Lake Clark National Park is bear country.
Inland brown bears are found throughout most of the park's
four million acres. The park's inland brown bear habitat is divided into two parts by the
Chigmit Mountains, part of the Aleutian Range. East of the mountains, along the Cook
Inlet Coast, are resource rich coastal habitats where coastal brown bears
forage in salt marshes, dig razor clams along the shore and fish for salmon.
These rich habitats support large numbers of bears living close together. Some of
the highest bear densities in Alaska have been recorded along the coastline
of Lake Clark National Park. West of the Chigmit Mountains is an inland habitat
that is very different. Food resources are widely distributed across the
landscape. We know little about how brown bears use these inland habitats.
LINDSEY STUTZMAN: Brown bears are both a culturally and economically important species in the
state of Alaska. And bear viewing generates substantial revenue for local
economies. And brown bears are also a keystone species, so they're really
important for judging the overall health of an ecosystem. Despite all of this
importance, very little is actually known about the brown bears in Lake Clark.
We know on the coast that there's probably about a hundred and fifty brown bears
per thousand square kilometers and then we also have a basic estimate of
densities in the interior, which is about 39 brown bears per thousand
kilometers squared. But other than a basic density we don't really know very
much about them. We don't know about the resources that they're selecting for. We
don't know where they den. Basically we are lacking a lot of basic information on the
ecology of the bears in the interior.
NARRATOR: In an effort to better understand the lives
of inland brown bears, scientist from the National Park Service, United States
Geological Survey, University of Alaska Anchorage and Mississippi State
University are undertaking a four-year study to examine how brown bears are utilizing
the inland habitat in the park. And how that use changes over the course of the year.
Using GPS radio collars, researchers are trying to answer three key questions
about Lake Clark's inland brown bears.
LINDSEYSTUTZMAN: We're really interested in looking at
specific home ranges of different sex and age classes of bears. Specifically
looking at how male bears will use the landscape differently than female bears.
And within females, are they using it differently when they have cubs of the
year versus yearlings? And basically how they're using that in relation to other
bears. We're also really interested in looking at what areas the bears are
using specifically and what resources might potentially be in these areas to
determine what is driving the movements of the bears. For example are they
moving long distances to get salmon? Are they staying in specific areas where
they know there's a lot of good vegetation to eat? So it's gonna be really
interesting to see how they're using the landscape and what they're home ranges are like.
BUCK MANGIPANE: So far what we've found is all the mountainous habitat in
inland Lake Clark provides denning habitat for bears. We've had them
widespread throughout the southern portion of the interior. What's been more
interesting is after they emerged from the dens, in terms of the home range use
for bears. We've had some bears that have moved over a hundred miles and had
large home ranges, maybe up to 2,000 square miles. Whereas we have other bears
that have never moved greater than 10 miles from their den sites. So they have really
small ranges, about 40 square miles. So they seem to be choosing and using
resources differently and that's reflected in kind of their home range size.
LINDSEY STUTZMAN: Another component of that is we're really interested in looking at the behavioral
aspect of denning. So if male bears and female bears are denning in
different areas and what's driving that. Specifically, are females with cubs denning in
harder to get to areas, that are high elevation steep slopes in order to
avoid predation on their cubs? Or are they denning in areas where they might
have easier access to high-quality food resources when they emerged in the spring?
So it'll be really interesting to look at these components and see what
specifically is driving where they den and why, as well as the timing of denning.
BUCK MANGIPANE: So far one of the
really interesting facets, I think, that we've found truly noteworthy is, if you look
look at the range of Gates of the Arctic, Lake Clark and Kodiak ,we go from the extreme
north of Alaska to some of the harshest habitat that bears exists in, all the way
to Kodiak Island which is some of the luscious most productive bear habitat in
the world. Within those bears are obviously making a living. What we
found with Lake Clark bears is some of the bears are showing signs that their diet
composition is very similar to what a bear that lives on the North Slope would
have. So primarily terrestrial prey and not necessarily that rich in salmon resources.
Having actually no, to limited access to salmon. Whereas other
bears are showing that they're using salmon as extensively as bears on Kodiak
Island. So what it shows us, is that in the interior of Lake Clark we have a broad
spectrum of habitat that has various levels of quality. And bears are choosing to
use those differently. And what also is interesting is with location data we've
collected since den emergence this year, we've seen that all the bears have salmon
nearby. So the fact that some are choosing not to use salmon as a resource seems
really interesting and kind of surprising.
Lindsey Stutzman: So it's been really interesting seeing some of the movements of these bears. Specifically the bears that have moved west.
We've had numerous bears move really far distances and two speciically have moved
over a hundred miles from where we originally captured them. It's been really
interesting seeing them make these big moves and how they've done them so
quickly and these areas are full of a lot of salmon streams. So it's really
interesting seeing the bears moved to the areas that might receive salmon sooner
than the interior parts of the park.
BUCK MANGIPANE: On the other hand we've had several bears
that have never gone more than nine or ten miles from their den site, so very
small-scale movements and living in small areas. So very isolated movements
that they're making and they're obviously meeting all their resource needs there.
So very wide-ranging variability in movement patterns.
NARRATOR: These preliminary results are not only giving us the first glimpses into Lake Clark's
inland brown bear population, but they're beginning to point to the
diversity of strategies that individual bears use to survive in the park's more
resource constrained inland habitats. Answering these three basic questions
will create a baseline for long-term monitoring of the inland brown bear
population, helping ensure that we understand and effectively protect these
magnificent and powerful creatures.