Alaska Fish & Wildlife News
Dec 2014

Wolverines: Behind the Myth

By Riley Woodford

caption follows

Wolverine release: This wolverine was collared and had only recovered from the immobilizing drug.

The wolverine'due south reputation precedes it.

In Mark Trail'southward Book of Animals, Ed Dodd writes: "Savage ferocity combined with mischievous cunning has made the wolverine an object of detest and dread amidst trappers."

In Mammals of Due north America, Vic Cahalane recounts the legendary prowess of the wolverine as fact: immensely strong and known to drive bears and mountain lions off their kills (two or iii at a fourth dimension, fifty-fifty); capable of taking down a bear in a fight; and bad-tempered loners that will destroy a cabin out of sheer deviltry.

Fact and Fiction

Fish and Game researchers Howard Gold and Mike Harrington are studying wolverines in South-central Alaska. In contempo years they've captured 18 wolverines and equipped them with GPS tracking collars to meliorate understand their movements and numbers. Wolverines are impressive, but much of the reputation is exaggerated.

"They've got such a bad rap," Harrington said. "I've had people ask, 'will they hunt you lot downward? Aren't they dangerous?' People wonder if we're afraid of them."

"A lot of myths about them are way overblown," Golden said. "People attribute magic powers to them, simply they're just doing their thing, looking for food. They are curious, smart animals and they effigy stuff out pretty quick. They are smart enough to run down a trap line, and that'll make trappers mad. But it makes sense that they'd do that – there's e'er food on these trap lines. They're not extra aggressive, they avert trouble."

Wolverines are weasels, Golden said, and have the weasel nature. "That whole family is pretty like, only the size is different. Ermine can be bold; weasels are an intelligent family of animals and they know how to survive."

While wolverines are usually alone, the "bad tempered loner" stereotype gives the impression they are downright hating. Aureate visited a facility in Washington that's home to nearly twoscore wolverines. They shared a large common area and he said they were quite tolerant and social with each other.

"If resources are limited that tin cause conflict, but they tin be social," Gilt said. "If nutrient is plentiful, they've got no reason to worry about each other. We've seen them in April from the air wrestling and playing with each other, they weren't fighting, they're socializing."

They are territorial, in the general sense of the word, but Harrington and Golden use the term "home utilize area" to depict the area they favor. "They pick areas they maintain and go along to themselves, males volition overlap with females, simply males don't overlap much with males, or females with females," Harrington said. "They need resources, and they option an area where they can brand a living and survive."

They accept scent glands, a ventral gland near the belly button, anal glands, and they as well have picayune scent glands on the bottom of the pads of their feet, and when they walk they leave smell. They as well scent-mark through urination. "They basically maintain territory this way through active marking," Golden said. "We have found some that have been in fights and are scarred up, they do get into tussles. "

He said a wolverine can defend itself pretty well, but it's no match for larger predators.  "Ii wolves can kill one," he said. "You lot hear stories about them chasing bears off, I've never seen that happen, or known anyone who has."

caption follows

Mike Harrington holds a young female wolverine. Wolverines are sexually dimorphic; males are about 30 percent larger than females - 30 to 40 pounds compared to females in the 20 to 25 pound range. This female, CWF006 has a bluish ear tag and was pregnant when she was defenseless on March seven, 2012. In this picture she had simply been recaptured to retrieve her collar and is virtually to be released.

Their eyesight and hearing are not especially good, but they have an outstanding sense of smell.

"They've got a pretty proficient set of tools on them; a really good nose, they can aroma food over long distances or buried well under the snow," Aureate said. "They can climb trees. They have a really warm coat. They've got strong claws for excavation and defense, and incredibly strong jaws for biting and crushing os and frozen meat - non the aforementioned burdensome ability as a wolf, but they're non as big, a big wolverine is xl pounds and pocket-size wolf is 60 pounds."

"You await at them, they're generally built for scavenging," Golden said. "Just they're very opportunistic and regularly kill modest game. They're non as fast equally wolves, and they don't work in packs, just they tin be more predator than scavenger if the situation allows for it."

Wolverines hunt snowshoe hares and voles, and in summer ground squirrels and marmots are important casualty items.  "Nosotros've got documentation of them killing smaller Dall sheep. In Scandinavian countries they lose domestic sheep and reindeer to wolverines, and the regime provides compensation to herders. The herders are required to hire rangers to certificate wolverine den sites and reproduction, and that's one reason they have great reproductive data."

It is true that wolverines are very potent for their size and have incredible stamina. Golden said a wolverine tin can embrace 30 miles in a night, working a circuit in search of food. They will den upwards and rest for brief periods, and then become back on the move.  That power to travel through incredibly rugged mountainous terrain is non exaggerated.

"That's the large thing to come out of the GPS work for Mike and I, and information technology's pretty amazing when you see it," Gilt said. "We get locations every 20 minutes, you can see how fast they movement around terrain, they go up and down really steep, icy, rocky slopes like they're not even there. You could never hike it – y'all'd need climbing gear. It's like they meet the earth every bit two-dimensional, the way they motility upward and down these snow-covered slopes."

Tracks in the snow

An innovative technique to assess population size has partly driven the inquiry. ADF&Grand biometrician Earl Becker adult a method to estimate wolf populations based on aeriform surveys of tracks in snow. Called SUPE, Sample Unit Probability Figurer, Becker worked out the technique for wolves and he worked with Aureate and Harrington to apply it to wolverines. Given some bones assumptions, information technology works like this: biologists survey an surface area after fresh snowfall and identify sets of tracks. The rail lines can exist extrapolated to population numbers. Some basic assumptions must exist met, for example, all animals of interest move during the written report, tracks are continuous, they're recognizable from the air, and pre and post snowstorm tracks can be distinguished.

Wolverines behave differently from wolves, and they don't run in packs. An important departure is that a wolverine may sometimes sit down tight for two or three days, in a den site or on a kill, and that needs to be factored in.

caption follows

Howard Golden fits a collar on a captured wolverine. Photograph by Isabelle Thibault.

"For two or three days out of twenty they might not exist moving, and if we did a SUPE at that time we might miss 10 or fifteen percentage that weren't moving after a fresh snowfall," Golden said. "That's a correction factor nosotros need to apply to the calculated estimate."

"The other matter about SUPE, it only works in some areas," he added. "It wouldn't piece of work in Southeast; the canopy encompass is too thick. You lot have to come across that ready of assumptions, and commonly we can verify them while nosotros're flying."

Collaring and tracking wolverines allowed researchers to basis truth the technique – and learn a lot about wolverines in the process. Results from a cooperative report with Chugach National Forest indicated a wolverine density of 4.five to five.0 wolverines per 1,000 square kilometers in Kenai Mountains and Turnagain Arm surface area, which is typical for other areas of Due south-cardinal where SUPES were conducted.

"Different techniques are suitable for certain areas," Golden said. "In some areas you're just looking for occupancy – do we fifty-fifty have wolverines?"

The researchers pointed out two other methods used to written report wolverines. Hair snares subtly snag a tuft of fur from a passing animal, and the Deoxyribonucleic acid in the follicles enables biologists to identify individual animals, their gender and relatedness, and multiple samples over time can provide a population estimate (mark-recapture). Photograph identification uses remote, motion-triggered trail cameras to photograph animals in specific poses that reveal distinctive markings that tin place individuals – much equally tail fluke marks are used to identify humpback whales.

Catching wolverines: traps and darts

The researchers captured 18 unlike wolverines between September 2007 and March 2014. Including recaptures, animals were alive-trapped 14 times and helicopter-darted 10 times. Amid the 18 wolverines captured, there were 5 juvenile (1–ii years old) females, five adult females, four juvenile males and four adult males. Wolverines were captured in the Chugach Mountains east of Anchorage (in the state park), on the Elmendorf-Richardson joint base (JBER) and south of Anchorage in the Kenai Mountains. The capture piece of work was done in cooperation with Chugach Country Park, JBER Natural Resources Department, and Chugach National Forest.

Three wolverines did not yield data – they slipped their collars right abroad, or for some other reasons researchers were unable to detect signals. All the telemetry piece of work was done in tardily winter and early bound to better empathise how wolverines movement during the menses when SUPES are conducted.

Cameras proved to be a valuable tool for trapping and darting. Motion-triggered trail cameras were gear up up near the live traps, and researchers wore helmet-mounted video cameras when helicopter darting to help them acquire from capture attempts. That helped them solve an equipment malfunction at one point in the projection - they slowed the video downwardly and watched it frame by frame, revealing a trouble with the dart design they were able to correct.

Darting tin can be really efficient under ideal atmospheric condition, and Gold said one day they caught four wolverines. That was exceptional, some days they constitute wolverines they couldn't grab. Aircraft searched for roaming wolverines, and and so chosen the capture team.

caption follows

This Google Earth 3D map shows the movements of 2 wolverines through the upper slopes and summits of the rugged Chugach Mountains. CWM006 is a male, and the scarlet line shows his movements over virtually a month, between his capture and collaring Feb. 21, 2013 and his final transmission March 26, 2013. The blueish line shows the movements of CWF008, a female captured March 2, 2013 and her last transmission June 12, 2013, about a three-calendar month menstruation.  "This is how they really piece of work in the 3-dimensional globe," Harrington said. "You really get a good appreciation when you lot see how steep it is and how they go upwards and down that rugged stuff."

"Wolverines are never very abundant, even when they're abundant for the species," Golden said. "You need good weather to rails them, we had two fixed-wing aircraft but looking for animals, sometimes for hours, and so we're sitting on a ridge with the helicopter, waiting. Then nosotros get the telephone call and go afterward them."

Darting a moving animate being from a moving helicopter is clearly a challenge. Harrington said the mountainous terrain and relatively pocket-size size of the target added to the difficulty. One thing played to their advantage, he said when pursued, wolverines tended to run uphill. In deep snow that actually hampered their speed.

"On hard packed snow, we couldn't believe how fast they tin can run," he said.

Pursuit was limited to 10 minutes. "Sometimes we had to say, 'we're not going to get this guy.'"

Once caught, wolverines were apace processed. Throughout processing biologists monitored wolverines' temperature, heart rate and respiration, and were prepared to provide supplemental oxygen if needed. They took samples of tissue (for Deoxyribonucleic acid), hair and blood, the animals were weighed and measured, age estimated, and they were marked with an ear tag and equipped with a GPS/VHF collar.

The collars were programmed to tape GPS locations at xx-min intervals, and were capable of maintaining that rate of information drove for near 3 months then to keep VHF beaconing for nearly 100 days longer before bombardment failure. Collars as well stored altitude and air temperature. Two types of GPS collars were used; both stored thousands of location data points onboard and allowed remote downloading of neckband data from the ground or from the air. 1 model could be released remotely to driblet-off, the other could not and required recapture to retrieve collars.

Gold and Harrington were successful alive-trapping on JBER during the commencement two or three years while new animals were nonetheless coming into the trapsites. The researchers took advantage of a wintertime moose hunting season on the articulation base - wolverines were attracted to impale sites and worked the hunt areas into their foraging circuits. All the same, information technology became very difficult to attract wolverines into traps during winter of 2012–13, which they attributed more often than not to the lack of new wolverines visiting the area. From images gathered on the remote cameras, information technology seemed the animals were likewise wary to be caught.

"They remember where they've found food, but they got wise to the traps really quick," Harrington said. "They're hard to live trap in the first place, and actually hard later that. You lot might fool them once, but how do y'all fool them again after that? We got creative with different kinds of allurement - we tried chickens wrapped in bacon, and big wads of beef suet."

Wide ranging

Home range estimates for wolverines in Southward-fundamental Alaska testify females utilise about 300 to 600 square kilometers (115-230 square miles) and males use nigh 700 to 1,000 square kilometers (270 to 380 square miles.

caption follows

Movements of 11 wolverines in the Chugach Mountains due east of Anchorage, and i wolverine on the Kenai Peninsula further south. Turnagain Arm is the h2o in the centre left. Adult male CWM007 is depicted in cerise and has a home use area twice the size of other wolverines. Note the movements of the male (CWM006) and female person (CWF008) every bit shown on the other map of the mountain tops.

Males and females traveled extensively throughout their home employ areas. Both sexes occasionally went on exploratory trips and so returned to their primary areas. A look at the movements of five wolverines over the course of a yr (2 females and three males) showed great variation in distances traveled, some days they covered a lot of ground, others days not so much. The average distances traveled per day was nearly 12 kilometers for the females, and betwixt viii and 21 kilometers for the males.

 "One male had twice equally large an area as other wolverines," Gilded said. "It may be that area had lost a male and this brute just took over the whole area, at least for the curt fourth dimension the collar was active."

Considering the focus of the study was movement in belatedly winter and jump, the researchers did not rail wolverines twelvemonth-circular. The far ranging male did provide some data in late leap – when he expanded his range fifty-fifty more.

"They do spend a lot of fourth dimension in summer during the breeding flavor testing boundaries and trying to encounter females," he said.

An important fourth dimension in a wolverine'south life, and a time for significant movement, is when a young developed strikes out to found its ain home range. Wolverines are born in February or March, ii to four kits that unremarkably dwindle from mortality to one or two past autumn.

"Mortality is pretty high for kits," Golden said. "We're finding females generally don't have a litter before they're about three years onetime, and then typically accept a litter about every other year."

The kits are essentially full grown by Oct or November and brainstorm moving out. It can exist tough for a young wolverine to find a territory that is unoccupied and suitable.  "A girl might stay with mom a couple years and inherit her area," Golden said. "Young may try and stay relatively shut to their natal area, and siblings may exist more tolerant of each other."

Just wolverines have been known to disperse equally far as 235 miles. Dispersal is important, that's how wild areas that "produce" wolverines tin can supply them to potential dwelling house ranges elsewhere, expert habitat where wolverines may have been harvested.

That balance is a model for sustainable yield – enough refugia from human action, good habitat for wolverines that are producing young that volition emigrate out.

Hunters and trappers in Alaska harvest about 550 wolverines each twelvemonth.  Because wolverine reproductive potential and survivorship is low information technology'southward of import to understand where and when animals are harvested to be certain the population is non overharvested. Wolverines disperse depending on availability of food and habitat resource, and animals dispersing from areas where they are not trapped replenish the population in areas where they are hunted and trapped.

A gallery of trail camera photos of wolverines is available, likewise as a brusk video of a wolverine raiding the nest of a ground-nesting shorebird and eating the eggs.

Riley Woodford is the editor of Alaska Fish and Wild fauna News.

Receive a monthly notice most new bug and articles.