiles can negatively
influence an animal’s ability to both retrieve food and conserve energy (McCool, 1978), Thus,
additional study of direct and indirect impacts over short and long time periods is warranted.
In the winter, OSV use has the potential to stress species and the condition of their habitats
through use (physical presence and collisions) and associated compaction and noise (Figure 1).
The presence of roads, regardless of whether or not they are used, can also have effects on
wildlife movement and habitat use (Figure 2).
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Monitoring and Research Hypotheses
The basic interactions depicted in Figures 1 and 2 led to the generation of the following
monitoring hypotheses for compaction, presence, and noise effects.
Compaction
Ho1: Compaction resulting from snowmobile use in meadows does not affect the presence,
abundance, and productivity of resident plant and small mammal species during the winter and
following snow melt compared to meadows not used by snowmobiles
Ha: Plant and small mammal populations are reduced in richness, abundance, and
productivity in meadows with snowmobile use, and impacts are greater with greater
compaction, compared to meadows not used by snowmobiles
ƒ reduced richness of plant species and reduced vigor, cover, biomass, and
productivity of plant species
ƒ delayed vegetative growth and flowering
ƒ reduced amount of available foraging habitat
ƒ reduced population sizes of plants and small mammals during the winter and
following spring and summer
Ho2: Compaction on snowmobile routes in forested habitats does not affect the movement
patterns of subnivean small mammals (i.e., create a barrier to movement) compared to forested
areas not used by snowmobiles
Ha: Subnivean small mammals cross snowmobile routes (above and below snow) less
often than expected based on movements in non-use forested areas, resulting in
fragmentation of populations for the duration of the snow pack
Presence
Ho1: The extent and intensity of use by snowmobiles (e.g., number of snowmobiles per hour,
average number of snowmobiles per day) do not affect the presence or abundance of plant or
vertebrate animal species during the winter and the following spring/summer season
Ha: Increased extent and intensity of use by snowmobiles have a negative effect on the
presence or abundance of plant or vertebrate animal species
Noise
Ho: The level of noise (average per hour and average per day) in use areas does not affect the
occupancy, use, and physiological stress of bird and mammal species.
Ha: The level of noise in use areas has a negative effect on the occupancy, use and
physiological stress of bird and mammal species
The effects of OSV on wildlife populations and habitat conditions in the winter are not well
studied. As a result, the design and assessment of a programmatic monitoring approach
inherently must adopt a number of untested assumptions and associated uncertainties. Research
4
questions are posed below that, if answered, would test a number of key assumptions that have a
high degree of uncertainty.
Compaction
Ho1: Snow depth (or grooming) at the time of first use does not affect the degree or depth of
compaction in the snow base
Ha: Greater snow depth at time of first use decreases the degree of compaction in the
snow base, thus increasing the ability of subnivean fauna to move through compacted
areas and decreasing the impact on ground vegetation.
Ha: Decreases in snow depth following first use can increase the degree and depth of
compaction.
Ho2: Different types of uses use (cross-country skiers/snow shoers, snowmobile, grooming)
have a similar compaction result per snow depth.
Ha: Motorized use results in greater compaction and associated impacts compared to
non-motorized use.
Ha: Motorized use results in greater compaction and associated impacts with fewer
passes compared to non-motorized use.
Ho3: Compaction in meadows from snowmobile use does not affect the thermal conductivity of
the snow pack
Ha: Compaction in meadows from snowmobile use increases the thermal conductivity of
the snow pack, resulting in colder temperatures compared to non-compacted snow
1. Ho1 :Find a bare patch of ground and then be prepared to test different depths of snow
during and after snowfall. Ideally, one would make snow (from machine) and deposit it
at specific depths and then drive a snowmobile across it some number of times and then
measure the compaction, including thermal conductivity (if possible).
Use
Ho1: The presence of motorized vehicles has no greater effect on the presence or abundance of
plant or vertebrate animal species than non-motorized use, and use areas do not differ in the
abundance of supranivean plant or vertebrate animal species compared to non-use areas
Ha: The presence of motorized vehicles has a negative effect on the presence or
abundance of supranivean plant or vertebrate animal species compared to non-motorized
use and non-use areas.
Ho2: Motorized vehicles have no greater effect on the flush response of bird and mammal
species compared to non-motorized use
Ha: Motorized vehicles have a greater effect on the flush response of bird and mammal
species (longer period of time to return to area) compared to non-motorized use
5
Pilot Test Objectives
The OHV WHPP monitoring program is designed to provide information about: 1) condition and
use on all OHV use areas; and 2) the effects of OHV use on plants and animals of concern and
interest.
The pilot test was intended to (1) develop a technique for building a sampling frame, (2) evaluate
response design options, and (3) develop and test field data collection protocols. This
information will be used to develop a draft programmatic winter OHV monitoring plan.
1. Build a sampling frame
We developed a map of snowmobile use by classes, for the study area. Maps need to identify
relative use of various areas (none, low, moderate, high). A measure of use that any forest can
map and use to create use classes needs to be identified.
2. Develop response designs
The response design for each set of taxa (e.g., plants, birds, small mammals) entails establishing
sample sites within each cell, and then conducting data collection at these sites. Sample sites
within each cell were identified using the prescribed process to determine if it is effective.
3. Develop and Test Field Protocols
The full array of field protocols were tested at use and non-use sites in both meadow and forest
ecosystems.
4. Refine the Winter Monitoring Plan
The results of the pilot were used to draft a full programmatic winter OHV monitoring plan.
Study Area
The pilot test was conducted in the Lake Tahoe basin on the LTBMU in 2003. The Lake Tahoe
basin is located in California and Nevada (Figure 3). The majority of the basin, approximately
80% of the 88,000 ha land area, is occupied by National Forest System lands as part of the Lake
Tahoe Basin Management Unit. The basin is bounded by the Sierra Nevada and Carson Ranges,
and encompasses an elevational range from 6229ft to 10881ft (1894 m to 3308 m ). Based on a
review of the primary sources of data for the basin, Manley et al. (2000) determined that 312
vertebrates and 1077 vascular plants occur in the Lake Tahoe basin. The vertebrates consist of
217 birds and 59 mammals, with the remainder consisting of amphibians (n = 5), reptiles (n = 8),
and fish (n = 23).
6
One pair of meadow sites (use and non-use) and one pair of forest sites were selected for study.
Blue Lake meadow was selected as the use meadow site as it is open to both commercial and
private use throughout the winter. Additionally, information obtained from both OHV
personnel and our own preliminary recognizance indicates that this area receives some of the
highest use in the Tahoe area. This site was paired with the non-use meadow on the northwest
portion of Fallen Leaf Lake, as it shares a similar aspect and elevation with Blue Lake meadow
but receives little to no recreational use. A forested area west of Brockway summit was chosen
as the forest use site as two snowmobile tour companies use it heavily. It was paired with a nonuse forest in an area adjacent to the Bayview campground, north of Cascade Lake. This area
shares a similar slope, aspect, and elevation with the Brockway summit area but is closed to
snowmobile use.
Methods
Each topic area in the methods section has two segments. The first segment describes the
proposed methods as of January 2003, and the second segment describes what this winter pilot
effort was able to test with the time, funding, and personnel available. In all cases, tests were
directed at the subset of the proposed methods for which we had the greatest uncertainty
regarding their feasibility and effectiveness.
Sampling Design
Proposed Protocol
Programmatic OHV monitoring sites are proposed to be established using a systematic sampling
frame consisting of 25 ha (500mx500m) square grid cells. These grid cells are large enough to
encompass the response design of all biotic sampling proposed at each use and non-use site.
Summer and winter use sites need to be selected through a separate but coordinated process,
given that summer and winter use sites overlap but are not entirely coincident. In the winter use
season, each cell is classified into one of the following categories: known use (KU) (including
all known snowmobile use areas), potential use (PU) (adjacent or touching known use cells) and
non-use (NU). KU ‘patches’ are identified, consisting of adjacent (and touching) KU cells.
Ideally, all KU cells are monitored, but given financial limitations; the program will sample a
subset of KU cells per Forest. Each cell is also classified in terms of summer OHV use. The
sample of KU cells consists of a mix of cells with summer and winter only use. Cells are
selected through a random process that distributes cells among patches to the greatest extent
possible. For each KU cell selected for monitoring, the nearest NU cell is selected be monitored
concurrently as an index site. NU cells selected as index sites must have the same summer use
classification as their paired KU cell. A small sample of PU cells is selected to document the
frequency and extent of non-designated use.
A subset of the KU cells selected for habitat and use monitoring (and their index cells) is
selected for monitoring biological diversity. Multiple species monitoring protocols are
conducted in these biodiversity monitoring cells, including a minimum of point counts, box live
7
traps, vertebrate area searches (terrestrial and aquatic), and camera stations. Closed trackplates
may also be effectively employed. These techniques are also identified as core protocols for
summer OHV monitoring.
Finally, additional KU cells with known occupancy of species of high concern (SHC) are
selected for monitoring to increase the sample of monitoring sites for these species (assuming
that some biodiversity monitoring cells are occupied by these species of concern and thus also
serve as SHC cells for those species). The number of SHC cells needed to satisfy information
needs for each species of concern varies by species and available funding.
A hexagonal sample area of 10.4 ha (200 m per side) serves as the basis for most sampling
within the sample unit for both the winter and summer season (Figure 4). This fixed response
design will be used for sampling within each sample unit regardless of the type of habitat. The
hexagon can be moved within the cell to be centered on a route in the sample unit (but must
remain entirely within the sample unit). In forested habitats, the hexagon will be rotated so that
the route runs across the center of the hexagon perpendicular to the longitudinal center transect
line that bisects the hexagon into a left and right half.
Pilot Test
We identified winter OSV use areas within the LTBMU and assigned level of use ratings to each
winter use area based on designated snowmobile use areas on the National Forest and local
knowledge (Appendix 1 and 2). Local knowledge was garnered through meeting with winter
OHV law enforcement personnel and through a workshop where USFS employees were asked to
contribute their knowledge about the intensity of different types of winter uses throughout the
basin. This effort served to evaluate the availability of reliable information for identifying use
areas and their relative levels of use. In addition, we selected one meadow and one forest KU
and NU cell were selected for testing field methods. Ideally, we would have replicates of these
meadows and forest sites– two or three in each use class, but limited field personnel and a short
field season precluded the establishment of replicates. Thus, results from the 2003 pilot focused
on questions pertaining to logistics and sampling techniques.
Small Mammal Trapping
Proposed Protocol
Sherman live traps are deployed in grid located in the center of the hexagon (Fig. 1). A trap grid
measuring 90 m wide and 195 m long (7 x 14 traps spaced 15 m apart) is located in the center of
the hexagon (n = 98 traps). The trap grid is oriented such that the long dimension of the grid was
oriented top to bottom in the hexagon, thus the grid straddles the snowmobile route when located
in forested environments. Extra large Sherman traps (4”x4.5”x15”) are used to improve trap
success for squirrels and increase survival rates for all captures.
Traps are placed within two meters of the intended location at habitat features such as logs,
burrows, the base of trees, runways and, always, in areas that provide cover from weather. Traps
are placed at ground level into 21-inch (53 cm) diameter snow pits. A semi-conical lid, 21 inches
8
in diameter, 20 inches high and fashioned from #30 roofing paper is then be placed above the
trap and covered with 15 cm of snow. Trap locations are then marked and uniquely numbered
1.5 m above snow level, either on a tree or 1.5 m wooden stake. All traps are set, opened and
baited in the afternoon of the first day, and checked two times daily (early morning to be
completed by 9 am, and evening to be completed before sunset) starting on the morning of the
second day for 3 consecutive days. Traps are checked and removed during the last trap check on
the afternoon of the fourth day. Observers check off a box for each trap checked to ensure that
no traps are missed during any given check.
Sherman traps are baited with a mixture of rolled oats, birdseed with sunflower seeds, peanut
butter, and small mealworms (approx. 3 cm in length) to provide a high-energy food source to
shrews. Mealworms are frozen prior to use in order for them to remain inside traps after being
baited. Bait for Sherman traps contain approximately one part oatmeal to one part birdseed.
One-half cup of peanut butter and approximately 900 mealworms are mixed together with 2
gallons of oat/seed mix. Polystyrene batting is placed in every Sherman trap to provide warmth.
Traps are re-baited as necessary and mealworms added separately where needed to ensure
availability to shrews.
Individual animals are identified to species, sexed, aged (as juveniles or adults), weighed, and
marked by cutting a patch of hair near the base of the tail before being released. In forested
habitats, animals from opposite sides of the road are marked on opposing sides of the rump to
assess movement across the road (left side of road = left side of tail). Additional information is
be recorded for uncertain species identifications including relevant body measurements such as
hindfoot length, ear length, tail length and head/body length in order to discern similar species
within the genera Tamias, Peromyscus, Microtus, and Sorex.
All traps are cleaned and disinfected after the survey was completed at each point. Traps are
emptied of all loose bait, organic material and polystyrene batting before being placed into a
mild bleach/water solution (approx. 2 cups of bleach to 30 gallons water) where they remain for
a minimum of 5 minutes before being scrubbed and rinsed with clean water.
Equipment needed: 98 extra large (4”x4.5”x15”) Sherman traps (plus a few extra traps), clip
board, trap bait (oat/seed, peanut butter, and mealworms), polystyrene batting (about 2 inch
diameter piece per trap per point), 1 gallon plastic bags (Ziploc bags preferred), scales up to 1000
grams, field rulers, small scissors, mammal field guides or keys, rubber gloves, backpacks for
carrying traps (one per transect), hand lens (shrew identification). Equipment clean-up requires
two 30-gallon garbage cans, water supply, bleach, hose with nozzle, scrub brush, protective
eyewear and a large flat area to spread out traps while drying.
Pilot Test
For the pilot effort, live trapping began mid-March (approximately March 10th). Trapping was
conducted at the non-use meadow site and the use forest site following the proposed sampling
protocol describe above. In addition to the large traps, Sherman long traps were co-located with
every other large trap along the center transect line (400 m line), for an additional 13 traps. The
size of the trap was recorded and the type of bait determined for every capture.
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Baited Camera Stations
Proposed Protocol
Three baited camera stations are established in each sample unit (Figure 4). One camera station
is located 100 m away in a random direction. The two remaining camera stations are set 250 m
from the center of the sample unit in opposing quadrants of the sample unit (100 m from the
corner of the sample unit) at either 45˚ and 225˚ or 135˚ and 315˚ azimuths, to be determined at
random.
Trailmaster TM-550 passive infrared trail monitor cameras are used at camera stations,
consisting of a 35mm Cannon Sureshot A1 camera in conjunction with a Trail Master TM550
passive infrared detector, are set within each sample unit. Each camera is loaded with ISO 400
film and a flash is used for the duration of the survey. The first is set 100 m from the center
point of the sample unit on a random azimuth. Two cameras (the center and one of the corners)
are baited with a mixture of raw chicken, anchovy paste, strawberry jelly and carrots, while the
third is baited with chicken alone. Bait is placed approximately 0.5 meters from the snow
surface; two stations are baited with chicken, strawberry jelly, and anchovy paste in a wire
basket and carrots placed around the tree base; the third station is baited with chicken only.
Camera stations are checked once per week for two weeks (14 days). A 10 x 15 cm note card
displaying the station number is placed above the bait and attached to the tree with pushpins or
22-gauge wire. Camera stations are active immediately after station setup, verified by a test shot,
and recorded events 24-hours a day for 28 days, being checked a minimum of once per week.
Film is replaced any time 18 exposures or more are recorded on any given visit. Bait is replaced
if it is absent or as the observer deems necessary.
Equipment needed: Camera stations: 3 cameras, 3 Trail Masters, 6 wires, 100 feet of 22 gauge
bailing wire, 3 4x6 note cards, permanent marker, 8-12 pushpins, 3 chicken wire baskets, 6 half
chickens, 3 rolls ISO 400 35mm film, necessary batteries.
Pilot Test
The proposed sampling protocol was implemented at all four sample units starting in mid-March
and finishing in mid-April. Half-way through the sample period at each site, gusto was added
within 3 meters of the bait at all stations and cameras.
Bird and Mammal Surveys
Proposed Protocol
Bird and mammal occurrence is recorded along snow track transects (1.8 km transect) that zigzag across the hexagon. Observers walk the transect at a pace of approximately 2 km/hour,
recording the distance, direction, sex, and pertinent behavioral information for all vertebrate
species detected. Flyovers are recorded as such. In addition, observers stop at each of 7 point
10
count stations (as per the summer sampling design) and conduct a 10 minute point count. Six of
the point count stations are located at the points of the hexagon, and one is located in the center.
In establishing the hexagon and associated point count stations, if any count station falls in
dangerous, extremely noisy, or otherwise unsuitable terrain (e.g., on cliffs, near loud creeks or
rivers, in lakes), the station is relocated to the nearest suitable location in a direction away from
other stations, maintaining a 200m minimum distance between stations.
Point counts and transects are surveyed once per month. All count stations associated with a
given point are surveyed on the same day, starting at fifteen minutes after sunrise and finishing
no later than 4 hours after sunrise. Counts last 10 minutes, with data recorded in 3 time intervals:
the first 3 minutes, the next 2 minutes, and the final 5 minutes and 3 distance intervals: 0-50m,
51-100m, and > 100m. Counts are not conducted if precipitation is occurring or if the wind is
greater than a slight breeze (leaves and small twigs moving). Fly-over detections are assigned to
the area outside 100m in density calculations. All individuals detected at each count station are
recorded even if they are detected at another count station during the same morning. Additional
information recorded includes the following: date, cloud cover, wind conditions, observer, start
time, and any notable events or conditions including incidental sightings of non-target species.
Pilot Test
The bird and mammal sampling protocol was developed, but not tested, during the winter 2003
pilot season
Snow Tracking Transects
Proposed Protocol
Track transects are 1.8 km long and situated within the 200 m hexagon. Beginning on an outside
edge of the hexagon, the transect is shaped as follows: 200 m at 180˚, 100 m at 120˚, 300 m at 0˚,
100 m at 60˚, 400 m at 180˚, 100 m at 60˚, 300 m at 0˚, 100 m at 120˚ and 200 m at 180˚ (Figure
4). Starting points are selected at random each week, and the transect is walked in a clockwise
direction on snowshoes. Transects are walked twice per month in each sample unit, ideally
within 24-72 hours after fresh snowfall. Tracks intersecting the transect are measured,
photographed and identified to species where possible. Tracks of larger, focal carnivores
(marten, bear, bobcats or mountain lions) are also followed in an attempt to discover den sites.
Other sign of vertebrate activity is also noted, such as scat, feeding, subnivean access, and
plucking perches.
Equipment needed includes snowshoes (one pair per observer), mammal track guide or key.
Pilot Test
All four sites were sampled once in late March following the proposed protocol.
11
Subnivean Animal Tunnel Counts
Proposed Protocol
Observers walk the mammal trap lines (seven parallel lines 195 m long, 15 m apart) within the
non-use meadow sample unit, counting each visible animal tunnel complex (soil and/or
vegetation casting), nest or seed cache intersecting the transect line. The width of each tunnel is
measured in millimeters and each tunnel is classified as being open and consisting mainly of
vegetation or closed-topped, consisting mainly of soil. Open, vegetative tunnels are made by one
of the two species of voles (Microtus montanus and M. longicautus), whereas closed, soil based
tunnels are made by mountain pocket gophers (Thomomys monticola) (Halfpenny, 1986).
Transects are conducted within a week of the first complete snowmelt within a sample unit.
Pilot Test
The proposed protocol was conducted at one non-use meadow and one use forest site.
Supranivean Vegetation Damage Transects
Proposed Protocol
A variable-area transect method (Parker 1979; Krebs 1999) is used to estimate the density of
damaged woody supranivean vegetation in relation to the overall density of supranivean
vegetation (primarily trees). Each sample unit is sampled once per month. Observers walk until
three damaged individuals (trees showing signs of shear stress, missing branches, bark, tops, etc.)
are located within the 20 m fixed-width transect (Figure 5). The distance is then measured along
the transect from the random point to the perpendicular line that projects to the third individual.
A random distance 1-50 m from the endpoint is then selected as the start of the next transect, at
which point the process is repeated. This procedure is then repeated until at least 30 distances
3n − 1
where
are obtained. Density is then estimated from the following formula: Dˆ v =
wΣ(l i )
D̂ =Estimate of population density, n=# of random points, w=width of transect (5 m), and
li =length of transect searched until third organism was found. Variance for the estimate can be
( Dˆ ) 2
obtained from the equation: Variance( Dˆ v ) = v
3n − 2
This procedure is performed simultaneously for all trees (damaged and non-damaged) along the
transect so that a ratio of damaged to non-damaged trees can be obtained.
Pilot Test
The vegetation damage protocol was developed, but not tested, during the winter 2003 pilot
season
12
Motorized and Non-motorized Use Sampling
Temporal use patterns in use areas are monitored using Trafx infrared trail counters with widescope fittings. Within meadow sites, one counter is placed perpendicular to an access road
leading into meadows, at the access point, while the second counter is associated with a random
camera station within the meadow. In forested sites, counters are placed perpendicular to roads
nearest the center of sample units. Counters are left in place for the duration of the winter, being
removed when snowmobiles are no longer in operation within the sample units.
The Off-Highway Vehicle Counter manufactured by TRAFx (Alberta, Canada. Contact Jake
Herrer) is used because of its small size, approximately the size of a large pen, ability to
determine group size, and the analysis software provided. The counter has a range of ten meters,
a minimum event delay of one second and is designed for use along trails and roads.
Pilot Test
The TRAFx counters were set up at the use meadow site and the use forest site. A total of three
were purchased for $2,000 USD. The settings were as follows: IR-1, Period: H, Period Length:
000. The counters were deployed 27 March 2003 at Blue Lakes Road and Brockway Summit.
Two counters were placed at Blue Lakes, one facing into the meadow and another along the road
forming a meadow access point. One counter was placed at Brockway Summit perpendicular to
the road. The counters were in place for a total of 13 days.
Snow Conditions
Proposed Protocol
Snow depth is measured weekly along the snow track transects every 100 meters for a total of 18
measurements. Samples are collected every one hundred meters along the snow track transects
at points offset from the transect in a perpendicular trajectory on a random side (left or right) and
random distance varying from 5 to 15 meters. Depth is measured to the nearest 0.1 cm using an
aluminum snow probe.
Snow compaction is measured as percent water in the snow pack as indicated by a vertical core
sample of snow taken with an Adirondack snow sampling tube. Samples are collected every 100
meters following the same protocol as for snow depth. A total of 18 measurements are taken,
with the location of each measurement recorded on the data sheet. Samples are collected
monthly throughout the winter; from first snowfall until the snow depth is such that a reliable
measurement cannot be obtained.
Pilot Test
Snow depth and compaction protocols were developed, but not tested, as part of this pilot effort.
13
Ground Disturbance
Proposed Protocol
Once per month, the length of the snow tracking transect that traverses disturbed ground from
snowmobiles crossing areas with little or no snow is recorded. The length of the disturbed area
divided by the total length of the transect provides an index of the proportion of the sample unit
with ground disturbance.
Pilot Test
Ground disturbance protocol was developed, but not tested.
Results
Data collection did not begin until early March, which limited the tests that could be conducted.
In addition, snowfall in the Lake Tahoe basin in the winter of 2002-2003 was below normal with
above average temperatures for the month of March, (National Weather Service, 2003), resulting
in a sub-normal snow pack depth for the duration of the pilot study. The below-average snowfall
for the duration of the pilot should be taken into account when considering the success of
proposed protocols and logistics for subsequent seasons of the study. Specific caveats are
discussed in each protocol section below.
Small Mammal Trapping
Fallen Leaf Lake meadow (NU meadow) was sampled March 11-13, 2003 for a total of 294 trap
nights, and Brockway Summit (KU forest) was sampled March 18-21, 2003 for a total of 389
trap nights. Grid installation required a total of 34 and 18 person hours at Fallen Leaf Lake
meadow and Brockway summit, respectively, with approximately 2 to 3 hours spent daily
checking traps. An additional 8 person hours was required to remove the traps, tar paper and
markings from each site on the final day.
Capture rates were low (Table 1). Fallen Leaf Lake meadow yielded a total of seven captures
representing of two species, Tamiasciurus douglasii and Microtus montanus. Brockway Summit
yielded 10 captures representing eight individuals of two species, Microtus logicaudis and
Peromyscus maniculatus. All animals were healthy upon release and no fatalities occurred at
either site.
The walls of the snow pits iced rapidly after digging, usually within 8 hours of being installed,
particularly at the meadow site. In addition, at the meadow site, approximately 40% of the trap
pits became saturated with water as the snow began to melt. Several tunnel castings were also
observed running through trap pits with no captures recorded.
14
Baited Camera Stations
Trailmaster TM550 infrared trail monitor stations were set up on March 17 and March 18 at all
four sites and run for 14 days at each site. In total, 93 detections were identified to species or
genus, with the greatest number of detections at Fallen Leaf lake meadow (n = 76), and the least
at Bayview (n = 2) (Table 2). Fallen leaf and Bayview also showed the highest and lowest
diversity of detections, respectively. The addition of gusto did not seem to affect detections,
with the exception on the common raven detections at Fallen Leaf Lake. Mammal species
diversity as detected with camera stations was the same across all sites.
Snow Tracking
Snow tracking transects were sampled once at all four sites, requiring two to three person hours
per site. Sampling began 19 March 2003 for the forest units and 20 March 2003 in the meadow
units. We received no new snow within the timeframe of the study, so conditions were less than
optimal for tracking, particularly at the meadow sites. Most tracks observed were not
identifiable to species level, but included those of Lepus sp. and Canis sp., as well as those of
unknown squirrels and rodents. Tracks that were identifiable to species level were those of
Ursus americanus and Martes Americana.
Bayview campground site showed the highest diversity, with tracks of all four species noted
above observed. Brockway summit had the second highest diversity of tracks, with Canis sp.
and unknown rodent being reported. Unknown Canids were the only tracks reported at the two
meadow sites.
Subnivean Animal Tunnel Counts
Subnivean animal tunnel counts were conducted within one week of snowmelt at Fallen leaf lake
meadow and Brockway Summit. No tunnels were observed at Brockway summit. At Fallen
Leaf Lake, we detected 590 tunnels, 16 nests and 7 seed caches intersecting the 1470 m of
transect situated along the 7 mammal trapping lines in the center of the sample unit. Widths
were measured for 222 tunnels within the meadow, and each of these were classified as being
open tunnels consisting mainly of vegetation, or closed-top tunnels consisting primarily of soil.
The remaining 348 tunnels were just classified as being open or closed without being measured.
Tunnels were evenly dispersed throughout the meadow area, becoming sparse within the forested
edges. Closed tunnels seemed more abundant in and near forested edges, while open, vegetated
tunnels seemed to be more abundant in open meadow areas in close proximity to water. Four
person hours were required to complete the survey.
Mean tunnel width for open, vegetative tunnels was 41.7 mm (n=127), while mean tunnel width
for the closed soil tunnels was 76.9mm (n = 95) (Figure 6). A Student’s T-test indicated a highly
significant (p < 0.01) difference between the two types, while the overall distribution of widths is
bimodal with some overlap between the two classes.
15
Motorized and Non-motorized Use Sampling
Over a period of 13 days, the TRAFx counter positioned along the access road to Blue Lakes
meadow recorded 698 events, with a mean of 2.3 events per hour for the duration, while the
counter positioned in the center of the meadow recorded 386 events with a mean of 1.5 events
per hour. The one TRAFx counter positioned at Brockway Summit recorded 517 events, with a
mean of 1.2 events per hour (Figures 7, 8, and 9).
Discussion and Recommendations
General Observations
The identification of sample units using an objective process is difficult to accomplish for winter
use sites. The snowmobile use areas are depicted as large polygon areas on small-scale maps,
and use in non-designated areas can be substantial, as is the case in the Lake Tahoe basin.
Sample unit size seemed to be adequate and appropriate for the proposed protocols. It may be
impossible to develop a sampling frame to select sites with known probability of selection, but
the combination of designated use areas and local knowledge appear to be the best option for
identifying use areas. We recommend that sites selected for programmatic monitoring be a
random sample of designated use areas stratified by ecotype (i.e., forest or meadow) and
proximity to populated areas. The selection of paired non-use sites can be informed by not only
the best ecological match, but local knowledge of use in designated non-use areas can help avoid
the problem of motorized use occurring in control sites.
The winter season poses unique logistical challenges to the implementation of monitoring
protocols. This winter pilot was the first attempt to design and test protocols for monitoring
OHV sites. Literature reviews on the potential effects of snowmobiles on wildlife and habitat
conditions, and winter sampling techniques were conducted in the fall. The literature reviews
and contacts with researchers with experience in winter sampling were then used as the basis for
developing the proposed protocols. The remaining five weeks of winter conditions were used to
field test protocols to the extent possible. Information gained from field tests was primarily
limited to an evaluation of the efficacy and feasibility of proposed protocols.
Our general conclusion is that the primary emphasis in the winter season should be on use and
the condition of sites, including motorized and non-motorized use, snow conditions, ground
disturbance, and vegetation conditions. Most wildlife species are difficult to detect during the
winter, thus probability of detection is low, requiring intensive sampling efforts to arrive at a
practical probability of detection. Use of the sites by upper trophic level species (e.g., American
marten, northern goshawk, California or northern spotted owl) logically may be the first target of
wildlife monitoring in the winter, given that their presence or absence is the outcome of a myriad
of factors acting on individuals, including the combined effects of noise, use, and condition
effects on them and their prey. Presence is the target metric for upper trophic level species that
are expected to reside in the area during the winter months. Surveys for lower trophic level
species (e.g., song birds, small mammals) are likely to yield useful information for a few key
species, and may provide additional information for interpreting the potential impacts of OSV
16
use on wildlife at use sites. Surveys for these species are designed to be conducted in the course
of collecting condition data (i.e., bird and small mammal transects), or require little time to
conduct (e.g., post-snowmelt tunnel counts). Thus, the suite of data collection efforts
recommended at the conclusion of the first winter pilot include: snow depth and compaction,
ground disturbance, vegetation damage, intensity of human use by type, snow tracking, bird and
small mammal transects, and baited camera stations.
We recommend dropping small mammal trapping and adding Accipiter surveys. We do not
recommend small mammal trapping be included in the winter monitoring protocols because they
demand many field hours to conduct and yield little information. The potential value of small
mammal trapping is an estimate of abundance of lower trophic level species potentially impacted
by snow mobile use. However, low capture rates result in data that can only be used to generate
a limited species list that can be more economically gained through other protocols. Dawn
acoustical surveys for Accipiters (i.e., northern goshawk, Cooper’s hawk, sharp-shinned hawk)
were not included in this test, but they should be considered and tested as a valuable addition to
the winter protocol in late winter. Given the difficulty in detecting spotted owls (or any owl
species) during the winter where they are resident currently precludes the inclusion of a protocol
to determine their presence during the winter.
Protocol-specific recommendations provided below reflect the need and desire to keep winter
monitoring activities at the level of investment and return that will meet agency information
needs and funding abilities.
Small Mammal Trapping
Sampling late in the season influenced the low capture rates observed at both sites. Densities of
small mammals are likely low in winter as many species enter torpor or hibernation through the
coldest parts of winter, and remaining mammals may abbreviate movement patterns
significantly, in some cases moving only from nests to food caches. As such, traps that are
widely spaced may be less likely to be encountered. Mammals may have also been reluctant to
re-enter areas immediately after the disturbance caused by digging the trap pits in the snow, as
the icing around the pits may have presented a barrier to movement.
Increasing the density of traps in all or part of the trapping grid could potentially increase trap
success by increasing the likelihood that traps within the grid will intersect movement corridors.
Disturbance to the snow pack could also be minimized by setting out “trap chimneys” (1 m tall
closed-ended cylinders) before snowfall begins to create subnivean spaces for the traps without
intense disturbance immediately prior to the trap session. However, the level of effort and
information gained by small mammal trapping during the winter seemed unwarranted relative to
the objectives of the programmatic monitoring program. A compromise might be trap sites
immediately prior to and following snowmelt coupled with subnivean animal tunnel/cache/nest
transects post-snowmelt. This combination of effort at a subset of sites may provide a reliable
index of abundance and use during the winter.
Baited Camera Stations and Snow Tracking Transects
17
The combination of snow tracking and baited camera stations seemed to be highly effective
approach to detecting small and large mammal species at sample sites. While the animals
detected at most sites were the same with both cameras and snow tracking, there were difference
between the two protocols at Bayview campground. In particular, rabbit droppings and tracks as
well as bear tracks were observed in close proximity to camera stations, with no detections being
recorded of either species by the camera. Marten tracks were also observed within the sample
unit, while no marten were detected with the camera stations. Cameras did allow observers to
positively identify Coyote, while Canis tracks were only identifiable to genus. It is therefore
recommended that in subsequent years of the study, both snow tracking and baited camera
stations continue to be employed in conjunction with one another to maximize species detections
and add reliability to species identifications.
We recommend that baited camera stations only be checked once per week to minimize the
intrusion of human scent into the sample area. The cold temperatures, particularly at night, also
seemed to prevent the gusto from forming an effective aerosol. The addition of fish emulsion
and using a greater quantity of gusto, possibly without the addition of lanolin, may alleviate this
problem. It is also of concern that the addition of carrots to the bait may be attracting both
predator and prey to the same location. As snow tracking proved a more effective method of
detecting rabbits, it is therefore recommended that carrots be omitted from the bait mixture in the
future.
Track identifications were hindered by both a lack of fresh snow during the brief sample period,
and lack of in-depth training of personnel. While the crew was trained in the identification of
tracks of larger species (i.e., carnivores), further training could have aided in the identification of
larger rodent species (i.e., Douglas squirrels and gray squirrels) with a greater degree of
certainty. In subsequent years, it is recommended that crews spend a greater portion of earlier
seasons training with experienced snow trackers, and that surveys be limited to 24-72 hours post
fresh snowfall to increase efficiency and aid in identification.
Subnivean Animal Tunnel Counts
Overall, our observations suggest that subnivean tunnel castings can serve as a useful index of
vole and gopher activity during the winter and indicate if OSV use is associated with reduced
abundance or activity. Future surveys of this type could potentially do without measuring
tunnels, simply classifying them as open or closed. Numbers and distribution of tunnels, nests
and caches could then be used as indices of overall abundance and activity within meadow sites.
They are, however, only of use in meadow areas and should be validated in a variety of
environments with concurrent live trapping.
Motorized and Non-motorized Use Sampling
TRAFx counters seem to provide adequate and efficient measures of activity within use areas,
particularly those bisected by roads. TRAFx counters seem to hold the greatest utility along
groomed snowmobile roads, where they can be placed perpendicular to the road and directly
enumerate all vehicle passes within the sampling period. In meadow sites, TRAFx counters are
inadequate to produce a direct enumeration of users throughout the meadow as they only have a
18
range of 10 meters. It does seem that they could be of greater use in meadows if placed on
access roads leading into the meadow. The data obtained could then used to produce an index of
use that could be made comparable between appropriately matched sites. While this seems to be
the least labor-intensive method, a snowmobile count by an observer at comparable and regular
intervals may also prove sufficient. These data may be coupled with commercial outfitter
operation as well as car/trailer counts.
Literature Cited
Boyle, S.A. and F.B. Sampson. 1985. Effects of nonconsumptive recreation on wildlife: a
review. Wildlife Society Bulletin 13:110-116
Bury, R.B. 1978. Impacts of snowmobiles on wildlife. Transactions of the North American
Wildlife and Natural Resources Conference 43:149-156
Creel, S., J.E. Fox, A. Hardy, J. Sands, B. Garrott and R.O. Peterson. 2002. Snowmobile activity
and glucocorticoid stress responses in wolves. Conservation Biology 16(3):809-814
Dorrance, M.J., P.J. Savage and D.E. Huff. 1975. Effects of snowmobiles on white-tailed deer.
Journal of Wildlife Management 39 (3):563-569
Foreman, T.T. and L.E. Alexander. 1998. Roads and their major ecological effects. Annual
Review of Ecology and Systematics 29:207-231
Foresman, C.L., D.K. Ryerson, R.N. Walejko, W.H. Paulson and J.W. Pendleton. 1976. Effect of
snowmobile on bluegrass (Poa pratensis). Journal of Environmental Quality 5 (2):129130
Gutzwiller, K.J. 1991. Assessing recreation impacts on wildlife: the value of design of
experiments. Transactions of the North American Wildlife and Natural Resources
Conference 56:248-255
Hoffman, H.S. and J.L. Searle. 1967. Acoustic and temporal factors in the evocation of startle.
Journal of the Acoustic Society of America 43 (2):269-282
Holmes, T.L., R.L. Knight, L. Stegall and G.R. Craig. 1993. Responses of wintering grassland
raptors to human disturbance. Wildlife Society Bulletin 21:461-468
Keddy, P.A., A.J. Spavold and C.J. Keddy. 1979. Snowmobile impact on old field marsh
vegetation in Nova Scotia, Canada: an experimental study. Environmental Management 3
(5):409-415
Knight, R.L. and D.N. Cole. 1991. Effects of recreational activity on wildlife and wildlands.
Transactions of the North American Wildlife and Natural Resources Conference 56:238247
Knight, R.L. and Gutzwiller, K.J. 1995. Wildlife and Recreationists: Coexistence through
Management and Research. Island Press 372 Pgs.
McCool, S.F. 1978. Snowmobiles, animals, and man: interactions and management issues.
Transactions of the North American Wildlife and Natural Resources Conference 43:149156
Miller, S., R.L. Knight and C.K. Miller. 1998. Influence of recreational trails on breeding bird
communities. Ecological Applications 8(1):162-169
Neumann, P.W. and H.G. Merriam. 1972. Ecological effects of snowmobiles. Canadian FieldNaturalist 86 (3):207-212
Pruitt, W.O., Jr., 1984. Snow and Small Mammals. Carnigie Museum of Natural History Special
Publication 10:1-8
19
Robitaille, J.-F. and K. Aubry. 2000. Occurrence and activity of American martens in relation to
roads and other routes. Acta Theologica 45 (1):137-143
Ryerson, D.K., D.A. Schlough, C.L. Foresman, G.H. Tenpas and J.W. Pendleton. 1977. Effects
of snowmobile traffic on several forage species and winter wheat. Agronomy Journal
69:769-772
Schmid, W.D. 1972. Snowmobile activity, subnivean microclimate and winter mortality of small
mammals. Bulletin of the Ecological Society of America 53 (20):37
Trombulak, S.C. and C.A. Frissell. 2000. Review of ecological effects of roads on terrestrial and
aquatic communities. Conservation Biology 14(1):18-30
Walejko, R.N., J.W. Pendleton, W.H. Paulson, R.E. Rand, G.H. Tenpas and D.A. Schlough.
1973. Effect of snowmobile traffic on alfalfa. Journal of Soil and Water Conservation 28
(6):272-273
20
Tables
Table 1. Number of individuals per small mammal species captured with Sherman live traps at
two sample sites in the Lake Tahoe basin in the winter of 2003. Brockway site was a forested
winter use site, and Fallen Leaf lake was a meadow non-use site.
Site
Species
Peromyscus maniculatus
Tamiasciurus douglasii
Microtus montanus
Microtus longicaudis
Brockway
7
Fallen Leaf
5
2
1
Table 2. Numbers of detections with baited camera stations before and after the addition of gusto
at two motorized use and two non-motorized use sites in the Lake Tahoe Basin in 2003 as part of
the over-snow vehicle pilot monitoring test.
Forest
Meadow
Brockway (use)
Bayview (non-use) Fallen Leaf (non-use) Blue Lakes (use)
Detections
Detections
Detections
Detections
Detections
Detections
Detections
Detections
before
before
before
before
after gusto
after gusto
after gusto
after gusto
gusto
gusto
gusto
gusto
Canis latrans
4
1
1
0
4
0
5
0
Canis familiaris
0
1
0
0
6
0
0
0
Canis sp.
0
0
1
0
0
0
0
0
Peromyscus sp.
0
0
0
0
0
0
2
1
Corvus corax
0
0
0
0
20
42
0
2
Cyanocitta stelleri
0
0
0
0
0
4
0
0
21
Figures
a)
SNOWMOBILE USE
1
Presence of vehicles
and people
Noise
Snow compaction
2
Formation of partial gas seal
over substrate
Crushing of
subnivean mammals
Increased snow density
4
5
3
Increased thermal
conductivity
–> colder temperatures
Delayed snow melt
Reduced soil moisture
Changes in supranivean
movement patterns
Delayed plant growth
Decreased plant abundance,
survival, productivity
Increased physiological stress
and energetic requirements
Reduced plant productivity
and food availability
Decreased plant species
richness, abundance,
survival, productivity
6
Decreased small mammal
abundance, survival,
productivity
22
Changes in distribution
of small mammals
b)
SNOWMOBILE USE
1
2
Snow compaction
Presence of vehicles
and people
5
Noise
Supranivean
vegetation damage
4
Flush response
Increased
physiological stress
Interference with
communication
Woody plant mortality
Injury or mortality from
direct impact
Changes in movement patterns,
foraging behavior,
site occupancy
3
Decreased species richness,
animal abundance,
productivity in use areas
Figure 1. Interaction web for winter OHV use and wildlife and plant populations. a)
interactions associated with snow compaction. b) interactions associated with presence of
vehicles, people, and noise.
23
Roads
Habitat loss and
fragmentation
Increased risk
of predation
Increased risk
of parasitism
Corridors for
movement
Altered movement
patterns
Altered foraging
behavior
Decreased
site occupancy by
native species
Decreased
productivity
Change in
species composition
and abundance
Figure 2. The potential effects of roads on wildlife populations and habitat conditions.
24
Brockway summit
#
Bayview
Campground
#
#
#
Fallen
Leaf
Meadow
#
#
Blue
Lakes
Meadow
N
#
4000
0
#
4000 8000 Meters
Figure 3. Location of 2003 over-snow vehicle pilot test sites on the Lake Tahoe Basin
Management Unit in the Sierra Nevada, California.
25
26
Winter
200 m hex
~12 ha
PC
CS
PC
PC
CS
Road
(KU cell
only)
TP PC
ST
ST
PC
PC
TR
Shermans
Spot map
PC
CS
N
Figure 4. Schematic of winter sampling array within each 500 x 500 m sample unit. CS =
camera station. TR = snow tracking and bird transect (zig-zag line throughout hexagon). PC =
Point count station. ST = Sherman trap grid.
27
L1
L2
w
S ta rt tra n s e c t 1
S ta r t tr a n s e c t 2
Figure 5. Vegetation damage transect for use in winter over-snow vehicle monitoring sample
units.
Figure 6. Distribution of tunnel widths encountered at Fallen Leaf Lake meadow in the Lake
Tahoe basin as per a post-snow melt survey.
29
30
TRAFx REPORT:
Project:
Counter:
BLgroomed
Start:
Finish:
2003-03-27 16:00
2003-04-09 07:00
Location:
Comment:
Mean Hourly
00:00
0.5
01:00
02:00
03:00
04:00
05:00
06:00
07:00
08:00
09:00
10:00
11:00
12:00
13:00
14:00
15:00
16:00
17:00
18:00
19:00
20:00
21:00
22:00
23:00
Total Counts:
Total Periods:
Period Length:
Mean:
Mode:
Median:
Standard Deviation:
Maximum:
Minimum:
Total Weekday:
Total Weekend:
Daily Max/Min Weekday:
Daily Max/Min Weekend:
698
304
1 hour
2.3
0.0
0.0
8.2
97
0
554
144
292 / 4
88 / 6
Daily Mean Weekday:
Daily Mean Weekend:
Mean Monday
Mean Tuesday
Mean Wednesday
Mean Thursday
Mean Friday
Mean Saturday
Mean Sunday
55.4
36.0
149.0
13.0
42.0
50.5
22.5
25.0
47.0
31
0.6
0.5
0.1
0.0
0.0
0.0
3.4
2.0
1.3
1.8
7.3
4.1
3.6
5.0
5.6
2.6
1.0
0.2
0.5
2.8
8.5
3.5
1.2
Figure 7. TRAFIx counter summary of use by hour, Blue Lakes Road, 28 Mar 2003-9 Apr 2003
TRAFx REPORT:
Project:
Counter:
BLmeadow
Start:
Finish:
2003-03-27 16:00
2003-04-07 10:00
Location:
Comment:
Mean Hourly
00:00
0.8
01:00
02:00
03:00
04:00
05:00
06:00
07:00
08:00
09:00
10:00
11:00
12:00
13:00
14:00
15:00
16:00
17:00
18:00
19:00
20:00
21:00
22:00
23:00
Total Counts:
Total Periods:
Period Length:
Mean:
Mode:
Median:
Standard Deviation:
Maximum:
Minimum:
Total Weekday:
386
259
1 hour
1.5
0.0
0.0
9.5
117
0
352
Daily Mean Weekday:
Daily Mean Weekend:
Mean Monday
Mean Tuesday
Mean Wednesday
Mean Thursday
Mean Friday
Mean Saturday
Mean Sunday
44.0
8.5
5.5
12.0
133.0
67.5
30.5
15.5
1.5
32
0.2
0.0
0.1
0.3
0.1
0.0
0.2
0.0
0.7
4.8
13.1
2.9
2.1
1.6
0.4
8.2
0.3
0.2
0.0
0.2
0.4
0.2
0.3
Total Weekend:
Daily Max/Min Weekday:
Daily Max/Min Weekend:
34
133 / 0
20 / 0
Figure 8. TRAFIx counter summary of use by hour, Blue Lakes meadow, 28 Mar 2003-9 Apr 2003
TRAFx REPORT:
Project:
Counter:
brockway
Start:
Finish:
2003-03-28 16:00
2003-04-15 20:00
Location:
Comment:
01:00
02:00
03:00
04:00
05:00
06:00
07:00
08:00
09:00
10:00
11:00
12:00
13:00
14:00
15:00
16:00
17:00
18:00
19:00
20:00
21:00
22:00
23:00
`
Total Counts:
Total Periods:
Period Length:
Mean:
Mode:
Median:
Mean Hourly
00:00
0.1
517
437
1 hour
1.2
0.0
0.0
Daily Mean Weekday:
Daily Mean Weekend:
Mean Monday
Mean Tuesday
Mean Wednesday
Mean Thursday
21.3
40.0
23.7
25.7
25.0
15.5
33
0.0
0.1
0.1
0.2
0.0
0.2
0.2
0.8
0.8
2.2
2.9
4.1
5.8
2.3
2.4
2.2
1.3
1.5
0.2
0.7
0.1
0.2
0.1
Standard Deviation:
2.9
Mean Friday
16.0
Maximum:
29
Mean Saturday
58.3
Minimum:
0
Mean Sunday
21.7
Total Weekday:
277
Total Weekend:
240
Daily Max/Min Weekday:
40 / 0
Daily Max/Min Weekend:
100 / 0
FIVE PEAK PERIODS: 2003-04-05 13:00 (29), 2003-04-05 12:00 (21), 2003-04-10 13:00 (19), 2003-04-11 16:00 (14), 2003-04-05 10:00 (11)
Figure 9. TRAFIx counter summary of use by hour, Brockway summit, 28 Mar 2003-9 Apr 2003
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Appendix 1: Notes from OSV Areas and Relative Use Meeting
February 19, 2003 LTBMU
(Notes from WBD)
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Groomed OSV trails are groomed privately, paid for by outfitters
Sno-mo Hotspots map: return to Mike Kreiling
Blue Lakes: high use meadow
Blackwood: high use meadow
Angora Ridge: High/Med use meadow and forest areas, meadows behind houses (talk to
Vic)
Osgood Swamp: Med use forest
Hope Valley: primarily Blue Lakes
Saxon Creek: med use, a lot of open area, power lines
Golf course: problems with trapping mammals, but is a very high use area
High Meadows: talk to patroller, much private land
Jane Oden: Zephyr cove permits, may be able to help with sno-mo rental, discounted tours?
Melanie Green: water quality, may have info about sno-mo outfitter connections
Christmas Valley: Blitzen Rd. Med/High use, especially weekends, cabins and a strip of FS
land that receives a lot of use
Echo Lake: cross country skis c/o snowmobiles
Sno-Parks: mixture of uses, High use
Taylor Creek: Med use
Page Meadows: High cross country, No snowmobiles
Big Meadow: low cross country use, poached by snomobiles
Spooner Summit: high use groomed trails, med use off of trails in forest and meadows
Ken Wallace: contact re: North Shore snomo assn. 583-0361
Safety Plan, JHA, radio check in with camino/LTB office/patrollers?
Uniforms: Mike St.? (talk to Julie)
How many skiers use groomed sno-mo routes? (Mike Kreiling wants to know)
Night use is common (Derrig, Kreiling)
Trail Master plaque for USDA identification (Susan)
Survey boxes or a card with our contact info at Sno-mo areas?
Attendees: Julie Roth, Ted Thayer, Raul Sanchez, Garrett Villanueva, Mike Kreiling, Don, Vic
Lyon, Shay Childress, Mike Derrig, Wes Davis, Josh Stumpf, , Susan Spaulding
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Appendix 2: Meeting with OSV patroller Tony Glauser
February 20, 2003 LTBMU
Meyers Wildlife Office
*notes are in addition to areas identified on USGS quads by Tony (WBD)
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Grass Lake: low use, non motorized
Blackwood: 4th of July Bowl, high mark, difficult access and parking, medium
snowmobile use
ƒ Sand Pit (twin peaks): highest summer use, bad snowpack, usually avoided by OSV
ƒ Mt Rose: Third Creek drainage heavy snowmobile use, Tahoe Meadow high non-moto
use, wilderness is often poached from Mt. Baldy
ƒ Watson Lake: meadow high use by private riders, lake accessed through commercial
tours (mainly circle lake)
ƒ Angora: meadows low use, urban interface
ƒ Truckee Marsh: closure, low use, STPUD administrative use snomobiles
ƒ Night use: urban interface areas, N.Upper Truckee, Osgood Swamp
ƒ Freel area: closure, poached
ƒ The Dump (Elks Club): closure, poached
ƒ Radio:
1. REC46 – Tony Glauser
2. REC47- Shawn (osv patroller)
19EDWARD2- Bill Johnson (law enforcement)
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