Often, accurately identifying similar creatures can be difficult.
Here in Arkansas, there are a lot of snakes. (Have you have seen any of my other posts?) Many can look very similar, which can often lead to some confusion. This post is an attempt to help educate people about a few of the more beneficial, non-venomous species in North America. Thankfully, any indigenous snake that happens to be long and black will be non-venomous. The pit vipers like the Copperhead, Water Moccasin, and the Rattlesnakes are mostly stouter and are not solid black, so they can be easier to distinguish from the snakes that I am about to share with you.
RACER
BLACK RAT SNAKE
These are two fairly common species here in Arkansas, and they both also inhabited certain areas back in Wisconsin, so they have quite a range across the United States. As I said earlier, both of these snakes are non-venomous. They can also both grow several feet long and are great in helping to keep down the rodent population. Here is a short video of my explaining some of the differences.
HOW TO TELL THE DIFFERENCE
One of the first distinguishing characteristics is the head shape. The Racer of the left has a more slender head shape, where the width of the head is much more in line with the width of the body. The Black Rat Snake on the right has a body that narrows more at the neck and jaws that flare out farther than the width of the rest of the head, creating more of an "arrow" shape.
If you look at the scales on both of these species, they will look rather similar. Snake scales are snake scales, right? Well, there are differences. Let's have a closer look.
If you look at the scales on the Black Rat Snake on top, you'll notice that there are lines running down the center of the scales. Scales with these ridges running down the center of the center of them are called keeled scales. They differ from the smooth type of scales, as found on the Racer. These keeled scales also make the snake more rough to the touch.
The juveniles of these species are a whole different story, but at the adult age, you'll see still see some distinct differences from the side view. For one, some of the pattern can still be seen on the upper body of the Black Rat Snake. By this age, the Racers have mostly a uniform upper body color. Let's flip them over for a closer look at the bellies.
Here you can see another obvious difference. The Racer on the bottom will usually have a white or creme colored underbelly, which will be uniform for the majority of the length of it. Sometimes a more yellow coloration near the throat will be present, but the belly is mostly one solid color.
On the Black Rat Snake, however, there is a big difference with the underbelly color. From my observations, the underside usually starts out white under the throat, eventually transitions into a sporadic white with black spots coloration, then to black with sporadic red spots, and finally becomes a sleek, solid black color before the tail. This photo does not do this transition justice, so please refer to the video above for more on this matter.
CONCLUSION
The two longer, darker North American snakes overlap in their habitats and distribution. Both play important roles in the ecosystem and fill specific niches, and both are beneficial. Neither is venomous, and they usually will only bite in defense, which often happens when they are captured by humans.
Despite the similarities, there are some obvious differences as well. Hopefully this post had provided you with some information that will be helpful if you ever need to tell the two species apart.