As king snakes decline in localized areas of the Southeast, the abundance of one of their common meals — the venomous copperhead — seems to be increasing.
Researchers collected ongoing snake survey data to look for changes in population sizes of the two species in the Southeast, publishing their findings in the journal Herpetologica.
Both snakes are native across most of Georgia. The nonvenomous king snakes, which grow to more than 5 feet long, are so named because they have a natural immunity to pit-viper venom, and so are able to prey on other snakes. They eat copperheads, a heavy-bodied venomous snake that can grow to a little more than 3 feet long.
From 377 traps deployed in an array of habitats, the authors recorded captures of 299 king snakes and 2,012 copperheads. The data indicate declines in the king snake populations coincide with increases in the copperhead populations. Why that happens is open to interpretation.
“What may be happening when the king snakes decline or are not present is it releases copperheads that are there from that predator pressure,” said Dirk Stevenson, a study author and assistant conservation scientist at the Orianne Society, a Georgia-based nonprofit dedicated to snake conservation.
King snakes are “very catholic, indiscriminate predators,” Stevenson said. They constrict their prey, chowing down on small mammals, lizards, birds and frogs. They’re even known to follow nesting freshwater and terrestrial turtles and devour a clutch of freshly laid eggs. Other snakes are on the menu, too.
“Where they occur with copperheads, they really do like scarfing them down,” said Stevenson, who noted they eat them headfirst so they “go down smoother.”
The study didn’t look at why king snakes are declining. Previous studies have suggested habitat loss, road mortality, pollution, toxin buildup in their tissues, fire ants and overcollection for the pet trade could all play a role.
“Over time a lot of pine habitat has become shadier and oakier due to successional changes due to fire suppression,” Stevenson said. “That change is going in the direction of favoring copperheads over king snakes.”
John Jensen, senior wildlife biologist with the Georgia Department of Natural Resources, said habitat loss doesn’t seem to be an issue because king snakes are declining in areas where habitat remains fairly intact and are stable other places where habitat has been disturbed.
“It’s a real big mystery,” Jensen said. “... A lot of people suspect that disease may be at play, but we don’t have any proof of that.”
Jensen didn’t have any data on snake populations in Northeast Georgia but noted copperheads are plentiful and anecdotal information shows king snakes declining in some parts of Georgia. He said copperheads are not necessarily increasing, though.
The study’s authors point out that if king snakes are regulating copperhead populations, the public is likely to find that a valuable service.
“Indeed, some individuals already relocate incidentally encountered king snakes to their property in hopes of reducing abundances of venomous snakes,” the study states, noting the practice might not really work and relocating king snakes might increase their chances of dying.
Removing shelters such as log or rock piles along with food sources may help residents keep snakes away, but Jensen said copperheads don’t need a large habitat, so the effort may not be worth it. He instead advised being aware of surroundings and carrying a flashlight at night.
In any case, Northeast Georgia residents likely have another month before they have to worry about snakes. Jensen said they will wait until it is reliably warm to come out, which may happen in April.