Figure 1: The tiger snake, Notechis scutatus (Photo credit: Laurie Boyle, used under Creative Commons license CC BY-SA 4.0)
Australia is well known for its array of venomous creatures and the Tiger Snake is no exception. As urbanization increase, however, so does human-snake conflict. Is long distance translocation a viable way to keep residents safe while protecting this snake species?
WHAT IS THE TIGER SNAKE?
The tiger snake (Notechis scutatus) is a medium-sized venomous snake, growing up to 1.2 metres in length, named for the distinctive tiger-like vertical stripes along its body. Technically not a viper, these snakes are members of the Elapidae family, thus are more closely related to cobras than to rattlesnakes. Tiger snakes inhabit much of southern Australia and are particularly fond of wetlands and coastal areas where they hunt for their preferred prey, frogs, though they will also eat birds, mammals, and lizards. Globally, this species is classified as “least concern” by the IUCN, however, it is a protected species in Australia under the Wildlife Act (1975). Tiger snakes are a top predator in Australia’s ecosystems and are heavily reliant on habitat availability to support their diet, though this makes them vulnerable to habitat fragmentation. Occasionally, Melbourne’s tiger snakes will travel into residential areas in search of food and shelter, but due to their perceived threat to humans, those that are found are often captured and translocated to ‘safer’ natural areas.
A view of the Melbourne skyline, with the Yarra River flowing through its core. Melbourne is located on the southeastern coast of Australia, and is the nation’s second most populated city (Photo credit: Georgfotoart, used under Creative Commons license CC BY-SA 4.0).
ARE THERE TIGER SNAKES IN MELBOURNE?
The tiger snake is the most commonly encountered venomous snake in the Melbourne area. Westerfolds Park, in particular, is home to a local population of tiger snakes and is located in the Yara Valley Parklands, less than 20 kilometres away from Melbourne’s city-centre. In Westerfolds Park human-snake conflict is of particular concern as the park receives nearly 500,000 visitors annually, is located in a residential area, and is a site were licensed snake catchers often release captured Tiger snakes from nearby residential properties. The park itself is 123 hectares in size, and is bordered by the Yarra River to the north and west and by residential areas to the south and east. A six-month study was conducted in Westerfolds Park from spring 2002 to automn 2003 to investigate behavioural differences between translocated and resident tiger snakes (Butler et al. 2005a, b).
Figure 3: Map of Westerfolds Park, less than 20 km from Melbourne’s city-centre (Photo credit: Nick Carson, used under Creative Commons license CC BY-SA 4.0).
HOW DO TRANSLOCATED TIGER SNAKES BEHAVE?
The tiger snakes translocated to Westerfolds Park were obtained from licensed snake catchers who had caught the snakes on residential properties within 5 km of the park. The average tiger snake home range is under 4 ha, thus the snakes in this study were most likely removed from their natural home ranges (therefore these would be considered long-distance translocations). The study authors were interested in comparing the home range size and the total distance traveled between resident and translocated snakes. Fourteen snakes were implanted with radio-transmitters (six resident snakes, and eight translocated snakes) and were tracked 2 to 5 times per week during the study.
The translocated snakes had, on average, a home range six times larger than resident snakes (28.1 ha vs. 4.9 ha)! Also, translocated snakes were far more likely than resident snakes to leave the park boundaries and enter residential areas; one individual was captured and moved back to the park four times as it consistently returned to a specific residential property. Despite this, only 3 snakes died during the study (2 residents, and 1 translocated). The translocated snakes did not travel more frequently than the residents, but when they moved they covered significantly greater distances. By the end of the 6 month study, however, the translocated snakes appeared to have re-established new home ranges.
WERE TRANSLOCATIONS TO WESTERFOLDS PARK SUCCESSFUL?
This study supports other research demonstrating behavioural differences between translocated and resident snakes (see Urban Vipers 6: Dugites in Perth, Australia). Translocated tiger snakes traveled further and possessed larger home ranges than resident snakes in their new environment. Additionally, many of the translocated snakes chose to move back to residential areas, suggesting a preference for those habitat types, perhaps due to the presence of prey animals. The study authors speculated that translocating snakes outside of their home ranges into an urban nature reserve may actually increase conflict in that area, as some snakes will “spill over” into surrounding residential communities.
As the fast pace of urban sprawl continues, human-snake conflict will inevitably increase in Melbourne. Long-distance translocation remains a contentious management practice for mitigating human-snake conflict as it may simply shift a conflict scenario from one residential property to another. While translocation can be a beneficial tool to manage interactions with venomous snakes, translocation distance, proximity of the release site to residential areas, and species-specific responses must be understood to improve success for both people and snakes. While long-distance translocations do not appear to be the best solution for conflicts between tiger snakes and people in Melbourne, other options, such as short-distance translocations, may result in better outcomes for snakes (see Urban Vipers 8: Red Diamond Rattlesnakes in Loma Linda). Continued research into management strategies is needed in order to create a future where Melbourne residents can live harmoniously with their snake neighbours.
“Until the implication of translocation for both snakes and humans are fully understood, we recommend caution in the use of this management practice.” – Butler et al. 2005a
Authorship note: This blog post was originally drafted by Remo Boscarino-Gaetano, and revised and edited by Alexis Simeoni, Natasha Dobos and Jonathan Choquette.
REFERENCES
Butler, H., Malone, B. and Clemann, N. 2005a. Activity patterns and habitat preferences of translocated and resident tiger snakes (Notechis scutatus) in a suburban landscape. Wildlife Research. 32: 157-163.
Butler, H., Malone, B. and Clemann, N. 2005b. The effects of translocation on the spatial ecology of tiger snakes (Notechis scutatus) in a suburban landscape. Wildlife Research. 32: 165-171.
Cornelis, J., von Takach, B., Cooper, C., Vos, J., Bateman, P., and Lettoof, D. 2023. Quantifying the impacts of an invasive weed on habitat quality and prey availability for tiger snakes (Notechis scutatus) in urban wetlands. Wetlands Ecology and Management. 31: 715-732.
WPC appreciates funding support provided by the Ontario Ministry of Environment, Conservation and Parks’ Species at Risk Stewardship Program for WPC’s Ojibway Reptile Recovery Program.
