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Wild Things

The weird and wonderful in the natural world

Sarah Zielinski

Wild Things

Wild Things

How a snake named Hannibal led to a discovery about cobra cannibalism

cape cobra cannibalizing another cobra

Scientists working in the Kalahari Desert spotted this cape cobra, which they later named Hannibal, eating a smaller cape cobra. The find set off a search for how common the practice of cobra cannibalism really is.

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Studying the diet of snakes isn’t easy. The animals are elusive, and they don’t feed all that often. It probably doesn’t help that some of them can be deadly to humans. So perhaps it’s not much of a surprise that scientists hadn’t realized how common one category of snack is for southern African cobras: each other. But once researchers started looking, they realized that cannibalism among cobras happens far more frequently than anyone had thought.

Bryan Maritz, a herpetologist at the University of the Western Cape in Bellville, South Africa, hadn’t set out to study cobra cannibalism. He and his colleagues were conducting a study in the Kalahari Desert of two species of snakes: cape cobras and boomslang.

“The snakes raid these huge colonial social weaver nests and eat all the chicks and eggs,” Maritz says. The researchers want to better understand how the two species use the birds and their nests, and they were looking for snakes that they could implant with radio transmitters.

One day this past January, though, while searching for snakes, the researchers got a radio call from a tour guide who told them where to find a pair of large yellow snakes engaged in a fight. Thinking those yellow snakes might be cape cobras, the team raced to the site. They didn’t find a snake fight but did find one large cape cobra swallowing a smaller one.

“Instead of capturing two potential study animals, we found one well-fed study animal, now known as NN011, or more casually, Hannibal,” Maritz and his colleagues write in a paper published October 1 in Ecology.

This wasn’t the first documented sighting of a cannibalistic cobra, but scientists didn’t think such behavior was common. “The total number of observations of cobras eating in the wild isn’t a big number, and the observations of cannibalism in the wild are even rarer, so I think it’s easy to dismiss as a one-off thing,” Maritz says.

But Maritz had previous inklings that this practice might not be so rare. Before starting the cape cobra-boomslang study, he’d had students dissect museum specimens, and they found a surprising number of cape cobras that had eaten other cape cobras. The discovery of Hannibal, though, persuaded him that he needed to investigate just how common the practice was.

Maritz and his colleagues went looking for reports of cobra diets in research papers, newsletters and museum bulletins, and also solicited stories on Facebook. There are some 30 species of cobras in Africa and Asia, but the team restricted their analysis to six species, including the cape cobra, in southern Africa.

Snake-eating, they found, was common among five of the six species studied, accounting for 13 to 43 percent of the cobras’ diets. Conspecifics, snakes of the same species, represented about 4 percent of all prey items in the study, the researchers found. And because all cobra species share similar diets, the scientists think that cannibalism might be a characteristic shared by even more cobra species.

In all the cannibalism events that the researchers witnessed themselves, both the eater and the eaten were males, leading them to suspect that this behavior may be a male-only trait. More research will be needed to determine if that’s true. But if it is, Maritz says, “I could see it playing a role in competition for resources or mates. What better way to get ahead in life [than to] eat the guy who is taking your food and mating with females that you might want to mate with?”

Animals,, Ecology,, Oceans

A gentoo penguin’s dinner knows how to fight back

By Sarah Zielinski 2:12pm, September 4, 2018
Cameras attached to gentoo penguins off the Falkland Islands revealed that, despite the birds’ small size, their lobster krill prey can sometimes win in a fight.
Ecology,, Animals,, Conservation

Madagascar’s predators are probably vulnerable to toxic toads

By Sarah Zielinski 9:00am, June 19, 2018
The Asian common toad, an invasive species in Madagascar, produces a toxin in its skin that’s probably toxic to most of the island’s predators.

How a deep-sea geology trip led researchers to a doomed octopus nursery

By Sarah Zielinski 10:00am, May 15, 2018
A healthy population of cephalopods could be hiding nearby, though, a new study contends.

How a social lifestyle helped drive a river otter species to near extinction

By Sarah Zielinski 10:00am, May 1, 2018
A reconstruction of 20th-century hunting practices reveals why one species of Amazon river otters nearly went extinct while another persisted.

Pollinators are usually safe from a Venus flytrap

By Sarah Zielinski 7:00am, February 6, 2018
A first-ever look at what pollinates the carnivorous Venus flytrap finds little overlap between pollinators and prey.

Tiny trackers reveal the secret lives of young sea turtles

By Sarah Zielinski 9:00am, December 22, 2017
Young loggerhead turtles can end up in very different places in the Atlantic depending on when they hatch.

Coconut crabs are a bird’s worst nightmare

By Sarah Zielinski 7:00am, November 15, 2017
A biologist witnesses a coconut crab taking out a blue-footed booby and documents the balance of the animals in an Indian Ocean archipelago.

Alligators eat sharks — and a whole lot more

By Sarah Zielinski 9:00am, November 3, 2017
Alligators aren’t just freshwater creatures. They swim to salty waters and back, munching on plenty of foods along the way.
Animals,, Plants,, Ecology

Invasive earthworms may be taking a toll on sugar maples

By Sarah Zielinski 3:00pm, August 30, 2017
Sugar maple trees in the Upper Great Lakes region are more likely to have dying branches when there are signs of an earthworm invasion, a new study finds.

These spiders crossed an ocean to get to Australia

By Sarah Zielinski 9:00am, August 15, 2017
The nearest relatives of an Australian trapdoor spider live in Africa. They crossed the Indian Ocean to get to Australia, a new study suggests.
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