Friday, September 28, 2007

You Knew We’d Have to Talk About Snakes, Sooner or Later

Checking out some road kill one morning while out on my dawn bike ride, I saw what looked like a very large (formerly alive) snake. It didn’t have rattles, but I wasn’t sure what kind it was. After doing some research, I determined that it was a bull snake. Here is what I learned.

There are 46 species of snakes in New Mexico, but only 8 of them are poisonous. These include 7 species of rattlesnakes and a type of coral snake. The bull snake, so named because some think it makes a bull-like snort when threatened, is a non-venomous snake that relies on mimicry to defend itself. It might coil up and make a hissing sound while shaking its tail. Of course, this is likely to remind its enemy of a rattlesnake. It can even somewhat flatten its head to resemble that of a rattler, although (unlike the rattlesnake) the bull snake’s head and neck are actually of the same width. If this behavior doesn’t frighten off the perceived enemy, the bull snake might lunge toward it. Personally, I would have been long gone, but readers of this blog already know that it doesn’t take much to send me packing (see The Big, Big Spider and the Brave Red Shoes post).

The bull snake (Pituophis melanoleucus sayi) is a subspecies of pine-gopher snake (Pituophis catenifer). It is found in the U.S. west, the south, and the southeast in deserts, forests, coastal dunes, and grasslands or agricultural areas. It is often associated with prairie dog towns. We have a lot of prairie dogs right around where we live, although their habitat is rapidly being dug up and turned into housing lots, so it's not surprising to find bull snakes close by.

It is one of the largest snake species in the U.S., ranging from three to eight feet, but usually averaging around five feet in length. It is brown, yellow-brown, or cream colored, with black and brown markings.

It feeds on mice, rabbits, ground squirrels, prairie dogs, lizards, ground-nesting birds and their eggs, and even other snakes. Because it helps control rodents, it is really the farmer’s friend, and some farmers will allow a bull snake to live under a porch or in a barn. It constricts, or squeezes, its prey and then eats it whole, usually head first. In turn, it is preyed upon by coyotes, kit foxes, red-tailed hawks, and eagles.

Bull snakes are diurnal, which means that they are active during the day, although they may also be about at night during hot weather. They hunt in the early morning, late afternoon, and early evening. They hibernate in the winter, denning* with other bull snakes and sometimes with rattlers, racers, and even garter snakes.

They mate from March through April, and the clutch of 5 to 19 leathery eggs is laid in loose soil during July or August. Hatchlings emerge in early autumn, and must find their own way in the world, as there is no parental involvement.

In captivity, bull snakes have been known to live up to 22 years. However, because they are comparatively slow moving, in the wild they are often killed when crossing roads or basking on roadways. This road danger, together with ongoing habitat destruction, considerably shortens their average life expectancy.


*The idea of snakes denning in a great mass is an intriguing one to me and has been so ever since I read the children’s book, A Gathering of Garter Snakes, by Bianca Lavies. I highly recommend this book, which is about the famous Narcisse Snake Dens in Manitoba ( You can borrow Lavies’ book at your library, of course!


For more information about bull snakes, visit these web sites.

Desert U.S.A.:

Enchanted Learning--For a drawing of the bull snake constricting and suffocating (and eating) its prey:

Natural Source; An educator’s guide to South Dakota’s natural resources.

Texas Parks and Wildlife:

For a very interesting and somewhat disturbing (well, I found the part about trapping snakes using a glue board and then freeing them using vegetable oil disturbing, but you might not) article on snakes in New Mexico, read New Mexico Snakes — recognizing the poisonous ones and controlling them around homes, by James E. Knight, at
Thanks go to my New Hampshire herpetologist friends, Tanya and Andy, for technical advice for this post.


Towanda said...

NO! NO! NO! Not a snake post!!!!! Even with a picture!!!!

clairz said...

Well, you know they're here and I was hoping that having more knowledge about them might help. But NO, I had to find out that bull snakes are active during the day. That's a big help!!!!

Towanda said...

I'm not really afaid of snakes, we routinely killed rattlesnakes when we lived in Texas. And I have heard in Santa Fe at 7000 feet elevation we might not have many. I guess I worry most about my dogs encountering snakes...they have never seen one before. Do you watch your dogs very closely to make sure they don't encounter a snake and decide it is something to play with?

clairz said...

Good grief, we just have a little old fenced yard that is all nice, short lawn. I'm hoping there aren't any snakes out there. When we lived in Las Cruces we used to take our dog out on the desert all the time. I'm sure plenty of snakes saw us, but we didn't see them. Just a matter of luck.

I know poisonous snakes are a concern for dog owners. I've heard about snake aversion training for dogs. It just sounds kind of creepy, for both the dog and the snake.

Lin said...

Clairz - GREAT research, write-up and links! I am also concerned and have been warned by locals about dogs running into rattlers.

The dozer operator was not fond of snakes at all. In the course of work, he had once dozed through a winter den with swarms of rattlers in it and not inclined to socialize with snakes thereafter.

My apologies for messing up your direct comment. It was bound to happen; I finally hit 'reject' instead of 'publish' and lost several comments. I was able to submit it myself with post data material but if you like, do send it again so that it retains all its links.

It was just announced that my evening generator time is coming to an end (unless I wish to stay up and go out to shut it down myself later ... NOT) so I will be back for a longer visit soon!