Mark Hendricks, Contributor Ω
The colour of a garter snake impacts how it survives in its environment, a wildlife biologist told the audience at a Jan. 31 environmental science seminar – and humans are changing that environment.
Humans engineer the area around us to best suit our needs. In the Okanagan we turn semi-arid landscapes into green vineyards. While the destruction of animal habitats is often a subject of discussion, less often is the ability of those animals to survive afterward.
“How an animal looks in its environment very much has implications,” said Leigh Anne Isaac as she points to a picture of a rattlesnake and a vineyard. “Habitats are being converted and so the habitat in which a rattlesnake is used to being in looks much different now.”
Isaac, who received her PhD in biology from the University of Victoria, was the guest lecturer for the third seminar in the environmental science seminar series put on by TRU. Isaac spoke to a crowd of approximately 40 about her research into the impact of color variance on a species.
Isaac’s research was inspired by a single question — why do garter snakes vary in colour? To answer this question, she set out to capture garter snakes that have two distinct colourations, light skinned and dark skinned. She would then measure differences in traits and behaviour.
“Seems straightforward but it isn’t, I guarantee you,” Isaac said.
Isaac’s work examined three areas: protection from predators, differences in behaviour and thermal differences.
The ability of a prey to avoid detection due to camouflage, of which colour is a primary factor, is known as crypsis. Isaac examined the crypsis of garter snakes by capturing them as they were basking and taking samples from the immediately surrounding area.
Isaac took these samples and measured the type of light that bounced back to obtain a measurement. The findings determined that for the area the snakes came from there was no difference in the crypsis between the two colourations.
Although crypsis was the same, the behaviour between the two colourations varied significantly. The light skinned snakes were quicker to flee when they were detected; however, the dark skinned snakes were significantly faster once moving.
The light skinned snakes also tend to be found further away from the nearest hiding point than their dark skinned counterparts.
The dark-skinned snakes had a longer life expectancy, as the lighter-skinned snakes were more vulnerable to predators; however, the lighter-skinned snakes had larger litter sizes
Temperature plays a large role in animals such as snakes and colour was found to play a strong role in temperature. Isaac found that the darker skinned snakes had higher average body temperatures.
Snakes are temperature sensitive and at higher body temperatures they are faster, have increased metabolic processes and enhanced digestion. This gives the darker skinned snakes a comparative advantage.
Isaac hopes her research will have more than merely academic impact. She hopes her research will have relevance to conservation efforts as we better understand the impact of changing an animal’s environment on its continued survival.
The environmental science seminar series is open to everyone and take place on Thursdays in room S203 in the science building. A full listing of dates along with abstracts of the presentations can be found on TRU’s website at https://www.tru.ca/science/programs/msces/mscseminar.html.