Hi, my name's Nate Bowersock. I'm a graduate student in the Department
of Ecology at Montana State University. As you might be able to guess, I've always
been quite fascinated with wildlife in the outdoors. Early in my undergrad
career, I got the amazing opportunity to assist with research on the wolves and
moose of Isle Royale in Michigan. From this experience, led to me migrating west to
the Greater Yellowstone Ecosystem nearly ten years ago now to study the wolves of
Yellowstone. From my time studying wolves, I learned that wolves play an important
role in helping keep balance between ungulates and local plant communities.
However, I soon found out that wolves are not the only predator to help keep
balance in an ecosystem. Bears, both black and grizzly, also helped keep balance in
ecosystem. And in a study in the early 2000s in Yellowstone found that bears
accounted for 69% of all predator-related mortality of neonate elk calves
or newborn elk calves. Compared to wolves only accounted for 12%. Now I became
quite fascinated with bears and especially their ability to be able to
switch their diets according to the availability of resources on the landscape.
And this is one of many reasons why I switched gears and started studying
bears. The black bears are the most well-distributed bear species in North
America, and had been well established in the GYE
for hundreds of years. The GYE is one of the few places in the lower 48 where
both black bears and grizzly bears coexist with one another. We know a lot
about grizzly bears in this area due to their threatened status. However, we don't
know nearly as much about black bears. What we do know about black bears,
is they are omnivores, and most people associate them with consuming diets
mainly of vegetation and insects. However, most people don't realize that black
bears are predators. That's right, folks, black bears are predators and they do
hunt and kill prey. In ecosystems where multiple predators are present, black
bears are usually the most efficient predator to consume neonate ungulates on
the landscape, unless grizzly bears are present.
Now in 2014, I got the opportunity to lead a pilot study using GPS camera
collars to document the daily behaviors and food selection of bears in Yellowstone.
[Sounds of bear foraging and eating]
From our study, we were able to show that black bears are more day-active than
grizzly bears, but that both species ate quite a bit of vegetation. The biggest
difference we saw between these two species was that black bears ate more
insects, while grizzly bears eight more vertebrates. Now, these results are pretty
consistent with other studies in the region and show that grizzly bears eat
more energy-rich resources, which allow them to grow bigger and out-compete
black bears. And this was intriguing to me, because black bears are observed more
often than grizzly bears on the Northern Range of Yellowstone. And, this was
interesting to me because if grizzly bears are able to eat more energy-rich
resources, then how are there more black bears on on the landscape? One hypothesis
that came to mind is that maybe black bears are following resource waves.
Resource waves are naturally occurring events when energy-rich resources become
temporarily available on the landscape. For example, in Alaska, bears have been
documented to follow the red wave, which is when the annual salmon spawning run
is occurring. The bears congregate around streams to consume an energy-rich
resource that allows them to prepare for hibernation. Now, closer to the home in
the GYE, ungulates such as elk have been documented to follow the Green Wave,
which is when green vegetation is at its peak foraging quality, but at low
abundance on the landscape. By following resource waves, animals are able to
better utilize the resources around them, which could allow them to survive longer
on the landscape. Now, in 2016, I started my graduate study to look into
ecological questions related to black bears on the Northern Range. My project
has three main objectives: 1) just to determine if black bears are following
the Green Wave, 2) to better understand the predatory behaviors of black bears
towards neonate elk calves, and 3) to document how many black bears and
grizzly bears there are on the landscape. To conduct this study, we collared
eight black bears between 2017 and 2018 with standard GPS collars that took hourly
locations of where the bears were going.
By taking such fine-scale locational information, we can not only look at what
the quality of resources that bears are consuming, but also what other resources
they might be selecting for, such as are they selecting areas where elk are
having their calves. And finally, my crew and I hiked across our study area to
look for rub trees which are naturally occurring trees that bears rub on a
regular basis to potentially communicate with one another, but also is
a great source of hair. So, along with the barbed wire hair snares we set up on the
landscape, allowed us to collect hair on a regular basis so we can
conduct non-invasive DNA population analysis. From our study, we're hoping to
document whether black bears are following the Green Wave. If we are able
to determine if black bears are following the Green Wave, then this may be
a way that we're showing black bears are able to utilize the resources around
them more efficiently, which could give them a competitive edge to still compete
with grizzly bears. We also want to determine whether black bears are
opportunistically or actively seeking out elk calves, which will provide new
information on the roles black bears play in the predation of elk calves.
And finally, we hope to determine how many black bears and grizzly bears there
really are on the Northern Range, but also how well they're distributed across
this landscape so we can better understand how these two species coexist
with one another. This study will hopefully answer questions that
previously were unknown about black bears, and we hope to generate new
questions to help us better understand this iconic species in Yellowstone.
Thank you!