Counting Bears

Cubs stay with their mothers for 16 months. Photo by Chris Crowley.

Biologists monitor the vitality of the “living symbol of the Maine woods.”

The past two days have been disappointing for state bear biologists, and today is shaping up no differently. Fifty leg snares at 37 sites have turned up exactly zero bears.

“Four days ago, we had four,” says Randy Cross, bear biologist for the Maine Department of Inland Fisheries and Wildlife. Since they started this year’s bear study in May, they’ve averaged one and a half bears a day.

One team member, Eric Rudolph, has yet to return to the rendezvous point, so Cross and his team still hold out hope for something. “We’re due,” Cross says, puffing on a pipe to keep the cloud of blackflies at bay. “Three days without anything would be really unusual.”

Cross’s team has monitored black bear activity in Washington County, the state’s easternmost county, for six years. The biologists catch the bears with leghold snares, tranquilize them, gather data, and tag them before releasing them unharmed. The Studmill Road, which cuts through the Beddington study area, serves as the main artery from which Cross and his team delve into the forest on their rounds. Other study areas have focused on Stacyville, Bradford, and Spectacle Pond, which is west of Ashland.

The study is part of a project that dates back to 1975, the year state bear biologists began a systematic, scientific attempt to track Maine’s black bear population.

“We’ve learned a lot about bears through this study over the years,” Cross says. “It’s invaluable, really. It’s helped us meet the needs of many, many different groups of people and, of course, it’s helped us take care of an iconic living symbol of the Maine woods.”

Black bears have the widest range of North America’s three bear species. They inhabit forested areas from Mexico to Canada and Alaska. They’re the only bear species that lives in the eastern U.S., and because they’re so adaptable, they can live in close proximity to humans. Biologists estimate that Maine has a population of around 27,000 black bears, although Cross admits that number may be a little conservative.

As omnivores, bears are highly opportunistic feeders. They’ll eat nearly anything, and their diet shifts over the course of a year depending on the seasonal availability of food sources – raspberries in midsummer, for instance, and black cherries, beech nuts, and acorns in fall. Depending on the time of year and the quality of their food sources, their weight can vary widely. Adult males range anywhere from 250 to 600 pounds; adult females typically weigh between 100 and 400 pounds.

“Our goal is to maintain a stable population,” explains Cross, who has been working with the state’s bears for 27 years. The trick he says, it to balance the ecological carrying capacity of the land with what he calls the “social carrying capacity” – what society will tolerate.

“The land could sustain more bears, but the problem is that more bears would mean a higher incidence of nuisance calls,” he says. “We’re at a tolerable level right now; the public might not like having so many nuisance bears, but they’ll tolerate this level. Any more, and you’d probably see public opinion turn negative.”

So each year, Cross and his team venture into the woods to monitor the black bear population. The program gets three quarters of its funding through federal taxes on firearms and ammunition, while the other quarter comes primarily from state hunting license fees.

Much of their time is spent tracking female bears with radio collars. “That lets us find them during the winter while they’re hibernating,” Cross says. “We can go into the dens and see how many cubs are born.” Cubs also get tagged for future tracking purposes.

Because cubs stay with their mothers for 16 months, biologists can find out how many cubs survive to be at least a year old. Cross says cub survival is highly variable and difficult to predict, ranging anywhere from 10 to 60 percent. “That’s why it’s so important to keep tabs on this,” he says. The leading causes of infant death are starvation and predation by adult males.

By the time cubs reach two years, though, their survival rate hits about 90 percent. After that, most bear deaths are the result of hunting and other human-related causes.

“So keeping track of births isn’t enough,” says Cross. “We need to determine survival rates. If we get a sense of how many cubs are surviving, then we know how many bears are entering the population.”

That, says Cross, helps the Department of Inland Fisheries and Wildlife better regulate the fall bear harvest. “We can make sure the number of animals being taken from the population corresponds with the number of animals growing up to enter the population,” he says. The result is a stable population that balances the needs of sportsmen and residents while ensuring adequate space for the bears themselves.

“Being in the field lets us make better management decisions based on real data,” Cross says. “This isn’t armchair management.”

Counting Bears Image

Photo courtesy of the Maine Dept. of Inland Fisheries & Wildlife Collections.

Bear vs. Deer

One of the big recent management challenges for state biologists relates to the impact of bears on the state’s deer population. The state’s deer herd has dropped to historically low levels, with some areas in northern and eastern Maine supporting only a single deer per square mile. As a result, the state’s $200-milliona-year deer-hunting industry faces a crisis.

“Half of the state has seen its economic base dry up because the deer are gone,” says former state deer biologist Gerry Lavigne. The hunters who sought those deer pumped millions into lodging, restaurants, guide services, and other hunting related business – most of it in economically depressed parts of the state. “That industry primarily helped rural communities, and a lot of that is gone now.”

While coyotes are often blamed for the whitetail’s decline, bears also prey on young deer in the spring, before the fawns are old enough to outrun predators.

Cross points to “a very well-done fawn predation study in Pennsylvania” that identified black bears as “a very influential predator on fawns there.”

The study, done in 2002 by Penn State graduate student Justin Vreeland, found that 32.7 percent of fawn fatalities resulted from bear predation, while 36.7 percent resulted from coyotes. The report concluded, “in heavily forested regions of Pennsylvania, where black bear densities are great, black bears may be at least as efficient predators of fawns as are coyotes.”

Cross cautions against jumping to conclusions, though. “Pennsylvania’s bear densities are not all that different from ours, but – and this is a very big ‘but’ – their deer densities are much higher than ours, especially in northern Maine,” Cross says.

He explains that a bear is obligated to maximize its energy intake versus its energy expenditures as it forages for food. The bear has to eat intelligently while not burning too many calories trying to get that food.

“I think it probably makes sense for bears in Pennsylvania to conduct themselves in a manner that increases their potential to encounter fawns while they are young and vulnerable,” he says. By contrast, a bear in northern Maine, where deer densities are extremely low, wouldn’t be likely to adopt such a feeding strategy because fawns aren’t abundant enough to rely on. “A bear encounters a fawn by chance – and not often,” he says. “With very low deer densities, bears would have much less impact on the deer population than other predators.”

But the lack of hard data makes the relationship difficult to understand. And as the state wrestles with ways to improve the deer herd, bear management overlaps with deer management as biologists wonder if reducing bear populations would result in more deer. A well-designed fawn predation study would be the best way to assess the impact of bears and the potential effectiveness of managing against bears and in favor of deer. But such a study would be difficult and expensive.

Another approach would be to reduce bear densities in a particular area and see if the deer harvest increases in relation to similar areas with no bear density reduction, but there’s no scientific precedent for success with this type of experiment. “You may simply end up with low bear and low deer densities,” said Cross.

At the moment, managers are taking a wait-and-see approach, which makes collecting good bear population data even more important. In two of Cross’s three study areas, bear population numbers are heading upwards. Deer numbers, meanwhile, have dropped in all three. “I don’t think the two events are closely associated, largely because our bear density has increased far less than the deer densities have decreased,” he says. “A 10 or even 20 percent increase in bears should not decrease deer numbers drastically.”

Cross’s colleague, Inland Fisheries and Wildlife biologist Shawn Haskell, agrees. “Reducing bear densities might save a couple fawns per square mile each year, but how meaningful is that, and are there easier or more effective ways to boost deer populations?” he asks.

Blood work collected from bears over the past few years has shed additional light on – and raised additional questions about – the bear/deer relationship. Dr. Rita Seger, a researcher at the University of Maine, studied a specific stable nitrogen radioisotope in the blood that allowed her to determine what percentage of the bear’s protein came from animal sources versus vegetation.

The bloodwork showed that animal sources of protein were highest in the area that appeared to have the most deer, but according to Cross, that area also had the most beaver, another potential source of meat. Carrion and even ants can’t be ruled out, because the bloodwork is “based on trophic level, and the actual sources can’t be determined with accuracy.”

“Many interpretations of the data may be applied,” Cross says. It is clearly just enough information to make you wonder.”

Counting Bears Image

Photo courtesy of the Maine Dept. of Inland Fisheries & Wildlife Collections.

Springing into Action

On the Studmill Road, Rudolph finally comes buzzing into view on his four-wheeler, flashing the thumbs-up as he crests a hill. “We got one,” Cross says, tapping out his pipe. He and his team mobilize into two pickups to follow Rudolph back into the woods.

Rudolph later explains that he found the bear in the first trap he had checked that morning. “I could see it from the road. I could just see its ears sticking up,” he says. “I had to go check the rest of the sets, though, before I came back to get everyone.”

Rudolph leads the team off the road into a stand of tall hemlock and spruce trees. The ground, spongy underfoot, is littered with moss, fir needles, rock outcroppings, and felled branches. They have to watch for moose droppings. Then doughnut crumbs and fish skeletons appear – the remains of the bait – accompanied by the pungent scent of the lure, smeared in a paste on a couple of tree trunks.

The bear – which the biologists will later measure as a 120-pound male – hunkers down in a small dip in the uneven ground. A thin steel cable, wrapped around its left forepaw, keeps it tethered to a tall hemlock. Cross has set snares at this location for years, and the hemlock bears the scars of other ursines who’ve clawed and bitten at its bark.

“When the bear trips the snare, it snaps tight around his paw without actually hurting it,” Cross had explained earlier in the day. To demonstrate, he stuck his own arm in a snare to trigger it. The steel cable slipped neatly around his forearm. “The more they struggle to escape, the tighter it gets,” Cross says, although he points out a metal stop on the snare that prevents the cable from cutting the skin or affecting circulation.

Although the bears settle down eventually, they sometimes panic when people approach. Some bears charge. Some try to scoot away. Some, like this one, make soft whimpering noises and try to demonstrate their submissiveness.

To minimize the bear’s distress, team members keep their distance while biologist Dan Wagner circles around and tranquilizes the bear with a syringe at the end of an eight-foot aluminum pole. The tranquilizer, Cross explains, is “mixed specially to provide for the greatest safety and welfare of the captured bear.”

Ten minutes later, after the bear has fallen asleep, Cross and his team get to work. He estimates the bear to be two years old, but he removes one of its teeth for analysis. Just as the rings in a tree trunk reveal a tree’s age, a tooth can reveal a bear’s age.

“This is the time of year these young bears are moving through new terrain,” Cross says. “They’re breaking away from their mothers and striking out on their own, bouncing around. This one could’ve been born right around here or 30 miles from here.”

In fact, young adult males range widely in their first few years, sometimes traveling as far as a hundred miles before settling down. Even then, their ranges may cover up to a hundred square miles. Females, meanwhile, generally have a range between six and nine square miles, typically staying close to the areas where their mothers lived.

When Cross’s team snares a female, they fit her with a radio collar so that they can keep track of her movements. Males, like this one, get a pink tag clipped onto each ear. Cross will also tattoo the tag number on the inside of the bear’s left lip. The ID will allow biologists to identify the bear if it’s ever harvested, involved in a nuisance case, or hit by a vehicle.

By the end of the season, biologists will make 72 captures. “That’s 8,165 pounds of bear,” Cross later says. The catch is down from 99 bears the previous year and about the same level as in 2008.

The biologists weigh and measure the bear, take its temperature, and do a brief physical. Cross points out scratches on the left side of the bear’s head behind the eye and beneath its jaw.

“Another bear probably got after it at some point,” he says. “As these smaller ones move through new areas, they get chased by other bears. They’re not gentle with each other. In another three years, if everything goes okay for him, he’ll finally be big enough to throw his weight around.”

The crew takes a few more notes along with a few pictures and then withdraws to the road, leaving the bear to wake up on its own. “It probably has another 40 minutes before it sleeps it off,” Cross says.

There’s no rest for the bear team, though. It’s just shy of noon, and already they’ve put in a full day. Back at the truck, they stash their gear and get their assignments for the afternoon. Cross spreads a map across the hood of his pickup, and his team gathers around. They’ll strike out separately to check for hits on prebaits, reset snares, and set new snares.

Around six, everyone will straggle back into camp. They’ll have stories to swap, numbers to crunch, paperwork to finish. They’ll cook dinner and eat, check their gear for morning, go to bed. Night will settle in thick among the pine trees. An owl will call, and another. Maine’s black bears, like darker patches of night, will be on the move.

Cross hopes he’ll meet a few of them in the morning. In fact, he’s counting on it.

A former resident of Maine who spent plenty of time in the northern woods, Chris Mackowski now teaches in the school of journalism and mass communication at St. Bonaventure University in western New York.

 
Discussion

No discussion as of yet.

Join the discussion

To ensure a respectful dialogue, please refrain from posting content that is unlawful, harassing, discriminatory, libelous, obscene, or inflammatory. Northern Woodlands assumes no responsibility or liability arising from forum postings and reserves the right to edit all postings. Thanks for joining the discussion.

Please help us reduce spam by spelling out the answer to this math question
five plus five adds up to (3 characters required)