Please Brake for Snakes! - Road Mortality of Snakes

As mentioned in the previous blog post, vehicle traffic on busy roads are risky for animals trying to cross to get to the other side for breeding or hunting purpose. Due to the misconceived malign nature of snakes, these species are suffering from intentional killings on the roads (Langley et al. 1989). A similar roadkill experiment was performed by Mark Rober (a former NASA engineer who designs simple experiments to test interesting questions) in recent years, in which he showed that drivers cared less about tarantulas and snakes over turtles, that turtles usually received greater conservation efforts and the majority of people were more fond of turtles (but sadly some people are still running over them!). In the video clip, he addressed the fact that the control of his experiment, a leaf, was never hit by any vehicle suggested that these hits were probably intentional. This result was consistent with the study of snake and turtle road mortality (MacKinnon et al. 2005).

Video: https://www.youtube.com/watch?v=k-Fp7flAWMA

The effects of roadkill on reptile populations have long been recognized by scientists (e.g. MacKinnon et al. 2005; Shine et al. 2004; Row et al. 2007). In May, many snake species migrate from their hibernation sites to breeding and mating grounds (Shine et al. 2004). Due to the high density of road developments in Ontario, most species would encounter highways and gravel pavement during their movements (MacKinnon et al. 2005). However, MacKinnon et al. (2005) showed that the peak mortality of snakes happened in August. The results implied that traffic density would be the determining factor of road mortality because the traffic was highest during August in the study site, Georgian Bay (MacKinnon et al. 2005). On the other hand, some species actively seek out sun-warmed road surface for thermoregulation (e.g. Ashley and Robinson 1996). Row et al. (2007) suggested that road mortality alone was detrimental enough to cause a local decline of large bodied snakes populations, such as it was for the Frontenac Arch and Carolinian gray ratsnake populations. Intraspecific variation between male and female snakes was also observed in gray ratsnakes, indicating that females suffered more from road mortality (Row et al. 2007)
 

Some Stats!

→ Gray ratsnakes had a road mortality rate of 0.026 deaths per crossing in Ontario (Row et al. 2007).

→ Ashley and Robinson (1997) recorded a mortality rate of 0.34 reptiles/km/day in Lake Erie, Ontario.

→ The highway mortality rate was 22.5 snakes/km/year in Southern Arizone (Rosen and Lowe 1994).

→ In the Central Andes of Colombia, roadkill rate of snakes was as high as 78.8 individuals/km/year (Quintero-Ángel et al. 2012).

Please brake for snakes!

So, what can you do to help reduce road mortality of snakes and wildlife in general? If it is safe to do so, simply just brake and avoid running over the animals. Pull over and check whether the animal is alive. Report to Wildlife Services in your region and seek for help!

Brake for snakes is a non-profit making organization that raises awareness and educates the public about wildlife conservation, especially for snakes. They urge motorists to avoid roadkills that are done either accidentally or purposely.

Let’s see what PEI residents have done for their duckies!

Video: https://www.youtube.com/watch?v=dQkPQ66blLk

References:

Ashley, E. P., and J. T. Robinson. (1996). Road mortality of amphibians, reptiles and other wildlife on the Long Point Causeway, Lake Erie, Ontario. Canadian Field-Naturalist 110(3): 403-412.

MacKinnon, C. A., L. A. Moore., and R. J. Brooks. (2005). Why did the reptile cross the road? Landscape factors associated with road mortality of snakes and turtles in the South Eastern Georgian Bay area. In Proceedings of the Parks Research Forum of Ontario (PRFO) and Carolinian Canada Coalition (CCC) Annual General Meeting (pp. 153-166).

Quintero-Ángel, A., D. Osorio-Dominguez., F. Vargas-Salinas., and C. A. Saavedra-Rodriguez. Roadkill rate of snakes in a disturbed landscape of Central Andes of Colombia. Herpetology Notes 5: 99-105

Rosen, P. C., and C. H. Lowe. (1994). Highway mortality of snakes in the Sonoran desert of Southern Arizona. Biological Conservation 68: 143-148.

Row, J. R., G. Blouin-Demers., P. J. Weatherhead. (2007). Demographic effects of road mortality in black ratsnakes (Elaphe obsoleta). Biological Conservation 137: 117-124.

Shepard, D. B., A. R. Kuhns, M. J. Dreslik., and C. A. Philips. (2008). Roads as barriers to animal movement in fragmented landscapes. Animal Conservation 11: 288-296.

Shine, R., M. Lemaster., M. Wall., T. Langkilde., and R. Mason. (2004). Why did the snake cross the road? Effects of roads on movement and location of mates by Garter Snakes (Thamnophis sirtalis parietalis). Ecology and Society 9(1): 9.