It was nighttime on Kooragang Island, north of Sydney, Australia, when loud voices began to be heard. John Gould, an ecologist at Newcastle University who is conducting postdoctoral research on the island’s declining frog population, rushed toward the mysterious sounds. There, at a lake he had been surveying, he witnessed a scene reminiscent of a scene from an amphibious thriller like “Hannibal Lecter”…
Gould saw a large female frog grab a smaller frog by its hind leg and drag it into a hole to devour. “The male frog was trying very hard to prevent this from happening,” says Dr. Gould.
It was the first recorded act of adult cannibalism in this endemic Australian frog species (Ranoidea aurea) and gave Dr Gould the trigger to learn more about the subject. He concluded that when a female frog of this species, with its distinctive green-gold hue, is not satisfied with a male’s song, she may opt to make a meal of him.
The phenomenon
Females “are almost the greatest predators of males,” Dr. Gould said, because their ears are perfectly attuned to the call of their would-be mate. Cannibalism is well-known in amphibians. But it’s usually the younger frogs, toads or salamanders that end up as dinner. Tadpoles of several species eat smaller tadpoles, for example, to get ahead in life. In some cases, this happens regularly between siblings. In others, adults sometimes cannibalize eggs or larvae. Researchers recently discovered that some parents may also eat their young when faced with less-than-ideal water conditions.
A New York Times article states that cannibalism between adults is extremely rare, and the literature records only a few specific cases where the cannibal was a female larger than the male she attacked. Dr. Gould believes that a female who hears a male’s call decides whether she is satisfied enough to mate with him or whether he is completely indifferent as a mate but very interesting as a meal. This means that males take a huge risk when trying to attract mates. In essence, they are literally offering themselves and their lives for love.
But as you can see, attempts at cannibalism by female frogs can be a problem, as some males may fight back or the female may bite off and swallow a larger piece of the male than she can chew, causing her to choke. Cannibalism can also be a source of disease transmission between frog populations.
Males may fight back, for example, or females may choke by biting off more than they can chew. Cannibalism can also spread disease to infected populations.
For the record, the male frog that starred in the scene Gould saw managed to pull his leg out of the female’s hands and escape. Of course, if this guy doesn’t change the way he calls the females, we don’t know if he’ll be able to escape the next attacks from the females he’ll receive.
Naftemporiki.gr