Signs of Summer 9: More Snakes!

Carl Meyerhuber is a longtime friend and teaching colleague, and he is also a lifetime reptile lover. Carl told me last week that he had found an old Pennsylvania Fish and Boat Commission pamphlet that listed and described the five most common snakes of Pennsylvania (a copy of this pamphlet, by the way is available on line (http://fishandboat.com/anglerboater/2012ab/vol81num1_janfeb/08play03.pdf ). He asked me to name which snakes I thought would be on the list, and I only got three out of five!

Photo by Mike Pingleton (Wikimedia Commons)

The three that I knew were the black rat snake (called the “eastern rat snake” in the pamphlet), the eastern garter snake, and the northern water snake. These are three snakes that I have seen frequently and up close in a wide range of habitats throughout Western Pennsylvania. These are also snakes that I have written about in this blog and on the Virtual Nature Trail species pages. The two, “most common” snakes that I didn’t know are species that I have almost never seen in the wild: the eastern milk snake and the northern ring-necked snake.

Carl and I talked about the milk snake and were both quite surprised that it was on the “most common” list! I had only seen one milk snake here in Pennsylvania, and Carl had never seen any! “My” milk snake was disturbed out of a well mulched azalea bed right next to my house. We were pulling out some azalea bushes in order to clear the way for the construction of a wooden porch deck, and the snake, a brightly colored, red-black-yellow banded individual that was about 2 feet long, quickly moved out of its hideout in the mulch and headed down into my orchard and burrowed into a pile of leaves. I hadn’t seen that snake before that afternoon (even though it was living right next to my house!) and I haven’t seen it since! (My hope is, though, that it is living under the deck right now!).

So why hadn’t I seen that milk snake before, and, why hasn’t Carl, a great observer of snakes and turtles in his yard and along local hiking trails, ever seen one of these snakes? They are big snakes (two to five feet long!) and so brightly colored that they always stand out against grass or leaves. They live all across Southern Canada, and in all of the continental United States, Mexico, Central America, and northern South America! They are opportunistic feeders that eat everything from rodents to birds to frogs to other snakes, and they live in a wide range of habitats.

So why don’t we see these bright colored generalists everywhere? The simplest explanation is that milk snakes are nocturnal. They are active when we are, basically, not!

Now I just thought of a good question: why is a nocturnal snake so brightly colored? Those colors would be hardly observable in the dark, what evolutionary role could the milk snakes bright colors play?

My best answer is, “I don’t know.”

Maybe the colors help to camouflage it in its day-light hideouts? (unlikely). Maybe the colors startle potential predators that might come upon it during the day? (the more brightly colored snakes escape from the predators?) (possibly). There are a good number of possibilities and maybe’s here (and it’s speculation like this that makes science so much fun!!)

Photo by David Hoffman (Flickr)

Carl and I talked for a while about milk snakes but didn’t get to the northern ring-necked snake. It turns out, though, that the ring-neck snake is also nocturnal. They are smaller than milk snakes (only ten to fifteen inches long) and dark colored (except for their eponymous yellow ring around their necks), and they live quite quietly under logs, and rocks, and dead vegetation especially in wet forest habitats (although they can live in many types of forest and field ecosystems). Estimates of the numbers of ring-necked snakes in a prime habitat range from 28 to over 700 individuals per acre! That’s a lot of snakes! In many regions of the United States they are by far and away the most abundant snake species! They are found extensively over the northeastern half of the United States and southern Canada, but are very poorly known and seldom observed even by those of us who might be out there looking! Like the milk snake, they are a companion species in our ecosystem, but they are active out of phase with us in time!

So, when we cluster around our campfires (or lit decks or porches) we should remember that just outside the edges of the comforting glow of light are any number of species that are thriving, mostly invisibly (to us). Raccoons and possums are slipping by in the shadows, coyotes, are padding past undercover, and great snakes like the milk snake and the ring-necked snake are slithering past keeping rodent populations (and maybe even each other!) under control and within stable bounds.