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FOREST LIFE
Forest Carnivore Study: Missing
Lynx?
Forest carnivores such as the American
marten, lynx, wolverine, fisher and bobcat reign at the top of the food
chain along with bears and wolves. Because information about their
presence in the North Cascades is limited, park biologists have a vested
interest in the study of these rare and secretive animals. Inventories
relating to these species are part of the plan to document to the 90%
level mammals, birds, reptiles, amphibians, fish and flowering plants
found in the park.
A two-year survey of forest carnivores has
revealed information about their status and distribution in North
Cascades National Park. From late January through mid May of 2003-2004,
biologists and volunteers set up temporary study stations within
carefully chosen areas of the park. Motion-triggered cameras captured
images of animals lured to the sites by scent attractants and
bait.
Spotted Skunk
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Biologists overcame challenges presented by
winter weather and remote study stations - they collected 2,067 color
images of 13 mammal and 5 bird species. Though bobcat, cougar, and
American marten are among the species caught on film, others are
disturbingly absent: the wolf, wolverine, fisher, and lynx were not
detected.
Park biologist, Roger Christophersen, offered
an explanation for these missing links: "We have to remember that
carnivores are very rare, elusive, and generally are far-ranging, making
them very difficult to study". Extreme terrain and winter conditions
made what may have been ideal habitats inaccessible. Roger also added,
"It's possible that some of these species have suffered severely from
habitat alteration, trapping pressure, and maybe even recreational
impacts and have never been able to fully recover (to historic levels)."
Some of these species may be gone from the park or even the
region.
Researchers were also able to compare results
from North Cascades NP with similar carnivore surveys from Mount Rainier
and Olympic National Parks. Interestingly, American marten, a member of
the weasel family, was the most commonly photographed species in North
Cascades and Mount Rainier, but was not seen in Olympic. Also, while
numerous images captured red foxes in Mount Rainier, photos of this
species were absent in the other two parks. Researchers are careful to
point out that some species could be more attracted to the lures than
others, and this could also be true for the same species across
different regions. However, regional differences and the apparent
absence of some species raise important new questions for future
research.
Pine Marten
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Park biologists in North Cascades NP will
continue this investigation with new sites and a change in season. Using
available information on the ideal habitats of the more rare species,
combined with records on where they have been observed in the past,
researchers will focus on promising new study sites. To address the fact
that these sites may be at higher elevations, where terrain and
conditions have been problematic, they are planning to conduct the
survey during the summer months. The heartfelt hope is that at least one
of these elusive animals will smile for the camera.
More Than Just A Pretty Song - Landbird
Inventory
Don't plan on sleeping late during a summer
camping trip in North Cascades National Park. Each dawn breaks with a
concert of birdsong winter wren, Swainson's thrush, olive-sided
flycatcher, and dozens of other songbirds project their voices skyward
to attract mates and defend territories. Some of the singers live here
year-round; others migrate thousands of miles to spend a short breeding
season in the park.
North Cascades encompasses a wide range of
elevations and precipitation gradients which provides a variety of
habitats important to birds. They are the most visible animals in the
North Cascades Ecosystem. The high body temperature of birds, their
rapid metabolism, and their high ecological position in most food webs
make them good indicators of the effects of local and regional changes
in ecosystems. Because birds are fairly abundant and most are active
during the day, it is very feasible to inventory and monitor their
populations.
In 2001 the National Park Service, the
Institute for Bird Populations, and Western Washington University joined
resources to conduct a two-year inventory of terrestrial (land-based)
birds and analyze their distribution across the park. Similar
inventories have been done or are planned for other National Park
Service areas in the Northwest. The North Cascades National Park
inventory was carried out over a broad range of habitats from low
elevation west side Douglas fir forests up to sub-alpine heather meadows
and down to east side lodgepole pine forests. Scientists carefully chose
the sample plots both along and away from trails. Field crews began bird
inventories in the plots right after sunrise and continued for 3.5
hours, identifying and recording all birds heard and seen.
To help understand the food and shelter needs
of birds within each habitat, the crews also recorded details about the
vegetation and other characteristics of the sample plots. They measured
the average height and of vegetation and noted the plant species present
and the aspect of the plot, its slope, and the presence of
water.
Swainson's Thrush
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116 species of birds were detected during this
study. 105 were seen or heard at least once at survey points, while 11
were recorded only during early season training sessions or at other
times of the field season when crews were not conducting inventories.
Perhaps the most profound and thought provoking findings of this work
have to do with the relationship between the number of species detected
and the total number of birds only half the species were detected at
least ten times. A mere five species appear to comprise just over half
of the total number of birds inhabiting the park during the breeding
season. Those species are the pine siskin, chestnut-backed chickadee,
dark-eyed junco, golden-crowned kinglet, and winter wren.
The morning chorus across the park provides
information beyond bird identification. Scientists are analyzing the
inventory data to address several scientific and management questions.
The findings will help determine:
if the diversity of species present varies with
elevation if habitats with more species also support larger numbers of
birds how management decisions, such as removing dead trees or fire
management, affect species diversity and abundance how human activities within the park affect the diversity of bird
species and their total numbers
The concert of bird song doesn't last long in
the North Cascades. By September, the intense and diverse songs have
faded into another season of quiet. However, the data gathered about
these well-traveled wonders helps build our understanding of this
complex ecosystem and will assist land managers in making decisions that
affect future generations of birds.
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