A dugite (Pseudonaja affinis) basking (Photo credit: itsnature.org/ground/reptiles-land/dugite/)

The Species

Pseudonaja affinis, commonly known as the dugite, is a slender venomous snake found in Western Australia that can grow up to 2 metres long. Dugites are technically not vipers as they are members of the family of venomous snakes called elapidae, which includes cobras, coral snakes, and black mambas. The dugite has a semi-glossy appearance and ranges in colour from brown, to olive brown, to brownish grey, with irregular black spots on its scales. These snakes are very active during the day, foraging for prey such as mice, rats, and lizards, while escaping detection from predators such as birds. Dugites inhabit coastal dunes, heathlands, shrublands, and woodlands, and are also known to frequent the urban habitats of Perth, a city in Western Australia. Dugites have been observed using golf courses, other human-modified grassy areas, and areas around sheds and buildings, often seeking refuge under artificial cover.

The Locale

The City of Perth, Western Australia (Photo credit: www.travellens.co/best-things-to-do-in-perth-australia/), and the distribution of the dugite (Pseudonaja affinis) in Australia (Photo credit: reptilesofaustralia.com/snakes/elapids/paffinis.htm#.YrHf3xZE0WM).

Perth is a large city located in southern Western Australia, with a population of over 2 million residents (Figure 2). Although highly urbanized, the city of Perth is split by the large Swan River and contains many large parks and urban bushlands. This gives 54% of Perth access to greenspace within 400 m of their dwelling, ranking it fourth in Australia for greenspace access! But Perthians aren’t the only ones to benefit: the dugite is well established in Perth’s urban wilderness and is in fact the most common snake found in the city. As a result, urban dugites are subjected to threats including road mortality and human-snake conflict. People will sometimes kill dugites out of fear of snakebite, or move (aka translocate) them away from conflict areas to nearby urban bush lands. These translocations, however, aren’t necessarily a long-term solution due to the potential for harming the snakes, or facilitating repeat encounters between dugites and humans.

The Methods

Translocation is the intentional release of an animal into a different site from where it was originally captured. This technique is sometimes used to manage wildlife in urban areas when individuals are found too close to people. Although the humans involved may feel relieved once a venomous snake is translocated, what happens to the snake? In a study by Wolfe et al. (2018), researchers compared the movements of resident dugites to those of translocated dugites to determine the impact of translocation on individual snakes. A total of 10 healthy snakes were captured during the active season (Sep. – Dec.) in the Perth metropolitan area and used in the study. Most of the snakes were “problem” snakes that were found on private properties and were to be translocated. The 10 snakes were divided into two translocation groups: 1) four that were to be translocated a long distance from their capture sites (moved at least 3km away), and 2) six that were to be left alone or translocated only a short distance from their capture site (moved 0 to 200m). Each dugite had a telemetry package attached externally to its tail, consisting of a radio-telemetry transmitter and a GPS data-logger. All snakes were released into suitable bush land habitat and checked on once a week for up to 2 months.

The results of this study showed that snakes translocated a long distance (LDT) had significantly higher activity ranges compared to snakes translocated short distances (SDT). The two groups did not, however, vary in distance travelled. Unfortunately, long-distance translocation appeared to detrimentally affect snake survival; 100% of LDT snakes died during the study, compared to only 50% in SDT snakes. All deaths were the result of predation events or road mortality. Overall, these results indicate that removing urban dugites from familiar habitats and translocating them far away can negatively affect movement and survival. Presumably, translocated snakes increased their movements to find suitable or familiar resources and habitat, and therefore exposed themselves to a higher than normal risk of predation and road mortality.

Final Thoughts

This study on the dugite showed that long-distance translocations were not a viable long-term solution to managing human-snake conflict. Although the snakes were removed from conflict sites, and presumably saved from being killed outright by frightened residents, in the end they all died anyways. If people and venomous snakes are to coexist, the more effective way to ensure positive conservation outcomes is to move these animals only short distances from where they were found. What qualifies as a “short” distance will of course depend on the species and the typical size of its home range. Snakes seem to become intimately familiar with the area they consider “home”, and we might say they become lost if moved too far away by people. For the dugites of Perth Australia, there truly is no place like home.

“With increased understanding, we too might appreciate venomous snakes as living symbols of wilderness; perhaps we can even afford them a place in modern landscapes.”

Harry Greene, 1997

Professor of ecology and evolutionary biology, Cornell University

Jonathan Choquette

Lead Biologist – Ojibway Prairie Reptile Recovery Program

Jonathan manages the recovery program for the Ojibway population of the massasauga rattlesnake in Southern Ontario. Jonathan’s research interests lie in the field of urban herpetology, having studied both biology and landscape architecture at the University of Guelph. Jonathan has authored or co-authored numerous reports and publications about the conservation of Canadian reptiles and amphibians in urban environments.

Jonathan Choquette