Canines have a long and intimate relationship with bones, but those trained and deployed by the nonprofit Institute for Canine Forensics (ICF) take that relationship to an entirely new level. While search-and-rescue and cadaver dogs are trained to find living and deceased humans, respectively, Human Remains Detection (HRD) dogs specialize in identifying bones and cremated remains (cremains). Most recently, their skills have been on display in the wake of California’s catastrophic 2018 fire season.
Driven by years of drought, fire suppression and a warming climate, western wildfires (including those in California) are starting earlier, burning hotter and lasting longer. And as increasing numbers of people make their homes in the state’s beautiful but high-fire-risk forests and wildlands, the human cost of these conflagrations has risen dramatically. California’s Carr, Camp and Woolsey fires were among the largest of the 8,527 wildfires that burned almost 2 million acres of land during the state’s wildfire season; these three fires alone destroyed more than 16,000 buildings, the majority of them homes. Many owners had only minutes to collect their families and run, leaving their possessions to be consumed by the flames.
Once the fires were out, ICF volunteer teams began helping those who’d lost everything recover one of their most precious possessions: the cremated remains of their loved ones. Considering fire’s destructive capacity—wildfires can burn hotter than 1,500˚F— it seems as though anything as fragile as cremains would be obliterated. Nonetheless, HRD dogs are able to sniff out even the faintest trace of their targets amongst the ashes.
On-site, ICF dog-and-handler teams sweep the area where a home once stood, working carefully and slowly. The dogs move back and forth, sniffing for any trace of cremains. When a dog sits down, the handler knows they’ve found something. If a second dog also points out a particular spot, volunteers begin a meticulous search through the ash and rubble.
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Protected by hazard suits and filter masks, they scrutinize the identified area for material with the distinct color and texture of cremains. As part of the search process, the GPS locations of places the dogs alert to are recorded so others may continue looking even if the initial search is unsuccessful. The ICF estimates its success rate to be more than 90 percent.
On the face of it, it’s hard to grasp how detecting ashes in an ash-covered landscape is even possible. To understand why it is requires a little explanation. Technically, cremains are not ashes but rather, ground-up bone matter. To cremate a body, it is placed in a furnace along with a small metal ID tag. After the organic material burns away, the bones are ground into a fine, homogenous gray-white powder and returned to the family, along with the identifying tag.
Fortunately for searchers, if they are found, cremains can be visually distinguished from house and furniture ash (finding the ID tag is an additional proof). The operative word is “if.” Dogs undertaking this task face a steep challenge: traversing fire wreckage without disturbing their surroundings while searching for a veritable needle in a haystack—or rather, a sewing needle in a haystack made up of embroidery needles.
To do this work, dogs go through an incredibly intense 18- to 24-month training regimen. Handlers begin by rewarding the dogs with treats, play or affection when they sniff a large human bone (donated for this purpose). They then teach the dogs to sit when they detect the smell and point their noses to its strongest source. Gradually, smaller and smaller bones, teeth and scatterings of cremains are used. Not surprisingly, graveyards are the best places to work on this training, as it helps the dogs learn that the smell comes from underground.
However, just being able to sniff out human remains and alert to their presence isn’t enough. Since these hardworking dogs operate in a variety of situations, they have to be ready for anything. HRD dogs are taught to remain calm in planes, cars, ATVs, kayaks and almost any other mode of transportation imaginable, and to be comfortable being held in their handler’s arms for extended periods of time. They are also taught to ignore any animals they come across, like snakes or mice, and to tolerate wearing special equipment, such as thick boots or reflective cooling vests.
The length of time HRD dogs work varies with the demands for their services. A typical work day averages four to six hours, during which they can cover anywhere from two to 10 acres of land, depending on its complexity, foliage, rubble and condition. Usually, they work three days, then are off-duty for one; they are also taken off-duty when ground temperature exceeds 100˚F or their internal temperature exceeds 104˚F (a dog’s normal body temperature ranges between 101 and 102.5˚F). The dogs’ welfare is their handlers’ primary concern.
Before California’s devastating 2017 fire season, ICF teams had primarily been involved in helping archeologists and builders identify prehistoric and historical burial sites, which is itself difficult and meticulous work. The organization’s Historic Human Remains Detection (HHRD) dogs are extremely good at their jobs and have successfully identified bones more than a century old.
HRD and HHRD pups have also been used to help find grave sites buried by landslides, unmarked graves or graves whose tombstones have degraded, as well as locations where migrants crossing the Sonoran Desert may have perished. In 2017, four ICF dogs helped investigate a remote Pacific island in hopes of finding Amelia Earhart’s remains.
Even in the rarified world of detection dogs, HRD and HHRD dogs’ skills stand out. How do they do it? Here’s a short refresher on canine olfactory skills: While the human brain is dominated by its visual system, dogs’ brains are mostly devoted to their noses. They’re able to sniff up to five times a second, and a fraction of each sniff travels into a bony structure called the olfactory recess, just above the hard palate, and connects to the vomeronasal organ, which is specialized for detecting scents. While there’s some evidence that humans have a nonfunctional version of this organ, in dogs, it serves as an auxiliary smell sensor and contains millions of scent receptors, roughly 40 times more than in humans.
Because scent molecules stay in the olfactory recess, stuck to olfactory receptors for long periods of time, dogs can follow scent trails for hours. Over time, the molecules accumulate, which allows dogs to detect them in concentrations as low as one part per trillion, or the equivalent of one drop of liquid in 13 million gallons of water. Dogs’ wet noses, or rhinariums, contain cold receptors that can identify the part of the nose that is experiencing the most evaporation due to air currents, allowing them to determine the direction from which a smell originates.
Any breed type can be trained as a HRD or HHRD dog, but some have a natural advantage. Dachshunds, for example, have 125 million scent receptors, whereas German Shepherds have 225 million and Bloodhounds have more than 300 million. Border Collies or Retrievers usually take to training more quickly, and those who can withstand extreme temperatures will perform better in harsh conditions. But it really comes down to the bond between dog and handler, as well as the unique personality of the dog.
For the last few months, at the request of individuals and families, ICF teams have been steadily working the ruins the state’s fires left behind. To date, they have recovered a total of 210 sets of cremains for 178 families, a service provided free to the requestor; travel, food and shelter costs were (and continue to be) borne by donations, or by the volunteers themselves.
Going forward, the ICF has expressed a desire for their service to become a more routine part of the post-fire process. Since fire victims are filling out paperwork for insurance anyway, it could be as simple as asking them to report if cremated remains were kept in the home and if they would like their recovery to be attempted.
The work done by these diligent dogs and their human partners can mean the world to someone who’s lost a loved one’s cremains, their last link to that person.