Mark Naniot has seen it all too often. Loggers, unaware of black bear dens while cutting timber in Wisconsin's winter north woods, may get too close to a sow and her offspring.
The sow leaves the den and runs away. Sometimes, she may return after loggers leave. Other times, her cubs are left to die or become rescued by the loggers. Fortunately, the majority of loggers take abandoned cubs to rehabilitators such as Naniot, director of rehabilitation at Northwoods Wildlife Center, Inc. in Minocqua, Wis., for the past 13 years.
Naniot recalls what happened in mid-February.
"It happened during a logging operation in Langlade County near Antigo. The guys got too close to mom and she ran off and abandoned the two cubs," he said. "They went back to check the next day to see if the sow came back, but she didn't. One of the cubs froze to death. They brought the other one to us."
Bear cubs are typically born the second week of January. Naniot said this particular female cub was brought into Northwoods on Feb. 19, so he believes it was about 4 or 5 weeks old.
"She weighed about 3 pounds when we first got her and almost 6 pounds when we released her on March 3 near Cornell," he said.
The original plan was to place the cub in a den with a sow and her offspring near Cornell. However, when researchers tranquilized the sow and pulled her from the den, they discovered she already had four cubs about the same size of the orphan cub.
"Occasionally, a sow can take five cubs, but it's pretty hard," he said. "It's very rare that a sow will have five of her own. That's a lot for mom to handle. Typically, they can't produce enough milk for that many."
Fortunately, another "denned up" sow that was radio-collared the previous year was located within a few miles. Naniot and Mike Gappa, former Wisconsin Department of Natural Resources West-Central Region wildlife manager, placed the orphan with that sow.
The tactic worked to perfection as Naniot was able to place the orphan cub in with her new mom with no problems.
"There was a hole on the back side of the den. I sneaked around. Mom was back there and I dropped the little one on top of her," said Naniot, adding that the big sow's three cubs were by her side.
"She didn't bat an eye," he said. "She can't count for one thing. A sow is very dedicated and will take care of the cubs whether they are her own or not."
At last report, the sow, her three cubs and her orphan daughter were doing well.
Naniot said sows begin to wean cubs in mid-May, although it depends how much food is available.
"Bears coming out of their dens are weather dependent. A sow will stay in as long as she can so the little ones are agile enough to climb trees and escape predators," he said. "This sow and her cubs probably came out in late March. Usually, they come out a week or two into April, but this year it was probably two to three weeks earlier because of the warm weather."
That may not be good news for the sow's three cubs and her orphan. Cubs are more at risk because they may not be strong enough to climb trees and follow mom as they should, Naniot said. If the little ones are unable to climb trees, they may become separated from mom and fall prey to predators, including wolves, or black bear boars, which prey on them.
Boars will eat the cubs, simply because they are good, available prey, Naniot said.
He said the rehabilitation center accepts orphan cubs as young as 2 weeks old. Naniot also takes cubs until the first part of July. After that, he said they usually weigh 30-35 pounds and are able to take care of themselves.
"We usually average about four to five orphan cubs a winter, but it's been increasing," he said during an interview in late March. "We had 17 in 2009 and 25 in 2008, but that was for the whole year. So far this year, it's been three."
Cubs taken to the rehabilitation center in late spring or summer are carefully cared for, monitored, and then released in the fall.
Naniot said cubs brought to the center will eventually weigh between 80-120 pounds by next fall rather than 50-70 pounds if in the wild with their mothers.
"But you have to understand, our cubs get more nutritious food," said Naniot, adding that he and his staff are very careful around orphan cubs.
Bears, like most animals, will easily imprint on humans. That's why Naniot begins feeding the cubs by bottle, then food from a dish and eventually from a two-sided cage where they are unable to see humans providing their food.
"We try to let them know that humans are a bad experience," he said. "We'll bang on pots and pans around their cages if they see us."
Naniot said Northwoods Wildlife Center releases orphan cubs in several areas of the state, refusing to name specific locations. However, he emphasized that release sites are far away from humans.
Orphan cubs received in May, June or July also are released late in fall, a week or two before they go into a winter den.
"They'll just go hibernate and sleep it off. By next spring, they will be more wild when they wake up," Naniot said with a smile.