Snakes in the garden, part 2: the black snakes

Black rat snake (Pantherophis obsoletus) coiled around an orchid in a large flower pot

Start with Part 1 of Snakes in the Garden.

The North Carolina piedmont is home to three large constrictors that are mostly black in color:  the eastern kingsnake (Lampropeltis getulus), black racer (Coluber constrictor), and black rat snake (Pantherophis obsoletus).  Although kingsnakes are found in our area, I have not been lucky enough to find one in my garden.  Racers and rat snakes, however, are common and–at four to six feet long–difficult to miss.

Black racers and black rat snakes are both colloquially referred to as “black snakes.”  The two species are roughly the same size and at first glance can be difficult to tell apart.  As a rule of thumb, if a black snake lifts its head to watch you and then slides rapidly away, it’s probably a racer.  If it freezes, perhaps coiling back in a defensive position, and then moves away slowly and methodically, it’s probably a rat snake.

Black Racer (Coluber constrictor)

A black racer periscoping out of a rosemary bush to keep an eye on me.

More than any other snake, black racers give an impression of alert intelligence. They actively prowl our flower beds, examining vole holes, flower pots, and other possible cover for prey.  They’re quite difficult to photograph, because they disappear so rapidly when they realize they have been spotted.

From time to time, I uncover clutches of racer eggs hidden in mulch piles or rotten stumps.  Usually they have already hatched, and each leathery eggshell has a small slit where the hatchling cut its way free with its egg tooth. A few years ago, I accidentally uncovered an intact clutch.  As it was now exposed to the elements and predators, I decided to collect the eggs and incubate them in an old fish tank.   The eggs hatched at the end of July, and the hatchlings were immediately ready to defend themselves by striking vigorously.  They also vibrated their tails, producing a buzzing sound that was surprisingly similar to a rattlesnake’s warning.

Racer hatchlings showing the juvenile pattern that will eventually darken to solid black. The brownish object is an eggshell stained by tannins from the mulch it was buried in.

After taking the hatchlings to school for “show and tell,” we released them in the garden, hoping that they would grow up to defend it against rodent pests.

Black rat snake (Pantherophis obsoletus)

Like racers, juvenile rat snakes are patterned with saddle-like blotches, and they darken with age. However, many adults retain traces of this juvenile pattern and never become solid black.

Rat snakes are excellent climbers and frequently raid nests for eggs and nestlings. Our neighbors who keep hens sometimes lose eggs, despite their best attempts at snake-proofing the chicken coop.  To protect our bluebird nest boxes, we have mounted metal baffles on the posts.

Rat snakes can climb straight up the trunks of large trees by gripping the furrows in the bark.

Despite their predilection for raiding bird nests, I like having rat snakes around the garden.  They help to control rodent populations, and it is always exciting to see such a large and exotic animal going about its business,apparently undisturbed by our presence.

A large rat snake visiting our deck.  The cats were not amused.