Wednesday, July 13, 2016

Eastern (Black) Ratsnakes

     The Eastern Ratsnake (Pantherophis alleghaniensis) is our longest and one of our most commonly seen snakes. Formerly called the Black Ratsnake (Elaphe obsoleta), both it's common and scientific names have been changed and formalized. But many people still refer to it as a Black Rat Snake or simply Black Snake. It is the longest snake in the region, the only one that regularly grows to over 6' in length. The world record is one that measured 101 inches from its snout to its vent. The Virginia record is a 67.3 inch one. Its large size along with ability and tendency to climb trees makes this snakes among the most visible in our area.
     Although the large size of Eastern Ratsnakes may make them seem intimidating, they are harmless to people. They will only bite if threatened or handled, and then only about half the time anyways. They prefer to slither away quickly, sometimes musking the perceived threat with a foul smelling liquid if handled. Eastern Ratsnakes will sometime curl up is an S-shape, hissing, vibrating their tail tips, and striking in an attempt to intimidate the potential predator into leaving it alone. The teeth are relatively small for such a large snake, leaving little pin pricks marks and not really causing any great harm. 
     This is a beneficial creature to have around. As the name suggests, they are superb at controlling rodents, being able to get into their burrows and tackling even large rats, killing their prey by constriction. They are however also opportunists, feeding on whatever is available and small enough for them to eat, including birds, eggs, salamanders, shrews, chipmunks, and sometimes larger prey. Because they are such good climbers, they sometimes get themselves in trouble with people who put up bird boxes that haven't been protected sufficiently, eating the occupants. 

Eastern (Black) Ratsnakes are excellent climbers and are often seen basking in trees.

     But overall, they are great allies and find plenty of rodents in urban areas to satisfy their appetites. They can really gorge themselves when food is plentiful. I once was feeding a large 6'+ ratsnake in a nature center I worked at. I was curious as to how many mice it could eat at one sitting. After 23 mice, I had nothing left to feed it, and it was still looking for more. 

     But ratsnakes can also go long times between meals. They can go months without eating if need be, their cold blooded metabolism being very efficient at not burning up energy reserves. This makes them arguably better at rodent control than other predators such as foxes, owls, hawks, and cats, who not only can't get into the rodent burrows, but also cannot go such long times with out eating, having to either move away or die. Not so with ratsnakes. When the rodents do return, they can resume eating with no real harm to the snakes.
     Luckily many people realize the benefits of having ratsnakes around. Sometimes they're referred to as the "Farmer's Friend" and purposely released into barns and out buildings. Their shiny black coloration, with a bit of white on their chin/neck and partial checkerboard pattern on their bellies helps to distinguish them from some of the other black snakes around. 
     But the young are sometimes confused with other snakes because they differ so much in coloration. They have a blotched pattern along their backs that turns all black as they age. Some people confuse them for other snakes such as copperheads or rattlesnakes (especially since these snakes, like many others, will shake their tails in the leaves and thus sometimes sound like a rattle). One of the best identification features for juvenile ratsnakes is a dark line that crosses the eyes to the mouth, almost like a unibrow. 

A juvenile Eastern (Black) Ratsnake, note the line connecting the eyes and blotched pattern.

     That the young sometimes put on a good show by pretending to be big and bad to scare away dangers sometimes backfires when they encounter people. This use to be a good defense against a predator that wasn't sure if it was dangerous. But now of course this can cause people to be frightened and often ends up with them killing the juvenile snakes. 

     Here's a short video from the Capital Naturalist YouTube Channel that shows you one such display: 

     Eastern Ratsnakes take at least 4 years to reach maturity and breeding age. They lay their eggs (from 5-44 of them depending on the size of the snake) in late June or July around here. They often seek a rotting log or compost pile, the site helping to keep the eggs warm. If the site is a good one, they may use it year after year. The eggs hatch 60-75 days later, with the parents showing no parental care other than finding a good place to hide the eggs and the young are capable of catching their own prey at birth. If nothing eats them, they can live up to 22 years and 11 months, the record so far in captivity. 

     Eastern Ratsnakes overwinter in a dormant state referred to as brumation. Brumation sites (hibernacula) are often used year after year, with some sites containing several snakes. Occasionally they will share the hibernaculum site with other snake species, including venomous ones such as copperheads and rattlesnakes. This has led to the mistaken belief that they can mate with venomous snakes and thus produce the patterned young. This of course is completely false.
     I always am thrilled when I find an Eastern Ratsnake, often still calling it a Black Rat Snake in my excitement. I always try and tell folks about how beneficial they are, try to allay people's fears. I hope that these great and adaptable snakes can live in harmony with us well into the future. This will benefit people, but I also want our younger generations to be thrilled to find a really big snake, like I always am, and be able to talk about them to their kids in the future.

No comments:

Post a Comment