TORTOISES AND CANINES

Tortoises are land-dwelling, high-domed turtles that range over the Mojave and Sonoran deserts. The desert tortoise is an herbivore that may attain a length (upper shell) of 9–15 inches. This is a long-lived species that is slow to reproduce. The flattened front limbs are well adapted for digging burrows, and a single tortoise may dig a dozen or more burrows distributed over its home range. Tortoises are thought to spend up to 95% of their lives underground, enabling them to escape predators and desert temperatures that can exceed 140°F in summer or dip below freezing in winter.

When a tortoise dies, its shell may remain and leave behind clues to the age of the tortoise and, even in rare cases, the cause of death. By studying these shells, scientists attempt to estimate mortality rates. Based on such evidence coupled with other studies and monitoring activities, scientists have determined that populations of the Mojave Desert tortoise have been declining since the 1970s. Information on high-mortality rates resulted in the temporary federal emergency listing as "endangered" in 1989, and the official listing as “threatened” in 1990.

Natural predators of the desert tortoise include ravens, gila monsters, kit foxes, badgers, roadrunners, and coyotes, which prey on the 2–3-inch juveniles that have thin, delicate shells. Primary threats outside natural predators include illegal collection and vandalism by humans; destroyed habitat; upper respiratory tract disease; and loss of forage plants, or food, due to invasive plant species and competition with grazing livestock.

There is a long history of dogs working with humans to locate specific targets of interest, for example, drugs, explosives, accelerants, natural gas leaks, illegally poached wildlife, live humans, human remains, termites, and forensic evidence. Several recent high-profile searches where handler/dog teams were deployed include the Columbia space shuttle disaster and 911 terrorist attacks. In both instances, these missions involved the recovery of human remains. In the summer of 2003, dogs assisted in locating historical and previously unknown gravesites of the famed Donner Party in Truckee, California.

There are reasons why dogs are so successful at such tasks. Dogs possess a remarkable sense of smell and the ability to communicate what they smell to people. The sense of smell in the average dog is thousands of times more powerful than in humans. It follows that partnering dogs and humans is a natural approach to overcoming barriers that humans alone face in surveying the populations of the Mojave Desert tortoise. However, even with a keen sense of smell, not just any dog can become a “specialist.”

First, and most importantly, the dog must have a high level of “drive,” or motivation to work. Drive is often confused with high-energy, out-of-control behavior and considered a defect in a pet. Working dogs possess different types and combinations of drive—such as prey, play, hunt, and food. Cablk selects dogs for play and hunt drives only when seeking appropriate wildlife detection dogs. This combination of drives motivates the dog to continue searching for tortoises after long hours in the field and, upon finding one, immediately switch focus to the handler, who carries the toy reward. In this manner, the dog is fanatic about finding the tortoise, but after it does, it ignores the tortoise completely. Because tortoises are federally protected, ensuring their safety was a primary concern throughout the pilot project. Dogs that find tortoises must resist all temptation to interact with the tortoises directly, which can be difficult given the soccer-ball shape of adult tortoises!

To become a working dog, a canine must be fit, agile, and temperamentally sound enabling it to work in difficult terrain for long periods. For tortoise detection, both dog and handler must be athletes and possess a special ability to communicate clearly and consistently with each other.