Bear study links surrogate sows with orphaned cubs

By Bill
Parker
Editor

Cheboygan County, Mich. — Ron Girard decided to take a walk on
the third day of the 2004 firearms deer season. He never guessed
he’d stumble into the middle of a program that aids black bears in
northern Lower Michigan.

Girard walked into an area and found a hole in the side of a
bank and some dirt that had recently been kicked up. Curious, he
moved in for a closer look.

“I peaked into the hole and saw a lot of black fur,” the
Cheboygan County resident said, excitement still hovering in his
voice a year after the find. “I stopped by the DNR station in
Gaylord and told them. A couple days later, I got a call from Mark
Boersen.”

Girard was just the guy Boersen was looking for.

Boersen is a wildlife biologist with the DNR working out of the
Roscommon Operations Service Center. He’s running a program in the
northern Lower Peninsula intended to introduce orphaned black bear
cubs to surrogate sows.

DNR biologists in the northern Lower end up with orphaned cubs
about once every year or so, according to Boersen.

“For whatever reason, we end up with anywhere from one to four
orphaned cubs,” he said. “The problem is, what to do with those
little cubs. Do we give them to a zoo, give them to a rehabilitator
and hope they can be reintroduced into to the wild later, or give
them to a surrogate sow that already has cubs of her own?

“Research has shown – and we’ve done it in the Upper Peninsula –
that you can introduce orphaned cubs to a mother with cubs and
she’ll accept them as her own,” Boersen said.

Doug Wagner, a DNR wildlife biologist at Crystal Falls in the
western U.P., said he and his crew have placed several cubs with
surrogate sows during the past few years.

“Actually, we’ve fostered in eight or nine cubs into dens,”
Wagner said. “It’s a relatively easy process. They (sows) don’t
seem to recognize cubs by smell while they’re still in the den, so
if you find a sow that’s capable and drop in a cub, she’ll usually
accept it as her own. Once they leave the den, it’s tougher.”

The key to successful introduction of a cub is finding a sow
that’s capable of being a surrogate. That task is what took Girard,
Boersen, and several other biologists and researchers deep into the
Mackinaw State Forest on a recent sunny morning. Their mission was
to check up on the sow Girard found in the fall of 2004. Boersen
and his crew put a tracking collar on that sow last January so they
could track her movement and use her as a possible surrogate in the
future. At that time, she had three cubs with her – two males and a
female.

This year’s check revealed the sow had moved to a new den,
approximately three miles from where she denned last year. The sow
is healthy and in good physical condition and at least two of the
cubs survived the year and were denning with the sow. “There could
have been a third cub in there,” Boersen said. “The den is huge,
and sometimes you don’t always see them all.”

The cubs, which are technically yearlings now, will stay with
the sow into June or July of this year. At that time, the sow will
come into heat and will chase away her cubs so there won’t be any
conflicts with an aggressive male that may show up to mate. By next
January, she should have a new litter of cubs – and be a potential
candidate as a surrogate.

Boersen collared another sow in Arenac County. He hopes to
collar between six and 10 for the program.

A sow will reproduce every other year and will only be a
candidate for a surrogate during the years it has a litter of cubs
– usually between two and four per litter here in Michigan.
Collaring 10 sows will give biologists several options.

“Sometimes we can’t get to a den, or if a sow already has three
or four cubs we don’t want to give her another one and give her the
added stress,” Boersen said. “That’s why we need several options.
So far we have two sows collared, but we’re still in the early
stages of the project.”

He also faces a bit of a dilemma in dealing with bears in the TB
Zone in the northeastern Lower, which is another reason for wanting
to collar 10 sows.

“We don’t want to take cubs out of the TB Zone,” Boersen said.
“The risk (of spreading TB) is very, very small, but we just don’t
want to do it. We can bring orphans into the area, but not out of
the area.”

Wagner said there are five sows collared in the U.P. and that he
hopes to have six collared by the end of denning season, which can
run into April in some parts of the U.P.

“The public has made it clear they do not want us to euthanize
cubs, and they prefer that we don’t give them to a zoo; plus, most
zoos already have all the bears they want. The surrogate mother
option seemed like the best idea,” Boersen said.

The DNR has asked for public assistance in locating bear dens.
(Note: It is illegal to disturb a bear den or disturb, harm or
molest a bear in its den.) Biologists ask that persons who find a
den note the location on a GPS and call Boersen at (989)
275-5167.

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