SAVANNAH, Ga. - As kingsnakes 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 kingsnakes, 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 kingsnakes and 2,012 copperheads. Fort Stewart was one of the study sites in Georgia, along with the Joseph W. Jones Ecological Research Center at Ichauway in the southwest corner of the state. The data indicates that declines in the kingsnake populations coincide with increases in the copperhead populations. Why that happens is open to interpretation.
"What may be happening when the kingsnakes 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.
Kingsnakes are "very catholic, indiscriminate predators," Stevenson said. They constrict their prey, dining 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.
The study didn't look at why kingsnakes 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 kingsnakes."
Kingsnakes, while in definite decline in some areas, are not listed as threatened or endangered.
The study's authors point out that if kingsnakes are regulating copperhead populations, the public is likely to find that a valuable service.
"Indeed, some individuals already relocate incidentally encountered kingsnakes to their property in hopes of reducing abundances of venomous snakes," the study states, noting the practice might not really work and relocating kingsnakes might increase the snakes' chances of dying.