How many snakes have you scanned today?
A project in Dinosaur Provincial Park has staff asking themselves that question. Implanted microchips are helping shed light on the habits of the prairie rattlesnake.
By Rob Hugill
At home in Dinosaur Provincial Park, located 50 kilometres northeast of Brooks, Alberta is the prairie rattlesnake. Here, amidst a unique combination of badlands, riparian and prairie landscapes is a rich diversity of flora and fauna generally considered to be at the northern limit of its range. Here, the prairie rattlesnake plays an integral role.
This venomous reptile Crotalus viridis viridis, mythical in proportion, from western lore, now finds itself "blue listed" as a species that may be at risk.
Over the past six years, park rangers have been tracking snake activity within the core area of the park (campground facilities, field station and service centre area) by recording snake sightings. With more than 60,000 visitors coming to the park every year, the potential for snake/human confrontations has become an increasing concern, both for public safety and the welfare of the prairie rattlesnake. As a World Heritage Site and premiere attraction within Alberta, the park is not only mandated to preserve but also to provide access to the public to enjoy and learn about its tremendous natural resources.
An obvious dilemma in affording visitors the opportunity to explore the park is that pressure is put on the natural resources. Until very recently, encountered rattlesnakes were routinely relocated to distant areas within the Natural Preserve, an area not open to the public. The simple act of distancing visitors and snakes avoided possible conflicts. The impact of relocation on the snakes was not observed or documented. The park's objectives today are to protect these unique reptiles by developing a better understanding of their distribution, movements and responses to relocation within the park. To achieve this though, it was clear to park management that a baseline of data on rattlesnake populations, movement patterns, habitat requirements and present resource management practices was required.
In 1996, park staff in a co-operative research venture, began working on a radio telemetry tracking program to monitor selected rattlesnakes. Staff hoped to locate unknown rattlesnake hibernacula (places where the snakes gather to hibernate over winter) and determine travel patterns within the park. Snakes captured from within the park that met the strict size requirements were surgically implanted with a two-centimetre round transmitter and 15-centimetre subcutaneous aerial. Andrew Didiuk from the Canadian Wildlife Service provided his technical and surgical skills to implant the transmitters in two snakes.
Careful measurements. Snakes captured within the park were required to meet strict size requirements to become part of the study. Photo by B. Bennett.
Upon recovery from the surgery the snakes were then released at the place of capture. Tracking then commenced. Movement was very erratic, making tracking a labor-intensive process. Capable assistance was recruited when Dave Scobie, project coordinator from Operation Grasslands Community, and his staff joined the project as partners.
Radio telemetry projects for prairie rattlesnakes have been conducted by Didiuk in the flat prairie terrain of the Suffield area. In 1996, Didiuk's preliminary results found that the rattlesnakes in the Suffield area were following a straight line from their hibernacula and returning in a similar straight line. In Dinosaur Provincial Park, radio telemetry observations provided a hibernaculum location within the Natural Preserve. Snake movements appear to be unique to the park population. It was established that the badlands terrain of the park is not conducive to straight line movement by the prairie rattlesnake.
Financial support for the first year of the project was provided by the Wildlife Management Enhancement Fund. Recognizing that with limited manpower and resources for the following seasons, a new methodology was implemented. With the partnership efforts of Ed Hofman, wildlife biologist, Prairie Region, a different approach to monitoring rattlesnake movement is now being employed. All rattlesnakes that are spotted and successfully captured receive a microchip implant (PIT tag) that is capable of providing an operating life exceeding 75 years. The telemetry procedure, on the other hand, required large snakes and the transmitter only lasted six to eight months. Using a syringe, a microchip with a bar code is implanted approximately 15 centimetres from the anal vent. The procedure is quick and places minimal stress on the snakes. At this time, the snake is also weighed, sexed, measured and the number of buttons on the rattle counted.
A Global Positioning System (GPS) location is taken at the capture and release site. All captured snakes in the future will be scanned and if the snake has been implanted the bar code will be recognized. The new GPS location will be compared to its past location and measurement data taken for comparison. During the 1997 season, 15 rattlesnakes were implanted for the study. Although the data will vary from that of the telemetry the microchip implants are already proving to be a successful method for rattlesnake monitoring and research.
Analysis of the data for the past two years has yielded some significant information that has been incorporated into resource management plans. We recognize that past relocation protocols were probably excessive. Further data collection and analysis will make estimates of population size and health possible.
In the future we hope to utilize both microchip implants and radio telemetry as funding allows. The implants will help to verify and enlarge baseline data for snake locations and growth. The implants however are not able to provide information on hibernacula locations. It is critical that these areas are identified and monitored to ensure the future survival of the snakes.
The prairie rattlesnake has adapted to the unique topography of the Alberta badlands. These adaptations have made monitoring and tracking them a challenging and rewarding project. The park is working to afford proper protection to the prairie rattlesnake through a greater understanding of these reptiles. Through continued education programs directed to park visitors it is further hoped to change the generally negative view of the prairie rattlesnake and other reptiles within the park.
In order to ensure that the ecological balance within the park prevails, efforts must focus on research so that sound resource management decisions can be made.
Rob Hugill is Chief Park Ranger at Dinosaur Provincial Park.