Idaho biologists find, monitor wolf pups
The wolf pup had downy fur and a chubby little belly. But as it bolted from the den, it already showed signs of an adult wolf’s fleetness. Lacy Robinson was close behind, but not quick enough. After a scramble through the brush, the pup disappeared into the dense forest of the North Fork of the Coeur d’Alene River drainage. Robinson returned to the den, where seven wolf pups remained to be outfitted with tiny radio collars.
“Maybe if it was an equal footrace,” she said with a rueful sigh, noting that the wolf pup had the advantage of ducking under fallen logs.
Chasing pups is part of the job for Robinson, one of the lead biologists on wolf pup studies for the Idaho Department of Fish and Game.
This spring, department biologists have collared 27 wolf pups from seven packs around the state, using methods Robinson developed. The work is part of efforts to track wolf behavior and survival rates during their first year of life.
It’s cutting-edge research, said Jim Hayden, the department’s biologist for wolves, bears and lions. Knowing how many young animals survive their first winter helps biologists monitor whether wildlife populations are trending up or down. Yet aside from a handful of studies in Canada and Minnesota, little research has been conducted on pup survival.
“It’s one of the more poorly understood aspects of wolf biology,” said Dan Stark, a large carnivore specialist for the Minnesota Department of Natural Resources not involved in the Idaho research.
Reliable data on pup survival is particularly important in Idaho, where pups born in April are legal to hunt when wolf season opens at the end of August, said Suzanne Stone, Defenders of Wildlife’s Northern Rockies representative.
“Pup survival is a great indicator of how healthy the overall population is,” Stone said. “This should help inform wolf managers … when it comes to setting hunting seasons and conservation goals.”
‘They’re not happy’
Getting that information has Robinson crawling into wolf dens, designing lightweight radio collars and imitating a pup’s whine. It’s an ideal job for the 36-year-old biologist, whose résumé lists a decade of professional field research.
“I get excited about all the data we will get from those collars,” she said.
On a recent morning, Robinson led two other biologists to the suspected den site of the Bumblebee pack in the North Fork of the Coeur d’Alene River drainage. Last summer, she found the empty den after a wolf pup was spotted in the area. This year, the biologists were returning in hopes of finding blue-eyed pups to collar.
Anticipation built as the crew hiked into a narrow canyon. Fresh scat indicated the den was probably still in use, and a shaded patch of snow held a tiny paw print.
The three biologists crept through an alder thicket, careful not to let branches scrape against nylon backpacks. Adult wolves are generally relaxed around den sites, said Robinson, who has approached within 15 feet of one without it noticing her. But suspicious noises could alert the adults, who would immediately try to move the pups to a new location.
“Wolfy,” Robinson whispered about the atmosphere, as the group reached the creek bottom. A hemlock canopy filtered the light, and the bleached bones of an old kill were scattered along the stream bank. Robinson peered inside the den, located beneath the intertwined roots of two ancient cedar trees. Two wolf pups snoozed near the entrance. One pup’s leg twitched in its sleep.
As the pups woke up, they stared at the intruders with still-developing eyesight, lifting tiny muzzles to sniff the air. Robinson had covered an escape route at the back of the den with a backpack, but one pup darted out through another bolt hole.
After giving up the chase, Robinson made puppy noises, trying to coax the pup back to the den. The whines caught the attention of an adult wolf, which trotted toward the den site with a bone for the pups to play with. It dropped the bone when it saw the biologists, melting back into the trees.
Unlike bears and moose, wolves don’t actively defend their young. But the hillsides soon rang with alarm barks that ended in mournful howls. “They’re not happy,” Robinson said, as she prepared to crawl inside the den.
Collaring, testing cheaper alternative
At 5-foot-4, she’s agile enough to squeeze into spaces intended for female wolves. After crawling through a narrow slit, the den opened into an area that was large enough for her to crouch in, bigger than most of the dens she’s been in.
In the tight quarters, “I stay calm and focused,” she said. Claustrophobia aside, the smell can be overpowering. Wolves’ all-protein diet gives their scat a pungent, rotting meat odor.
Robinson worked quickly in the den, putting the seven remaining pups into canvas laundry bags and handing them out to wildlife biologist Laura Wolf and technician Casey McCormack. The dark, enclosed space kept most of the pups quiet, though two clawed and bit at the canvas. “Future alphas,” the biologists remarked.
At 4 to 6 weeks old, the pups were a sturdy 11 to 13 pounds each, with fuzzy gray fur, tawny markings and ears that twitched inquisitively.
McCormack slipped a face mask made from a sock over each pup’s muzzle to keep it calm while he inserted ear tags and attached radio collars. He also took saliva and blood samples for DNA before releasing the pups back into the den.
Robinson worked with a Minnesota company on the radio collars, which use transmitters designed for tracking fish. The pleated collars weigh less than 3 ounces each and expand as the pups grow.
Besides the radio-collaring, Robinson is working on efforts to monitor wolf pups through DNA. Gathering saliva and blood samples at den sites allows researchers to identify individuals through genotyping. When the pups get older, researchers will return to the pack’s rendezvous sites for DNA in scat samples, learning which individuals are still with the pack.
Both the collaring of pups and the DNA collection are less costly than outfitting adult wolves with radio collars, Robinson said. Trapping adult wolves can take weeks of labor-intensive efforts, and using a helicopter to locate and dart adults so they can be collared is also expensive.
Young wolves likely an easier target
This is Idaho Fish and Game’s second year of outfitting pups with radio collars. Last year, Robinson collared 15 pups from two North Idaho packs. Five are still alive; seven were killed by hunters and trappers; and three died of unknown causes.
With such a small sample, it’s hard to draw conclusions, Robinson said. But the less-wary pups appear to be an easier target for hunters and trappers than adult wolves.
Besides being more naive than adults, young animals typically represent a large percentage of the wolf population, which also explains why they show up in high proportions at harvest, said the Minnesota DNR’s Stark.
In Minnesota, “we age all the wolves taken by hunters and trappers,” he said. About half are less than 2 years old.
As a research biologist, Robinson said she’s trained to focus on wildlife at the population scale, not the fate of individual animals. So, when pups are killed by hunters or trappers, and ear tags and radio collars are turned in, “I see it as really important information that will help us monitor and manage wolves,” she said.
As Robinson left the den site, she paused to howl twice.
The adult wolves, which had fallen quiet, resumed the deep-throated barks that ended in howls. Unseen eyes watched as the biologists hiked out of the canyon.
The adult wolves would return to the den to gather the pups, including the one that bolted away. They’d be taken to a new location, one of several denning sites in the area.
“You only get one chance to collar pups,” Robinson said. “As soon as we’re gone, they’ll be moving them.”