Tuesday, 11 December 2018
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Invisible thread links search dogs, quarry, owners

FAIRBANKS — Search and rescue dog trainers can’t see the invisible clues their dogs use to follow a scent trail, but in order to be better trainers they try to imagine how the dogs perceive them.

That’s why Cathie Harms took out a container of baby powder Saturday morning and released a puff into the cool, foggy air when her dog hesitated at the corner of 21st Avenue and a footpath off South Cushman Street. She hoped to get a sense of how the scent of fellow dog trainer Tyler Cunningham had dispersed in the faint wind in order to give some direction to Vickers, her 8-year-old German shepherd-border collie mix.

This part of the weekly PAWS Search & Rescue Dogs training exercise started a block away in the parking lot of the Tesco Lighting and Design Center. Harms put Cunningham’s sweatshirt in front of Vickers’ nose. “Check it,” Harms commanded, then, “Where’d he go?” 

The four dog trainer pairs at Saturday’s training took turns following the scent trail.  

Vickers followed Cunningham’s scent along the side of the Tesco building and along the sidewalk down 21st Avenue. But here at the intersection of the footpath, subtle changes in Vickers’ body language told her the dog had temporarily lost the trail.

“I’m looking for the head going up and down, the tail at a certain angle and following the nose instead of looking around,” Harms said.

The dog body language is far from obvious to an untrained handler and can be full of false positive and negative signs that the dog is on the trail. For example, a dog pulling steadily on the leash is a sign it’s following the trail. But some dogs pull especially hard when they lose the trail and are anxious about finding it again, Harms said.


Scent mystery 

Humans don’t fully understand the mechanism dogs use to follow a scent trail, but they still try to think like dogs by trying to visualize the scent. The baby powder helps with this.

“I imagine a cloud, and where it’s going to go is going to be affected by wind, by temperature, by relative humidity and so forth,” Harms said.

Dog trainers used to believe in a “raft” theory that dogs follow the column of skin cells that fall off humans every second. Subsequent research has shown that dogs aren’t tracking the skin cells directly because the cells are far too large to fit into the receptors in a dog’s nose. However, dead skin is still likely part of the equation, Harms said. A newer theory is that dogs are following the bacteria that feed on the skin cells.

Another tracking theory is that dogs are relying on the odor of crushed vegetation, but this doesn’t explain how a dog follows a scent trail across an asphalt parking lot. Dogs have demonstrated they can track someone who is carried by a pulley, whose feet never touch the ground, Harms said.

For whatever the reason, dogs have the ability to follow a path that someone traveled for roughly 24 to 48 hours after the person has passed — depending on the conditions. On Saturday, Vickers followed a scent that was two hours old.


PAWS Search and Rescue

The Fairbanks PAWS Search & Rescue organization incorporated in 1985 and contains a half dozen active dog/trainer pairs who volunteer when the Alaska State Troopers or other first-responder agencies request their help.

PAWS gets called for searches roughly 10 to 12 times a year, usually in wilderness settings. More recently, the organization has been called for more city searches, which is why Vickers and Harms practiced off South Cushman Street on Saturday, working their way past yards with barking dogs, discarded takeout food trays and other distractions as they followed their scent trail on 21st Avenue.

“Get to work,” Harms told Vickers when the dog appeared to leave Cunningham’s scent trail to investigate pee spots.

PAWS volunteers practice for about two hours almost every Saturday morning. In addition to training on scent trails, they also practice air scenting, which is an off-leash search for cadavers. On Saturday, that involved letting each dog loose in a small junkyard to find a coin purse with some human teeth and blood inside. To make it extra hard, Cunningham hid the purse inside a CONEX container, which kept the scent from dispersing widely around the yard. Then, in an indoor challenge, the dogs had to find a human knee bone and wrist bone hidden in a garage with a loft. The bones were completely dry, which added to the challenge.

“We’re talking about a 10-year-old bone, might as well be in a cemetery,” said one dog trainer, whose dog nonetheless succeeded in finding the bones tucked away in a bucket in a closet.

On the tracking practice, Vickers led Harms on a quarter-mile walk following Cunningham’s scent. After some backtracking, Vickers figured out that Cunningham turned left off 21st Avenue and on to the footpath. Vickers mostly kept to the scent trail, but another PAWS team member who knew the path Cunningham had walked interceded once when the dog wandered too far off the trail.

Vickers led Harms down Rickert Street and up 23rd Avenue back to South Cushman Street, where Cunningham was waiting for them in the parking lot of Variety Motors. As a reward, Vickers got his favorite toy, a tennis ball. For Harms, the reward is working in a team with her dog.

“There’s a lot of things you can do with your dog where you tell your dog what to do and they do it,” she said. “There’s a different level of partnership when the dog is doing something you can’t do.”


Joining PAWS

PAWS Search & Rescue Dogs is always looking for new members. They look for people who like the outdoors and don’t mind getting awakened at 2 a.m. for a search. Many different breeds/mixes of dogs can make good search and rescue dogs, but generally 30- to 60-pound dogs with double coats are well suited for Alaska work. Before they’re ready to train with PAWS, handlers need to train with Wilderness Search & Rescue, and dogs should have obedience and at least basic-level tracking training.

For more information, see the Facebook page: facebook.com/Pawsfairbanks.

Contact Outdoors Editor Sam Friedman at 459-7545. Follow him on Twitter: @FDNMoutdoors

Source: http://www.newsminer.com/features/outdoors/invisible-thread-links-search-dogs-quarry-owners/article_7df4ab64-de73-11e8-bec0-bf12b24cd8f4.html

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