What a shock it was to see behaviour I had seen in frogs round 1959 described within the information media a few weeks in the past. And what a delight after I seemed up the unique paper that the identical behaviour had first been recorded by Ronald Henry Maxwell Savage (1900-1985) (see my earlier articles right here and right here) in 1934.
The current paper which attracted media consideration reiterated Savage’s observations on feminine Widespread Frogs, Rana temporaria. In to order to flee amplexus, which might generally, or typically, contain a couple of male within the female-grabbing frenzy of what the authors time period ‘explosive’ breeders, the feminine makes use of a numbers of ways. Grunting (regarded as ‘I’ve already laid my eggs so you might be losing your time’ sign is one such tactic. Others are rolling sideways and taking part in useless for sufficiently lengthy for the males to lose curiosity. Totally different ways had been employed by feminine frogs of various dimension. Bigger ones primarily grunted and rolled; smaller ones did the identical however had been extra prone to seem useless.
Amplexus of a single feminine with a lot of males is thought to be a harmful exercise for the feminine which might result in drowning. So eager are the males that even goldfish in the identical pond might not escape the clutches of a male frog.
These ways of mate avoidance could be interpreted in two methods. First, they permit a feminine to pick a mate, maybe on the idea of who can kick away their rivals. Second, the feminine whereas having arrived on the breeding pond is probably not physiologically able to ovulate and lay eggs, and having males hanging on for longer than needed could also be a harmful encumbrance. In different phrases, on a selected event, are females ridding themselves of specific males or all males.
I noticed and heard all of the ways described in Widespread Frogs I used to be preserving round 1959. For some cause I can not now keep in mind I had them in a big container in my grandfather’s greenhouse. I recall there was just one feminine with about 4 males. After all of the mating ball exercise, issues settled down with only one male in amplexus. The feminine didn’t lay her eggs till a couple of week later which at all times led me to suppose that there was some physiological course of occurring resulting in ovulation. In contrast in our backyard pond (till it was ruined by native vandals) I’ve seen females be a part of males and lay their eggs throughout the first evening of amplexus.
Dittrich C, Rödel M-O. 2023. Drop useless! Feminine mate avoidance in an explosively breeding frog . Royal Society Open Science 10, 230742 DOI: 10.1098/rsos.230742
Savage RM. 1934. The breeding behaviour of the widespread frog, Rana temporaria temporaria Linn., and of the widespread toad, Bufo bufo bufo Linn. Proceedings of the Zoological Society of London 104, 55-70.