For more than 33 years, Randy Cross has studied Maine’s black bears, accumulating data that helps the state formulate its management plan for the iconic animals.
And the bears never cease to amaze the wildlife biologist for the Maine Department of Inland Fisheries and Wildlife.
Walk into his appropriately dark, basement level office — picture a bear’s den with computers and chairs — and Cross is happy to explore the mysteries of the bear world, one case at a time.
On Wednesday, during an hour-long conversation, Cross addressed three different cases that are equally intriguing. Among the topics covered: The recently solved mystery of a long-lost research bear, a six-cub litter in Aroostook County and the extreme weight loss that male bears can experience during mating season.
What happened to Karen?
Back in 2002, the DIF&W bear crew received some bad news: Some of their bears were missing.
In truth, the bears hadn’t gone anywhere, Cross said. They were still in the woods, doing what bears do. But at least seven of the female bears that researchers were tracking had become virtually invisible to them after a technological mishap.
“We lost them all at once,” Cross said, explaining that the radio collars on those bears all stopped working at the same time, three years into what biologists thought would be a four-year lifespan of the equipment. “We found out in April that there was something going on — the pilots couldn’t find the [signals from the] bears. We’d just been in there [to the dens] a month before, and everything was working fine.”
Among those lost was “Karen,” a daughter of “Sara,” the bear who has produced more than 100 descendants in the study.
At the time, Karen was 19 years old. And biologists never saw her again.
This week, Cross received an email from a game warden in Aroostook County who passed along some news that would seem surprising to some … but not to Cross.
Karen had been shot by a hunter, and her 16-year-old radio collar was still around her neck. Karen was 32½ years old — ancient for a black bear — and Cross said the news confirmed what he’d always expected: Karen was still out there, somewhere.
Cross said he reached out to two biologists who had also dealt with the bear, passing along the news. And despite the bear’s demise, Cross was happy that he finally had closure.
“It’s one of those things where people say, ‘How can you be happy to hear that a bear’s dead?’” Cross said. “I’m happy to hear that the bear was doing well for 13 years [since we lost track of her].”
Cross also said that an elderly bear’s life isn’t an easy one.
“I’d almost guarantee you that she was almost totally blind,” Cross said. “A 30-year-old has really cloudy eyes. And they’re not doing well [physically] by the time they get into their 30s.”
Bear weight-loss program
Want to lose weight like a bear? Well, there are at least two ways to do that. First, you can go to bed for six months and refuse to eat. That’ll probably work.
Or, you can do what “Dozer” the bear — and other males — do: Focus your life on mating.
Last week Cross passed along data on Dozer, a bear that he and the crew caught twice during the spring capture season, as they were trying to live-trap females to add to the study group.
Over that 12-day span between captures, the 20-year-old bruiser lost 34 pounds, dropping from 442 pounds to 408.
During that breeding period, which starts in late May, peaks in mid June, and can last until August, the bears eat sparingly while on the run, and spend much of their time pursuing females and fighting for the opportunity to breed with them, he said.
And younger bears lose weight even more rapidly, Cross said.
“The ones that will lose the most weight are the ones that are just getting big enough to really try hard [to find a mate],” Cross said. “When they’re 5 or 6 they’re getting to the size to the point where they feel like they have a reasonable chance of success.”
In order to have that “success,” Cross said they’ll likely have to fight off bigger bears in order to mate with the female. The smaller the bear, the more fighting he’ll have to do.
And the fights are frequent.
“They’re going to fight a lot more than a big guy like Dozer, who’s going to walk in with not many marks on him,” Cross said.
“Those ones that are just getting into it, they’re fighting like crazy,” he said. “They’re fighting everyone.”
And they’re losing weight in the process.
Six cubs in a litter?
Finally, Cross said there’s a bear-related mystery in Aroostook National Wildlife Refuge in Caswell that biologists will likely never solve: Several people have seen a six-cub litter running around.
Cross said he has seen an occasional four-cub litter, but never a five-cub group from the same mother. Six? While possible, he’s got questions.
“You don’t know if they’re natural-born,” Cross said, explaining that in some cases, bear cubs are “adopted” or misplaced, and end up growing up with another mother’s cubs.
“One [of our study bears] started with three female cubs [when we visited the den] and ended up with one of her own female cubs, and two females and a male cub from some other bear [when we visited a year later],” Cross said. “I think it was a cub swap, and probably with [the litter of] her granddaughter or daughter.”
There is a way to find out if the six cubs are siblings, but Cross said the DIF&W isn’t apt to do so.
“Of course, the first thing you think of is to get a warden with a culvert trap, get out there, catch ‘em all, and take genetic samples to make sure they’re all hers and not adopted,” Cross said. “But there’s not a reason to really do that except ‘It would be cool to know.’ It’s not going to change our management because of one freak occurrence, because it really would be a freak occurrence [for a single bear to raise six cubs].”
Cross said that even in litters of four cubs, the survival of all four isn’t guaranteed, and he thinks it’s fairly likely that these six cubs are not from the same litter.
When six cubs are vying for nutrition and the mother bear is trying to keep them safe at the same time, the odds are against the survival of all of the bears.
“I would expect most six-cub litters to only be [reduced to] three or four at this time [of year] because of the trouble trying to produce enough milk for that many and to keep track of them and keep any of them from being predated or just lost or separated or something,” Cross said.