Wood Frog Mating Is A Wet, Competitive Orgy 

Wood Frog Mating Is A Competitive Watery Orgy

When wood frogs emerge from hibernation, a frantic competitive orgy happens. They meet up in frigid temporary pools left behind by melting snow, and over the course of just a few days, males grab nearly anything that moves in the hopes of winning a spot on a female's back.

Picture: Brian Gratwicke via Flickr

As soon as male wood frogs reach a pool, they pipe a quacking, chuckling call to let females know they're ready and waiting. But when females arrive, they don't exactly dive in. They're cautious when they enter the water, and for good reason. When males sense the ripples that a female makes in the water, they converge on her from all parts of the pool. If she isn't careful, she could wind up at the bottom of a mosh pile of pushing and wriggling males, each one trying to push the others aside and latch onto her back. As you can see in the video below, it's not pretty.

These mating balls can sometimes injure or drown females. So when female wood frogs feel waves in the water, they often swim away from the ripples. This behaviour, along with all the pushing and shoving, may ensure that the largest and fastest males in the pool father the most tadpoles.

For a male the whole goal of this competition is to get on a female's back and stay there. Hooking his arms under hers in a characteristic hold called amplexus, he may hang onto her for more than 24 hours, squirting out sperm as she lays an enormous mass of eggs. [Breven 1981; Howard and Kluge 1985; Hoebel and Kolodziej 2013]

Videos: Bryan Pfeiffer, Lindsey Swierk

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