Humans struggling to cope with the worst drought in Maine’s history might take a lesson on adaptability from the state’s wildlife.

Scientists are surprised to report that Maine’s black bears seem to be weathering food shortages with no ill effect and have produced a healthy crop of cubs.

“The word adaptable with a capital A is what a bear is,” Craig McLaughlin, a wildlife biologist with the Department of Inland Fisheries and Wildlife, said Friday. “They continually amaze me.”

McLaughlin has studied Maine’s black bears for two decades and fully expected that last summer’s drought would harm the health of the state’s 23,000 bears. But a recently completed annual survey of bear dens indicated that the black bears are generally healthy, and are reproducing at or above normal rates.

State biologists visited 43 dens through January, February and March and found 20 dens with adult female bears. Seven had litters of newborn cubs – double what biologists had anticipated.

“We expected lighter-weight bears, and few or none in terms of cubs produced,” McLaughlin said.

Black bears feed on berries and other wild vegetation through the summer months, but when they begin fattening up for hibernation in the fall, bears’ favorite forage is beechnuts.

Through years of study, biologists have observed that beechnut populations tend to be cyclical, with a prolific beechnut year followed by one in which the nuts are scarce.

“In years when there are a lot of beechnuts, they put on a lot of fat in the fall, go into the dens and produce a lot of cubs,” he said. “The question in my mind is, ‘Why are they producing cubs [this spring]?'”

Last year, a bad beechnut season on top of the continuing drought caused bears to lose summer berries as well as their fall staple food.

“Bears are vegetarians, to a large extent,” he said. “A lot of the crops that they feed on are really affected by drought.”

Biologists feared that bears might not have put on sufficient weight to sustain them through the winter. But bears survived the winter and weighed more than biologists had expected after the winter’s hibernation, probably because they turned to less-preferred but high-energy food choices, such as mountain ash berries or hazelnuts, said McLaughlin.

“They got enough food somewhere to get over the threshold,” he said.

Bears also typically go into their dens as much as a month earlier in a year when beechnuts are scarce, thus conserving their energy. While bears normally are active until November or December, most of them had settled in to hibernate by October last year.

“They’re only going to stay out as long as they can forage,” he said.

Although they aren’t always seen, black bears live in all parts of Maine except the heavily developed southern coast.

Litters of between two and four cubs are born in January or February, nearly hairless and weighing only about 12 ounces. By the time biologists visit the dens in March, healthy cubs have tripled or quadrupled their weight.

Female black bears give birth only once every two years and spend more than a year mothering their cubs. They reach sexual maturity at about 4 years of age, but many a new mother bear loses her first litter of cubs because she hasn’t yet learned to care for her young.

Five of the seven bears who gave birth this winter were only 5 years old, so although the crop of cubs was larger this spring, mortality rates could be unusually high.

McLaughlin feared that last spring’s cubs, which spent their first winter hibernating with their mothers, might have suffered high mortality last summer, but the den survey turned up a large population of healthy yearlings.

Of 38 cubs known to have been born last year, 27 were located in this winter’s survey – a survival rate of just over 70 percent. In past years, yearling survival has dipped as low as 50 percent and climbed as high as 75 percent.

McLaughlin carefully watches how bears of all ages respond in a year when traditional food sources are limited, to learn whether the availability of beechnuts limits Maine’s black bear population. Beech trees have little commercial value, and in many areas that are being harvested by foresters or developers, they are not among the trees included in reforesting efforts.

Additionally, a fungus known as beech bark disease has been sweeping through New England and Atlantic Canada, killing many of the beeches. Scientists are working with foresters to create new practices to protect the remaining wild beeches, but this year’s data suggest that Maine’s bears are adapting to different food sources when beech aren’t plentiful.

“We have no shortage of bears in the state of Maine; they’re a very abundant species,” McLaughlin said. “I don’t see any crisis in the bear population in the near future.”

Maine’s bear population had dropped to 18,000 during the late 1980s, but a shift in hunting regulations sparked a recovery, and biologists are now managing the population to maintain 23,000 bears.

That number was set by DIF&W in an attempt to balance the needs of the bears with the needs of Maine’s human population, and to reduce conflicts between the two.

“Anywhere you have bears and people sharing the landscape, you’re going to have some level of conflict,” McLaughlin said. “And the public can expect, if we have a continued drought, a higher-than-average number of bear conflicts this summer.”

Last summer, state biologists had dozens of calls from homeowners complaining of bears in suburban back yards. The animals ventured into neighborhoods drawn by food sources such as garbage cans, compost piles, bird feeders, dirty cooking grills and bowls of pet food.

McLaughlin discouraged homeowners from feeding the hungry bears – even accidentally – as they can quickly develop a habit of reliance on humans for easy meals. People should refrain from placing any strong-smelling food items outside, particularly at night.

Black bears are nearly vegetarians, and don’t typically attack pets or people.

“They’re not predators of children,” McLaughlin said. “But people see a big animal in their back yard, and they’re concerned.”

If faced with a black bear, the biologist recommends, people should make loud noises to frighten it off, and back away very slowly. The best defense, however, is not to attract bears to a residential area in the first place.

“We’d like to keep our wild things wild,” McLaughlin said.