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This photo shows a glacier bear walking along rocky terrain. There are four known populations of black
bears in Southeast Alaska that include the lighter-colored bears, said Tania Lewis, a wildlife biologist for
the National Park Service at Glacier Bay National Park and Preserve. (Courtesy Photo / Tom Hausler)
Recessive genes and
receding glaciers:
Lecture focuses on
Southeast’s blue bears
Biologist shares insights about glacier bears.
By Ben Hohenstatt
Saturday, January 15, 2022 6:43pm ❙
ALASKA OUTDOORS
SCIENCE
NEWS
WILDLIFE
Until recently, not much was known about the
grayish bears sometimes spotted in Southeast
Alaska, said Tania Lewis, a wildlife biologist for
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the National Park Service at Glacier Bay National
Park and Preserve.
The bears — known as “glacier bears” in
English and sik noon ”bear that disappears” in
Lingít — are unique to Southeast Alaska with a
genetic history influenced by the region’s
glaciation, according to Lewis.
A better understanding of the bears has emerged
thanks to research spanning over a decade and
including samples from hundreds of bears.
During a virtual installation in the U.S. Forest
Service’s popular Fireside Lecture series, Lewis
shared insights researchers gleaned, theories
about why the bears have their captivating
coloration and how a better understanding of
the rare bears started with nuisance animals in
Juneau.
Tania Lewis, a wildlife biologist for the National Park Service at Glacier Bay National Park and Preserve,
spoke about glacier bears during a virtual Fireside Lecture on Friday. The lectures, a popular series held by
the U.S. Forest Service, are free and scheduled for Friday evenings through March. (Courtesy Photo / Tania
Lewis)
A bear of a different color
Despite their name, black bears aren’t always black, Lewis said, although
that is the most common color.
Glacier bears are one color variation. Others include the relatively common
cinnamon-colored black bears and the white kermode bears, also known as
“spirit bears,” found on the coast of British Columbia.
Even within glacier bears, there are color variations, Lewis said.
“They’re mostly gray, but they can be almost white or even black with just
white tips,” Lewis said.
Colorful theories
There are multiple theories about why the bears have their unusual color.
Since the known population of bears are near ice fields, Lewis said it is
thought the color may offer a camouflage advantage.
“Maybe there’s an association or potentially a selective advantage between
coloration and ice-covered areas,” Lewis said.
Additionally, Lewis said studies done on similarly colored kermode bears,
found the lighter color is advantageous when catching salmon as it allows
the bears to better blend in with the sky.
Lewis said as is the case with spirit bears, the coat color seems to come from
a recessive gene that came about during isolation during an ice age.
Since the gene is recessive, it must be present in both parents for offspring
to present it, and a bear can carry the gene while looking like an otherwise
typical black bear.
That means a normal-colored bear can potentially have glacier bear cubs.
Black bears with more typical coloration can produce offspring with grayish coats. Bears with with the
coloring are known as glacier bears. There are multiple theories for why the bears have their unusual
coloration. They include a potential camouflage advantage in icy terrain and possibly an advantage when
catching salmon. (Courtesy Photo / Cody Edwards)
Same size as other black bears
It was long thought that glacier bears are typically smaller than black bears.
However, harvest records show no size difference between glacier bears,
cinnamon-colored black bears and black-colored black bears.
“There’s probably no difference from any other black bear other than their
coat color,” Lewis said.
Why did the size discrepancy rumor persist?
Lewis said she has no hard evidence, but she thinks it may stem from trophy
hunting.
Typically, she said, trophy hunters would want to take an especially large
bear. However, glacier bears may have been sought regardless of their size
because of their atypical color.
That could have created a false impression that glacier bears were smaller
than black- or cinnamon-colored bears.
Rare bears
While Lewis said it was difficult to get a hard count on the number of glacier
bears in the area, she said for many seeing one would be a once-in-alifetime event.
About one glacier bear is harvested every year in the portion of Southeast
Alaska from Juneau to Haines, Lewis said, and about 1-4 are harvested every
year near Yakutat.
That accounts for .4% of black bears harvested in Southeast Alaska, Lewis
said.
Lewis said sightings and harvests have stayed relatively steady over the
years, and the numbers are too small to allow for an estimate of how many
glacier bears reside in Southeast Alaska.
With an apparent link between the bears and ice fields, Lewis said how
climate change will affect glacier bears is an open question.
“Deglaciation of this region started a long time ago, but it is being greatly
accelerated by human activity,” Lewis said.
She said that includes some positives, such as potential range expansion
fueled by an increase in habitat and an increase in berries and flowers in
warmer weather.
“But there are some bad sides, too,” Lewis said.
These include the loss of alpine habitat, weather inhospitable to salmon and
ocean acidification. Additionally, populations kept separate by melting
glaciers could come into contact, and glacier bear genetics could be diluted.
“There is some potential threats from climate change, specifically for
glacier bears,” Lewis said.
She said bear conservation, including not allowing bears access to human
food, and fighting climate change are good for both glacier bears and their
more typically colored counterparts.
Capital city connection
A research project that included tissue and hair samples from hundreds of
black bears was jump-started by a glacier bear in Juneau.
In the early ’00s, multiple nuisance glacier bears in Juneau were relocated
out of town and a few died after being struck by vehicles on Egan Drive,
Lewis said.
She said it’s likely the bears were related to each other.
While Lewis said people at the time seemed unaware of the rarity of the
bears, Alaska Department of Fish and Game Biologist Neil Barten recognized
the unlikely opportunity. Barten took samples from the dead bears.
“Those were the first samples that we got,” Lewis said.
Over a decade and hundreds of hair and tissue samples later, research
revealed 10 distinct populations of black bears around Southeast Alaska —
generally separated by fjords and ice.
Of those populations, four were found to have glacier bears, including
populations located near Yakutat, the western area of Glacier Bay, Haines
and Skagway and Juneau.
It notably did not include a population of bears located on the Chilkat
Peninsula that reside in between two populations known to include glacier
bears, Lewis said.
“The Chilkat, while it does have some glaciers high in the mountains, it’s
not a big ice area, it’s more just snow-covered mountains, so that suggests
there’s either an unsampled population of black bears with glacier bears
connected these, ” Lewis said, adding a northern corridor could be a
possible location. “Or maybe there’s an association or possibly selective
advantage for glacier bears with large ice fields.”
Watch the full Fireside Lecture below
What is a glacier bear and where can I get one?
U.S. Forest Service - Mendenhall Glacier Visitor Center was live
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• Contact Ben Hohenstatt at (907)308-4895 or bhohenstatt@juneauempire.com.
Follow him on Twitter at @BenHohenstatt.
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