There I stood on a ridgeline looking down into another
astonishing alpine basin. I had not seen another soul in 3 days, and was feeling
rapture with myself and the wilderness I was hiking through. The snowline
finally had receded enough to allow the glacier lilies, and spring beauties,
then the alpine lupine and Indian paintbrush to flower, which cast a colorful
hue over the lush green meadow that lie in front of me. Aside from the main
trail I had traveled on, the air, the land, and the terrain felt wild. This site
in the Pasayten Wilderness was recommended, along with other areas within the
North Cascades National Park and the Mt. Baker/Snoqulamie Wilderness, because it
is grizzly bear habitat. This area was also described to me as one of the most
remote and intact wilderness regions, not only within Washington, but within the
lower 48. The question that raced through my mind as I looked upon the basin
below was, "where are the North Cascades grizzly bears?"
Grizzly bears are opportunistic animals that roam the
hillsides, looking for the lushest of meadows, the plumpest of berries, and the
best of mates. Males often have homeranges upwards of 400 km2 (150 sq
miles) and female homeranges can be up to 200 km2 (80 sq miles).
Grizzly bears of the North Cascades most likely resemble other interior
populations of brown bears (such as those of the Selkirk mountains), and are
relatively small in size, approximately 150 to 400 lbs, females being smaller
than males. Unlike the 1000 pound coastal brown bears in northern B.C. and
Alaska who feed seasonally on salmon, interior grizzly bears are more dependent
on berries, pine nuts, insects, vegetation, and an occasional winter kill or
scavenged carcass, to accumulate fat reserves. It is necessary to realize how
important fat reserves are for bears. During hibernation, they will lose up to
50% of their body weight, burning a good percent of the fat accumulation they
collected during the summer and fall. They must have enough energy in the
spring, to emerge from their den sites (with or without cubs), and travel to
areas rich in spring forage. Habitat must be able to support the bears by
providing these highfat, nutritious food items.
Based on the availability of food and habitat in the North
Cascades, the Interagency Grizzly Bear Committee
(IGBC) of Washington State has estimated that approximately 200 grizzlies could
inhabit the North Cascade ecosystem.
Although the North Cascade mountains are known for their
steep terrain and jagged peaks, the 16,000 sq. miles of the North Cascade
mountains are bounteous with avalanche chutes blanketed by yellow glacier lilies
(the roots which are excavated by grizzlies for the potato-like corm), subalpine
basins that harbor marmot and ground squirrel refuge (a possible grizzly bear
delicatessen), talus slopes that invite aggregations of alpine army cutworm
moths (a favorite high fat grizzly bear food in Yellowstone National Park), and
alpine meadows are plentiful with huckleberries (a high sugar food source in the
late fall). So again I ask, "where are the grizzlies?"
Grizzly bears are protected as an endangered species in
Washington (USFWS 1981), and classified as sensitive in BC (BC Ministry of
Environment 1995). Despite this protection, they are still struggling to survive
as a small population in the North Cascades ecosystem. Little is known about the
status of the grizzly bears in Washington, and across the border into Canada.
Sitings by biologists, recreationalists, and hunters have identified grizzly
bears, tracks, excavations (large areas dug up for food), and cache sites (large
areas where food is buried for later consumption). There have been 107 confirmed
sitings between 1986 and 1999 based on evidence described to fit the
characteristics of a grizzly bear. Although this information is important, the
documentation does not help us understand, nor help recover the small population
of grizzly bears that still may exist in the North Cascades.
Baseline data is needed. How many grizzly bears exist in the
North Cascades, if any? How many female grizzly bears are in the North Cascades,
and are they producing offspring? What is limiting the growth of the grizzly
bear population? Could it be the lack of food, the lack of females, or possibly
that cubs are not surviving to reproduce on their own? Any or all of these
factors may be holding the grizzly bears of the North Cascades at very low
population numbers; they could go extinct at any time. My studies are using DNA
hair-sampling methods to address some of these questions.
Conservation Genetics
and DNA sampling techniques are
relatively new in wildlife management and their applications are diverse. In
Japan, DNA studies are being used to identify threatened and endangered whale
species sold as meat products in the marketplace. While similar studies to my
own include genetic work on Andean Spectacle bears, wolverines, and lynx. The
idea of these studies are to use non-invasive hair sampling techniques to snag
hair from animals, without ever seeing (unfortunately), touching,
or capturing the animal of interest. Once hair samples are collected, DNA
extracted from the hair follicle can then be analyzed in the laboratory for
species, sex, individual identification, genetic diversity, and even
parent-offspring relationships. This analysis will help us determine the
presence of grizzly bears, the sex ratio of animals sampled, and the minimum
numbers of bears present in our study area.
Field Work: We collected hair samples between
May and September. A hair-snag site is set up as a single strand of barbed-wire
around a clump of trees. The wire is positioned about knee height (approximately
50 cm) from the ground, so that small animals can easily walk under the wire,
and large animals can easily walk over the wire. A pungent, liquid attractant is
placed in the center of the perimeter fence, either on a downed log or on a
tree. In contrast to traditional baiting methods, our attractant provides no
reward that would habituate bears to a food source, to humans, or to the site
itself.
When curious bears approach the site, loose hairs are snagged
by the barbed wire. This technique was tested at Washington State University’s
Bear Research Facility and was found not to harm bears; in fact, barbs were
found to pull only 3 mm of hair from the animal without breaking the skin. We
collect hairs delicately with sterilized forceps, and the samples were placed in
envelopes to be dried and sent to the laboratory for genetic analysis. It is
important to revisit a site within 14 days after the initial setup, because
after this critical window of time, the DNA within a hair sample will begin to
degradade. Sites are left up for a total of 4 weeks, then dismantled and
removed.
Laboratory Work:To identify presence and minimum
numbers of grizzly bears in the North Cascades, hair samples are analyzed for
species identification. Once the DNA is removed from the hair follicle, it is
replicated using a process called Polymerase Chain Reaction (PCR), thus
exponentially increases the amount of DNA we have to work with. Brown bear
samples can then be separated from black bear samples using new genetic
technology called Applied Biosystem (ABI) fluorescent labeling systems (see
figure 1). To identify how many individuals we sampled, we use microsatellite
analysis, which identifies repeat sequences on the DNA (see figure 2). Think of
the microsatellite analysis as DNA fingerprinting; no two individuals are
exactly alike. DNA fingerprinting also allows us to measure how closely related
individuals are to one another (parent to offspring), and how their genes
compare to other brown bear populations in surrounding areas of the U.S. and in
Canada.
Protecting wilderness means protecting the species of both
plants and animals that inhabit the land. I feel it is important to realize that
since humans hunted many populations of wildlife nearly to extinction, it is our
responsibility to care for the land in a way that allows for the restoration of
wildlife populations and encourages them to thrive in their native habitat. To
ultimately help grizzly bear recovery efforts in the North Cascades, we first
need to know and understand the population that may still exist. This knowledge
will help us make practical decisions on how to manage modern human impacts,
from campsite and trail development to resource extraction, on wilderness and
public lands of Washington. I hope my study will enable us to answer the
question "where are the grizzlies", and help us gain a better
understanding of the North Cascade grizzly bear population and their recovery
needs. If you have any further questions or comments, please feel free to
contact me at Washington State University- Department of Natural Resource
Sciences.
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