Rare poisonous snakes need protection too

Patrick Weatherhead has been inserting tiny radio transmitters under the skin of black rat snakes living in the Rideau Lakes area north of Kingston, Ontario. Michel Villeneuve has been tagging massasauga rattlesnakes on Beausoleil Island in Lake Huron's Georgian Bay.

Both measures are intended to aid the survival of increasingly rare species.

But many ''cottagers'' in this summer-resort area of ''thirty thousand islands'' might disagree with those conservation activities. Mr. Villeneuve, a warden in Georgian Bay Islands National Park, reckons that, whenever these shy reptiles are spotted in areas outside the park, most people try to kill them.

''Perhaps 90 percent of the time, the snake is destroyed,'' he guesses. That saddens him. It partially explains why the massasauga is evidently becoming rarer outside the national park. ''People are naturally scared of snakes, especially poisonous ones,'' the warden said.

Nevertheless, Canadian wildlife authorities are moving to protect these creatures. The federal-provincial Committee on the Status of Endangered Wildlife in Canada has assigned studies on the status of various species of snakes, especially those endangered to some degree by man. Mr. Villeneuve's work is part of that program.

Dr. Weatherhead's research, on the other hand, is funded by the World Wildlife Fund of Canada. Actually he's an ornithologist. He became interested in the black rat snake because it raids bird nests for the fledglings, as well as swallowing rodents. He has found that the scientific information available about snakes is much more scarce and less sophisticated than that concerning birds.

''We are doing natural history on snakes,'' he said. ''We need to understand the basic biology of the creatures.''

Earlier this year, he implanted radio transmitters deep under the skin (to prevent ejection during shedding) of six of the tree-climbing black rat snakes. Apparently it was the first time this has been done in Canada and perhaps anywhere.

Since then, with the aid of three students, he has tracked the serpents daily. None has moved more than 11/2 miles from where it was caught. Nor are the five- to six-foot-long snakes all that active, though they do move as much as one-third of a mile in a day.

The snakes shed their skin three times each summer, and they stay put for two weeks while doing so. When a snake sheds, it also sheds the scale over its eyes. So its vision is probably clouded, and it may feel staying hidden is safer.

The black rat snake, Canada's largest snake, used to be widespread in southern Ontario. Now its habitat is apparently limited to the Rideau Lakes area. Dr. Weatherhead suspects their decline is largely due to people clubbing them. But he hopes to find out this winter where they ''overwinter'' to see if these sites are being disturbed, thereby endangering them.

Serpents this far north hibernate in the winter. Some, like garter snakes, gather together by the hundreds or even thousands in hibernaculums, or dens. But no one knows if black rat snakes - or, for that matter, massasauga rattlesnakes - come together in large numbers. At this time in the fall, Dr. Weatherhead reports, his six individual snakes have slowed down with the cooler weather, staying in such places as wood piles or under cottages. He suspects - but won't find out for a few weeks - that they do not get together in a group to hibernate. Such scattering may improve the chance of the species surviving, Dr. Weatherhead figures.

Meanwhile, Mr. Villeneuve is carrying out a five-year-old study of the fairly rare massasauga rattlers in the national park near here. In the past three years , he personally has run across only one massasauga on Beausoleil Island. However , many thousands of campers and others visit the island each year. Thus the park wardens are called frequently by someone spotting these protected rattlers - on average about 50 times a year.

The wardens come quickly; pick the rattlers up with a snake hook, on which the vipers tend to balance themselves; and pop them into a garbage can with a lid that fastens tight. Some are carefully tagged through their rattles, which are dead tissue. Thus the procedure is painless. All the snakes are then let free elsewhere on the island, with the colored tags showing the date and place.

The idea is to track their movements and learn more about these rattlers. Unfortunately, few of these tagged snakes are subsequently caught. New information has thus been sparse. However, one was caught on a another island more than a mile from Beausoleil. ''All snakes are good swimmers,'' said Mr. Villeneuve.

This past summer was somewhat cold, and there were fewer visitors to the national park. Mr. Villeneuve figures these factors may explain why he and his colleagues caught only 23 rattlers by late August.

One of the 23 snakes caught this year seemed especially chubby. When Mr. Villeneuve let it go, he saw it give birth to three eight-inch young ones before it slithered out of sight. Few humans have seen a massasauga give birth. In 15 minutes, those young rattlers were ready for business, mouths open, fangs showing, and trying to rattle their still-wet rattles. They, too, quickly slid away, adding slightly to the island's estimated population of 400 rattlers.

The park officials are trying to educate the public that the two- or three-foot-long rattlers should be spared - that they are not aggressive or even terribly dangerous. The massasauga rattler, Mr. Villeneuve explained, has only short fangs, which would have difficulty penetrating even wool socks.

Actually, the rattlers are useful creatures. Their main diet is mice. The snakes have vertical pupils, like cats, that enable them to see relatively well in the dark. Moreover, rattlers are ''pit vipers'' with two heat-sensing devices between their eyes and noses. These help them pinpoint rodents or other small mammals accurately. Their venom finishes off victims quickly before they are swallowed whole.

Mr. Villeneuve's ambition is to find the winter hibernating place for the cold-blooded rattlers. He suspects that many of them may gather in one hibernaculum. He hopes to obtain funding for implanting tiny radio transmitters in some rattlers. By finding the hibernaculum, if one exists, national park officials could plan further camping developments on the island without further endangering the island's rattlers by possibly destroying a hibernation den. The island is one of the few scattered places in Ontario where the massasauga survives.

One rare massasauga trait is that it gives birth to only some seven to nine young each year, compared to 30 or 40 for this region's more plentiful water snakes.

Francis R. Cook, curator of the herpetology section of the Museum of Natural Science in Ottawa says he thinks the rattler is doing ''amazingly well,'' considering the large influx of cottagers into their habitats. He expects some groups of the snake can be protected in national or provincial parks. But he isn't sure they can be protected elsewhere, considering they are poisonous. ''Where is the cutoff point?'' he asks. ''That is the kind of decision that just gets made.''

The timber rattlesnake has not been seen in Ontario since 1941 and may be gone already. Ontario also has on its list of endangered snake species the blue racer and the Lake Erie watersnake. Irene Bowman, an official with the Ontario Fish and Wildlife Department, says an educational program is attempting to tell the public of the useful role snakes play in nature, eating rodents and insects. But basically, she thinks, the snakes should be saved ''for their own sakes.'