‘What good are frogs?” It had all the spin of a googly. (This from cricket: a ball from a right-arm leg-spin bowler, out of the back of his hand; otherwise “a wrong’un”, bouncing the wrong way to catch you out at the wicket).
Delivered among friends to get the evening's craic going, the question had me swinging wildly for creatures that find frogs good to eat: otters, badgers, stoats, hedgehogs, pine martens, herons, kestrels, magpies. As for tadpoles, the list starts again, beginning with fish, diving beetles and the larvae of dragonflies. Large or small, Rana temporaria is one of nature's takeaways.
But this was not where the question was coming from. The spin was the subtext: what good are frogs for people (apart, of course, from the French)? For that I can now offer a few Googlings of my own. There’s a claim, for example, that some 10 per cent of Nobel prizes in physiology and medicine “have resulted from investigations that used frogs”. Remembering frog dissection from my school biology classes, this may seem rather sweeping.
On more convincing lines, perhaps – this from Google Scholar – the glands in the skin of the common frog have yielded antimicrobial peptides called temporins that have potential to fight the resistant infections in hospitals. Even in the totally utilitarian view of nature, the promise of new cures for human ills are a reason for keeping diversity: Ireland hopes to make a pharmaceutical fortune from new things discovered in the sea.
The evening's sortie into frogs was prompted by a recent national survey of Rana temporaria, including the ponds and ditches of Mayo. Had it (this with relish) involved an actual counting of heads? My explanation – worldwide decline of amphibians, just checking Ireland still has its frogs where they should be, and so on – did not impress my spin bowler: "Species have always come and gone."
They have, indeed, over millions of years. But, by the latest reckoning, Earth is losing species at some 1,000 times the planet’s “background” extinction rate. A great number of organisms, especially among the microscopic creatures of deep ocean, are still undescribed. Most new discoveries are concentrated into small areas and are more vulnerable to pressure from the human population, which has trebled in the past 50 years.
The value to people of natural ecosystems that provide clean air and water, food and material goods now has to be counted in cash, as politicians and bureaucrats can think only with figures. So how many species can we actually do without? None of them by some reckonings, as “everything is connected to everything else”.
Ecologists sort plants, animals and insects for this wider significance. Frogs, for example, are keystone and sentinel species. Their tadpoles take their stored energy and pass it up the food chain to everything that eats them. Frogs, eating slugs and midges, serve some human interests before themselves being eaten. Their health in our wetlands gives warning against pollution that could also wipe out all other aquatic life.
Keystone species are not always the obvious ones. Bumblebees are clearly one of them, for their pollination of crops and wild flowers. But the yellow, mound-building meadow ants, from new Irish studies, could be almost as important as earthworms in deciding how well the grass grows.
Such species are basic to the human food supply, and we must hope that their ecosystems survive the pressures of climate change. Many others will be lost, or need to move, as their habitats are transformed by rising temperatures, drought or flood. David Attenborough, speaking earlier this month at Westminster, urged a new approach to conservation, one that embraces the flow of new species from the south but also creates new wildlife corridors for the northward migration of the original, temperate settlers.
This, he suggested, needs more than national parks and wildlife reserves, and the use of every potential green space, including surburban gardens and the verges of roads. (You can watch his lecture at rspb.org.uk/forprofessionals/conference- for-nature). I wondered how he would talk to the Irish Farmers’ Association, currently calling on local authorities to control the ragwort now in vigorous yellow flower on wide road verges outside their fences.
Potentially toxic to many livestock (mainly horses) when wilted and saved among silage or hay, ragwort has long been a “noxious weed” theoretically banned by law. Now largely eliminated from better-tended pastures, it spreads freely by wind-borne seeds.
Spraying will kill many other wild plants for which green verges are a last refuge. Selective mowing at midheight, while a conceivable control on metre-tall ragwort and thistles, is managerially improbable. Neither is there much use mentioning, I’m sure, the pretty cinnabar moth and dozens of other insects for which ragwort is their chosen food plant.