The Lethbridge Alberta Canada property advertised in a recent real estate listing was priced at $245,900, snakes included. The ancient river breaks, where prairie rattlesnakes not long ago hunted mice and gophers in the grass, had a much lower per-square-foot value before becoming part of the suburban promised land. Here, Herriot discusses how rattlers and ratepayers are making peace in Lethbridge.

"Custom built executive home in Paradise Canyon, overlooking the mountains and the river. Five bedrooms, four baths, lots of hardwood. Many extras."

LIKE RATTLERS IN THE PEONIES. The Lethbridge, Alta., property advertised in a recent real estate listing was priced at $245,900, snakes included. The ancient river breaks, where prairie rattlesnakes (Crotalus viridis) not long ago hunted mice and gophers in the grass, had a much lower per-square-foot value before becoming part of the suburban promised land.

As the Paradise Canyon subdivision was getting started, a sign trumpeted, "Welcome to Paradise." It was followed by a series of other billboards announcing a "championship golf course," a "planned subdivision," a "public restaurant"- all the suburban amenities. Each bore the development's logo, a stylized sun setting over stylized hills of green. The last sign, however, was the most interesting. It said only, "Watch for Wildlife," but it was much more than a simple reminder for motorists. It was also an announcement that urban rattlesnakes, with the blessing of municipal authorities, were here to stay. The City of Lethbridge had decided that a growing human population would not be permitted to wholly displace the snake population, so it set about educating its citizens, relocating "problem" rattlers and encouraging breeding. It is now also providing protected space and even buying up crucial habitat to remove it from development - all part of a comprehensive urban-rattlesnake management program that is unique in North America.

DEVELOPMENT, for a rattlesnake, is something that happens within and beneath. The pregnant female tucked away 10 metres from where we stand does not ask for much in terms of housing: a place where the sun warms her up in the morning, a rock for protection and shade on hot afternoons.

It is early August, 160 kilometres away from Paradise and the expanding city limits of Lethbridge. We are, in fact, a kilometre or more up a coulee on the south side of the South Saskatchewan River and just outside Medicine Hat, far enough beyond the gas wells and pivot irrigation plots for it to feel like prairie wilderness. If I crouch down and squint against the glare of sun on rimrock, I can just make her out in the dark: the small, spade-shaped head and one coil of her swollen belly. This is what Joel Nicholson and Kelly Kissner, non-game biologists with Alberta Fish and Wildlife, have taken me out to see: a pregnant female in her rookery.

"We found her here a month and a half ago under this exact same rock," says Nicholson. "She hasn't moved. Kelly palpated her at the time to make sure she was pregnant. The newborns will be born here a few weeks from now, if all goes according to plan."

And just in case such an abundance of maternal patience creates the wrong impression, Kissner, who did her master's thesis on the species at Saskatchewan's Grasslands National Park, is quick to dismiss notions of rattler nurture and motherhood. After their birth in late summer or early fall, the babies fend for themselves. "She will stay in their vicinity for a few days," she says. "You'll see a mother with her young shortly after the birth, but that doesn't really constitute parental care."

We can hear the sibilance of her rattle as we stand and talk snake biology. It sounds like locoweed seeds shaking in their pods, a grace note of late summer, when the birds have left off singing and the dried prairie vegetation hisses against boot and pant cuff.

After the female recovers from the exertion of giving birth, Kissner says, she departs for the hibernaculum, or winter den. Left behind, the babies usually shuck off their first skin within a week or so of being born. "That first shed is very fragile, and they have a little rattle. If you listen carefully, you can hear it, almost a buzz." I ask how they defend themselves, and Nicholson explains that they are venomous right from birth. Some poison on board and a set of keen sensory organs are all the help young rattlers get in finding food and a home in their first few weeks of life. They may cover up to half a kilometre of terrain as they search for a wintering site.

IT'S NOT EASY being a rattlesnake in Canada," Nicholson told me earlier as we prepared to head out of Medicine Hat into the area preferred by the cold-blooded rattlers. "They are at the margins of their thermoregulation capacities here [in Alberta]. They need good foraging habitat, but they also are limited by the availability of good denning sites. They've got to be able to get below the frost line to make it through our winters.

"It isn't the kind of species that can easily bounce back from a decline. Their reproductive potential is low. An old rattlesnake might live 15 years, but females only come to breeding age between five and seven years. And once they reach sexual maturity, they breed only once every second or third year. They produce between 4 and 12 young, and then there are high rates of mortality among the neonates. It's not a good numbers game."

Add to this set of challenges the difficulties implied in estimating populations of a creature that spends half its life underground and the rest hidden among rocks and vegetation, and you have everything required to keep conservation biologists awake nights counting snakes instead of sheep. In Alberta, where most of Canada's prairie rattlesnakes live, the species has two kinds of official status designations. Its "general status" is listed as "may be at risk," and its "detailed status" is "data deficient," which is to say that in the absence of information, scientists are feeling cautiously pessimistic.

THROUGHOUT SOUTHERN ALBERTA the problem of unwanted rattlers is on the rise. It has been a few years since someone shot up a den full of snakes, but the old fear and hatred of the pit viper persists. Urbanites still find it alarming to see a venomous creature in their gardens, even one minding its own business. And you still hear stories of motorists going out of their way to hit a snake on the road.

During our drive to the den site, Nicholson talked about human activities in the landscape that are making life more difficult for rattlesnakes. He pointed out shallow gas wells on either side of the highway. The well sites themselves are relatively innocuous. However, the traffic moving to and from wells on access roads along the rims of the river valleys kills a number of rattlesnakes, particularly in spring and fall, when they have to cross these barriers to make it from den site to forage zones and back again.

I asked about the irrigated cropland that we were driving through, wondering whether anyone was still plowing up native prairie to plant cash crops adjacent to the river. It happens, said Nicholson, citing a large expanse of good rattlesnake forage habitat that had been lost in the spring when a potato grower destroyed five sections, 1,295 hectares, of grassland to establish a new irrigation plot.

Yet the other growing threat to rattlesnake populations lies behind us, in the city itself, where smaller pieces of vital den and forage habitat are lost with every real estate or green-space expansion along the river valley. In 1949, Medicine Hat covered 13 square kilometres of river valley and adjacent landscapes. By 1998, that urban footprint had quadrupled. And continued expansion means more country residential zones near the city, including acreages along the river. In other words, Medicine Hat is facing exactly the pressures that gave rise to the rattlesnake program in nearby Lethbridge.

IT IS NOT SURPRISING that Lethbridge is leading the way; nowhere is the problem of urban encroachment on rattlesnake haunts more acute than on that city's edge, where Paradise Canyon and similar subdivisions have been swallowing up riparian and upland habitat at an unprecedented rate. Between 1950 and 1999, the Lethbridge footprint expanded from 7.8 to 51.8 square kilometres.

The man on call for rattlesnake relocation in Lethbridge is Reg Ernst, a former air traffic controller who decided he would study ecology so that he could turn his damage-control skills toward the management of a different set of departures and arrivals.

The day after my outing with Kissner and Nicholson, I was with Ernst, strolling down the fresh sidewalks of Paradise, past show homes where the attached garages stand out front as architectural testaments to our car-based culture. We were talking about roadkill rates. Since 1998, he said, roughly 20 rattlesnakes have died on the road into Paradise Canyon. "One year, there were seven or eight, and that was what really got us started.

"At that time, Fish and Wildlife officers would relocate problem rattlesnakes out in the country, where they most likely perished. The Helen Schuler Coulee Centre had been collecting information on rattlesnakes, gathering reports of roadkills and human/snake conflicts. Their concern for the fate of rattlesnakes in Lethbridge was the genesis of the whole conservation process."

Along with biologists from Alberta Fish and Wildife and a naturalist from the Lethbridge Naturalists Society, a researcher from the Helen Schuler Coulee Centre sat down at a table with representatives from the City of Lethbridge and the subdivision developer. Together, they conceived the city's rattlesnake response.

Early on, the group held an open house to survey attitudes toward rattlers in the city. Ninety-six percent of respondents expressed a desire to maintain a snake population within Lethbridge, while 93 percent approved the proposed conservation initiative. On the strength of that support, Ernst set to work.

JUST BEYOND THE EDGE of the subdivision, but still within sight of the mansions of Paradise, we stepped gingerly among basking snakes. Ernst was showing me their den site, a hibernaculum located less than 50 metres from property the city has slated for development in the next 5 to 10 years. Even with that impending encroachment, Ernst remains hopeful and goes out of his way to give the city credit for its support of the rattlesnake-recovery project. The source of his optimism was just ahead of us, as we continued along the riverbank into an urban nature reserve called Cottonwood Park.

Managed by the City of Lethbridge, Cottonwood Park is prime urban-rattlesnake range. Where other parks might have signs about litter and dogs, here the notices urge respect for the snakes. There is a station offering a brochure titled "Rattlers, People & Parks" and advising visitors what to do if they encounter a snake as well as how they can "help maintain Lethbridge's rattlesnake population" (see sidebar on next page). In 2002, Ernst tells me, the city saw fit to buy up a large piece of property adjacent to the park, in effect doubling the area of protected habitat. In addition to maintaining the park, the city funds the project's website and pays the wages of a summer ranger.

As we hiked down slopes overlooking a postcard sweep of valley, where cottonwoods spread their shade above the timeless turns of the Oldman River, Ernst talked about the objectives of the project: to educate the public, to increase their tolerance for rattlesnakes, to reduce the human-caused mortality rate, particularly roadkill, and to relocate "problem rattlesnakes" to more secure habitat.

After a final switchback in our trail, we were at the main feature in the protection strategy - a few square metres of hillside surrounded by a high chain-link fence. This is, Ernst believes, the first artificial hibernaculum for prairie rattlesnakes attempted in North America. Inside, I could see several burrows as well as a lower fence and partial canopy of chicken wire. Snakes sat in the open or moved slowly across the ground. One surprised us, rattling at our feet just across the fence. Ernst pointed to a fat female he is hoping will give birth in a few weeks. I asked how he built the hibernaculum.

"First, we dug down two metres, to get below the frost line, and built a chamber out of heavy plastic pipe, the kind they use for big waterlines. I insulated it and filled it back in. Then I connected it with a tunnel and built an outer chamber. I put a temperature probe in so we can monitor the temperature. The coldest it ever gets is 50C and the warmest it gets is about 18, even if there has been a month of 35-plus outside."

This simple structure placed in the right habitat means that a snake in trouble can now be moved just beyond the city's newest suburbs to a place not that far from its home range. The key is effective monitoring. After Ernst brings a new snake to the artificial den, he tags it by inserting a ricekernel-sized microchip into the tail portion of its body cavity. A relatively innocuous identification tool, like bird bands, the tags have nine-digit number-and-letter codes that can be read at arm's length with a wand. Over the course of the season, he collects several snakes, mostly from neighbouring subdivisions and country estates. Feeding on mouse carcasses donated by the Lethbridge research station and on ground squirrels trapped at the Lethbridge Country Club Golf Course, the snakes have all they need to survive and breed normally.

Until this year, Ernst has always held the snakes he captures and released them the following spring. Many returned to the artificial hibernaculum in the fall on their own, adopting the place as their new den. He has also kept back females that mated the previous year, hoping they would bear young. Four batches of neonates have been born at the site, including one large group that overwintered well and were released the next spring.

In its fourth year, the artificial den seems to be working. Snakes are breeding, bearing young and surviving the winter, and some rattlers released from the pen have returned to use it as their wintering site. Now the project's management plan has evolved to its second phase. Any new snakes captured are simply released at the den site, some outfitted with temporary radio-tracking transmitters to ensure that they don't wander back into trouble and also to collect data on how they use their new home.

People, however, continue to be the main threat to the snakes of Lethbridge, even those safe within the fences of the artificial den site. A week before my visit, two men from the Edmonton area removed a snake from the enclosure. A family from Lethbridge out for a walk in Cottonwood Park at the time caught the men carrying the snake in a bucket and insisted that they release it. After a few tense moments, the men let the rattler loose. The people who stood up for the snake reported the incident to local Fish and Wildlife officers.

Ernst tells stories like this with some pride, happy that education is producing results. There is no question that people in cities like Lethbridge and Medicine Hat are becoming more accepting and even proud of the rattlesnakes which share their river valleys. In Paradise Canyon, support for the rattlesnake-recovery project is high and roadkill rates are low these days, though Ernst is quick to point out that this may reflect a local thinning out of the species. As he knows too well, only the passing of the years will prove whether it is possible to maintain a healthy population of prairie rattlesnakes on the fringes of suburbia.

When Paradise Canyon was built, one of the early occupants was seen stopping his vehicle and backing up to run over a snake on the road. Since then the "Watch for Wildlife" sign has been replaced with a more pointed "Snakes are at risk Watch for snakes" posting. And now, according to Ernst, education is changing attitudes. "Last year, I got a call from someone saying, 'Hey, I just saw a rattlesnake on the road into the subdivision, and there was a big lineup of cars waiting for it to cross. People were getting out to get a better look.' "

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