Monday, June 29, 2009

The legend of the pinging frogs

I want to tell you a story. It’s called “The Legend of the Pinging Frogs”. I wrote about them for The Independent two years ago, but the intervening summers were so bad, I hardly sat out in the garden at all. During the past week, however, the frogs have been at full ping so I thought I might revisit the tale.

I first heard the pinging shortly after we moved to this house, more than six years ago. I’d call it more of a high-pitched beep than a ping, and it sounded as if it was being emitted by something electronic. It was a warm evening in early summer and I was sitting outside. The noise seemed to be coming from somewhere near the junction box for the garden light, which was deep in a clump of bamboo.

I wasn’t used to having a garden light, and my first thought was that the bleeping indicated some sort of problem. I got up, looked at the light, and looked at the junction box. The noise stopped. I went back to my seat and glass of wine and sat down again. The noise resumed.

During the next few weeks (this was the very hot summer of 2003), the noise nearly drove me mad. It wasn’t so much the insistent bleeping (though that was fairly annoying), as not knowing its source. I wondered whether it might be a cricket or insect of some kind, or perhaps next door’s security light. There was no electronic equipment in the living room near the doors into the garden – such as a computer or a microwave – so I knew it wasn’t anything inside.

Eventually, the noise disappeared and I forgot all about it. Occasionally, I heard it again when, during the summer months, we had the windows open late in the evening.

So it was only during a chance conversation with my neighbour Jean that I had any clue as to what might be the cause. I’d been telling her about the frogs that live in a small pool in my garden and she asked me whether they were “pinging frogs”.

Apparently, so the local legend goes, the “pinging frogs” were introduced into a pond by the owners of a house in the next road about 20 years ago. Depending on whose version of the story you hear, the owners – or the frogs – were either Chinese or South American. Since then, the frogs have spread, apparently favouring paving slabs as a habitat. Neighbours are all agreed on one thing, however: the pinging is very annoying.

So, next question: what kind of creature was a “pinging frog”? The answer was the result of yet another chance conversation, this time with Anna Guthrie, of the Wildlife Trusts. Within hours, her colleague Brian Eversham, conservation director at the Wildlife Trusts for Beds, Cambs, Northants and Peterborough, came back with the verdict: the “pinging frog” was a midwife toad.

It all fitted. The midwife toad, Alytes obstetricans, was introduced to Britain about 100 years ago, to a nursery in Bedfordshire where it arrived in a consignment of plants from France. It can now be found in Bedfordshire, Northamptonshire, south Yorkshire, Hampshire, Devon, Surrey and … south-west London. It has a distinctive call, which many people apart from me have likened to an electronic beep, and it mates in May or June, which is when the calls are at a peak. That explains why at this time of year, they're in full throttle.

The midwife toad is a strange little creature. It gets its name from the fact that the male looks after the eggs, carrying them wrapped around his back legs until they’re ready to hatch, whereupon he dumps them into the nearest pond. I haven’t met anyone in our neighbourhood who’s actually seen a midwife toad, as they are tiny: about 5cms (two inches) long and their appearance, which is pretty similar to any other common or garden toad, keeps them well camouflaged.

It’s the male that does most of the calling, though the females anwer him back, and his call not only alerts them to his presence but also stimulates them hormonally, boosting their egg laying. Sounds a bit like a herpetological Tom Jones.

So “The Legend of the Pinging Frogs” is actually “The Case of the Midwife Toad”. Which is also, incidentally, the name of a book by Arthur Koestler about the German scientist Paul Kammerer, whose investigations into nature versus nurture involved experiments on amphibians and ended in tragedy after he was accused of falsifying the results. But that’s another story...

Here is a completely irrelevant picture of the first waterlily in my pond this year