Environmental Almanac | A love of wildlife — even snakes

Environmental Almanac | A love of wildlife — even snakes

Thanks to a friend who's more observant than me, a few years back I discovered a new species of reptile in my own backyard. It was a plains garter snake, known by scientists as Thamnophis radix.

I should clarify by saying I mean the plains garter snake was "new" to me, not new to science or the wider world.

I should also add that it's not the case I had never seen a plains garter snake before or even picked one up — just that I had never recognized one as something other than a common garter snake, which is the kind of garter snake I was familiar with where I grew up in surburban Cincinnati, Ohio.

Common garter snakes belong to the same genus as plains garters, Thamnophis, but they are recognized by scientists as a separate species, named sirtalis.

Most people wouldn't notice the difference between a plains garter snake and a common garter snake at first glance, but with a decent photograph, the field marks that distinguish them are easy enough to pick out.

The plains garter usually has wider black bars on the margins of its labial scales than the common garter, and its mid-back stripe tends toward orange-yellow, whereas the one on the common garter lacks the orange tinge. The most certain difference between them, though, is the position of the light-colored lateral stripe on the side. On the common garter, it occurs on the second and third row of scales (counting up from the wide belly scales), and on the plains garter it occurs on the third and fourth.

Understanding that I had not properly identified the snakes in my backyard at home prompted me to look back at photos I've taken this year of the garter snakes that inhabit one of my other backyards, the landscaping along the Boneyard Creek on the University of Illinois campus.

Sure enough, they're plains garter snakes, too.

To most of the world, I suppose distinguishing between plains and common garter snakes is about as important as distinguishing between different sorts of bats or spiders — as long as they can be avoided, who cares?

As for the other animals with which they share a habitat, there's not much difference between plains and common garters either. Like all other snakes, both are carnivores and eat just about any creature they can catch and swallow. Depending on their size and where they live, this may include earthworms, slugs and other invertebrates, as well as small amphibians, birds or fish. Both also serve as a source of food for the same variety of predators — birds of prey, midsize mammals and other snakes.

My interest in knowing the difference between various species of garter snakes is rooted partly in my habit of (obsession with?) "collecting" animals and plants by photographing them; being able to identify more species means being able to collect more.

Of course this raises the question, "Why collect plants and animals in the first place?" The un-fancy answer to that is "because." To me, there's nothing more interesting. (The existence of zoos and museums and nature centers and private collections affirms I'm in reasonably good company here.)

The fancier way to characterize this impulse would be to call it an expression of "biophilia," defined by the great scientist and naturalist E.O. Wilson in his 1984 book of that name as "the innate tendency to focus on life and lifelike processes." For Wilson and others who have pursued the implications of the "biophilia hypothesis," our "love of life" (biophilia translated literally) is key to our survival as a species and healthy development as individuals.

Does your love of life extend to snakes? When I told her about the topic of this column, my spouse suggested I also write about creating snake habitats in your yard. Maybe I'll come back to that in the future, but for now, let me just emphasize there's no reason to fear (or harm) any of the snakes commonly found in central Illinois. They pose no threat to people and often do us good by helping to control rodent populations.

A few more garter snake facts:

During winter, garter snakes hibernate in underground cavities in groups. But, they tolerate cold better than most other reptiles, and may even come out to bask in the sun on warm days in winter.

While garter snakes pose no threat to people, they do produce tiny amounts of a mild venom that can help subdue prey — just enough to slow down a frog, for example.

Common garter snakes tend to be feisty when handled, but plains garter snakes often don't mind being picked up by people.

Rob Kanter is a clinical associate professor with the University of Illinois School of Earth, Society and Environment. You can reach him via email at rkanter@illinois.edu.

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