Dear Readers, I wouldn’t want you to think that I’m obsessed with the sex life of frogs, but clearly I am. A few weeks ago, I reported on how male frogs have a tendency to attempt to mate with whatever object comes within range, and it appears that this behaviour goes back a very long way, to when the very first frogs appeared out of the primordial ooze and started ribbiting away. Well, this week the plot thickens, as it appears that female frogs have come up with some interesting behaviours to try to dampen the ardour of these lotharios, who can sometimes drown a female with their overzealous advances.
Scientist Carolin Dittrich, of the Natural History Museum in Berlin, observed the behaviour of two female frogs, one larger and one smaller, when placed in a miniature pond with a male for an hour. When grabbed by a male, 83% did a sharp rotation, which might have been a way of testing the male’s strength or an avoidance tactic, or possibly both. 48% made a specific call known as a ‘release call’, which basically means ‘get your hands off me you pest”. Usually this call is made by a male when grabbed by another male, but the females have learned to mimic it.
And 33% of the females demonstrated something which scientists call ‘tonic immobility’, and you and I might call ‘playing dead’.
In total, 46% of the females managed to escape from the male, which is reassuring, at least to me: I’ve sometimes seen my pond full to brimming with eager male frogs, and have watched as a newly-arrived female frog sits on a rock surveying the scene, as if deciding whether or not to take the plunge. Of course, I know that I’m anthropomorphising but it’s difficult to avoid making a comparison with when I was 15 and was just about to enter the school disco, though fortunately I didn’t end up drowned or with several thousand eggs to worry about. Incidentally, it was the smaller, younger female frogs who were most able to wriggle out of a male frog’s slippery embrace, so maybe this is a good thing, giving them a bit longer to mature and get up to a proper breeding weight. It’s clear that female frogs don’t just go along with the male’s advances, but make some choices themselves.
I will definitely be paying more attention to ‘my’ frogs next year, to see what they get up to. What a privilege it is to be able to observe the behaviour of these animals in my own back garden! I hope I never forget how lucky I am.
You can read the whole paper here.