Breeding season is dangerous for males Frog
Scientists on Kooragang Island in New South Wales, Australia, have observed adult female mountain and golden-spotted frogs for the first time.Litoria aurea ) preys on males during breeding season, the team detailed their findings in a study published June 12 in the journal Nature. Ecology and evolution
The researchers first observed this behavior when they heard a high-pitched call during an investigation.
“We hear them occasionally in the wild, but it’s usually frogs that are being preyed upon,” said the study’s lead author. John Gould
Following the screams, Gould realised they were coming from a male whose thigh had been almost completely swallowed by the female, who was then dragging him into a hole by the pond.
“The male frog was really trying to stop this from happening, so he was holding on to things around him, like sticks in the ground, to stop himself being pulled under,” Gould said.
The male was eventually able to escape. This observation led Gould and his team to compare their field observations over three consecutive breeding nights with other studies that have reported cases of sexual cannibalism.
Scientists have discovered a female green frog (like the one pictured right) biting the hind leg of a male of the same species. (Images by John Gould and Chad T. Beranek)
cannibalism Well documented in amphibians
Amphibians
Many species of frogs are sexually dimorphic, with adult females often being significantly larger than males.
“It’s very likely that females are using males not only as mates but also as prey,” Gould said.
The researchers speculated that this cannibalism may act as a process of natural selection.
During breeding season, females may discriminate between potential mates and prey depending on the quality of their calls: larger males with lower calls are deemed better breeding partners, while smaller, inferior males may be left as food.
But Gould suggests that even superior females may not be able to escape predation: Instead, males may choose to eat the female after she has bred and laid all her eggs, similar to female praying mantises, who decapitate and eat the female during or after mating.
“It’s dangerous for the male frogs, who are croaking so hard to find a mate but then have to take the added risk of being used as prey,” Gould said.
Scientists aren’t yet sure what influences this cannibalistic behavior — sexual cannibalism happens so quickly that it’s rarely observed — but that may not mean it’s rare, Gould said.
Gould noted that it’s relatively rare to observe male frogs mounting female frogs and fertilizing their eggs in the field, even though scientists know it’s necessary for reproduction.
More research is needed to determine how common this cannibalism is and what impact it is having on local green and golden frog populations, the team said.
