Snaky Love

Radio Transmitters Implanted in Rattlers Reveal Maternal Instincts and Strange Mating Habits As a child, Dave Hardy was fascinated by snakes. He yearned to become a herpetologist, but he came from a family of doctors and eventually ended up as a Tucson anesthesiologist. His medical practice, however, did not diminish his interest in snakes. Whenever the busy doctor had a chance, he would hike into the desert to observe the reptiles. About 30 years ago, Hardy found an area particularly suited to his obsession-a stretch of high desert beneath the lichen-tinged limestone cliffs of the Chiricahua Mountains near Portal in southeastern Arizona. On these rugged slopes, amid the ocotillos with blood-red blooms, the sea-green agaves and the whitethorned acacias, Hardy became intrigued by the native black-tailed rattlesnake.

The doctor marveled at the snake's highly evolved physiology: flat heads with built-in heat sensors to monitor prey; creamy white underbellies; ochreand-umber geometry spilling off delicate spines; black tails that give way to rattles resembling ears of brown corn. All species of rattlesnakes have long been viewed as ferocious icons of the American West, animals that are better dead than alive. Hardy knew rattlesnakes are timid animals that rarely bite humans unless they are provoked. He always admired rattlesnakes, and the black-tailed rattlers were a stunning, remarkable species he wanted to study in the wild. "Rattlesnakes might have small brains, but they are complicated organisms with

SNAKE-OF-ALL-TRADES

The black-tailed rattlesnake (left), Crotalus molussus, grows to about 30 to 40 inches long and lives 15 to 20 years. It can climb, swim and detect infrared radiation with pits in front of its eyes, and it can change between sidewinding or straight movement.

Hardy never knew if the surgery troubled the snakes, but was heartened by the fact that when the newly telemetered rattlesnakes were released back into the wild, they would resume normal behaviors.

Hardy and Greene created a study area in the Chiricahua foothills. It was a 6square-mile swath of rolling hills cut by a creek bed lined by trees. For nearly two decades, Hardy, who is now 73, would hike the area with an H-shaped antenna attached to a receiver in a canvas bag. He carried with him his pencils, notebook and, in recent years, a Global Positioning System receiver. A gentle man with thick gray hair and lively blue eyes set beneath square glasses, Hardy would bound across the creek bed and up the rocky bank past wild grape and hackberry bushes. A hawk might scream from the sky, a white-tail doe might dart out of a mesquite thicket, but Hardy's ears would be tuned to his radio receiver. Each snake had a different radio frequency, and when the radio made a strong blip, blip, blip, blip sound, Hardy would know exactly which snake was near. He would

“discovery helps people care more about snakes,” Greene says.

They learned that a rattlesnake will become disoriented and starve to death when it is out of its home range.

“complicated behaviors,” Hardy says. “Humans have been on this Earth only about 150,000 years, and that's a pittance compared to rattlesnakes, which have been around several million years.” In 1984, Hardy met Harry Greene, a world-famous herpetologist and a professor in the Department of Ecology and Evolutionary Biology at Cornell University. The two friends began in 1988 to design and embark on studies to learn about black-tailed rattlesnake behaviors. The studies would last about 18 years and involve more than 4,600 observations of black-tailed rattlers in the wild.

Because Greene was based on the East Coast, Hardy conducted most of the fieldwork in Arizona. In all, he caught about 45 snakes, which he anesthetized in order to surgically implant radio transmitters.

To find the creature, observe it, take notes.

It was through this careful observation that Hardy and Greene learned that black-tailed rattlesnakes have sophisticated behaviors. For instance, male snakes try to court females with ritualized movements that entail a great deal of body-jerking. Females do not respond to the overtures unless they have gained sufficient weight to carry a litter. Although mother black-tailed rattlesnakes lose about 40 percent of their body weight and are emaciated and hungry after giving birth to live babies, they stay with their litters until the young snakes shed their skins and are better able to protect themselves usually about 10 days.

“I think our most dramatic discovery, made by Dave, was the parental care, and I have absolutely no doubt that such a Hardy and Greene learned that the black-tailed rattlesnakes are intimately familiar with their home ranges; that they return again and again to the places where they have met their mates or given birth or found ample supplies of food woodrats and other rodents. They learned that a rattlesnake will become disoriented and starve to death when it is out of its home range. Because of this, they believe it is wrong for humans to relocate snakes to a different landscape. It is, they believe, kinder to humanely euthanize a snake that humans consider a threat.

Also The two herpetologists are now writing a book about their findings, hoping that what they have learned about the behaviors of the black-tailed rattlesnakes of the Chiricahuas will help people know and respect these misunderstood creatures of the Arizona desert. Al