Country diary: tiny toads star in their own fast-forward evolution movie

Country diary: tiny toads star in their own fast-forward evolution movie

A mild southerly breeze, overcast, rain spitting into the leathery green of the dog-days – toad weather. The old railway line that runs down Wenlock Edge through Northway Wood cuts across the steep scarp slope. On an evening like this it is a quiet place. It hasn’t seen a train since the early sixties and has been used for taking out timber and walking since then, but as an open ride through woods it is a vibrant passageway for wildlife traffic.

Small white butterflies flickering through seemingly random flight patterns along the edges of the track may be the very localised wood whites, Leptidea sinapis, expanding their range in Shropshire and characteristic of old railway lines and woodland rides. If they are, they are second-brood females looking for tall trefoils and vetch to lay eggs on, and it would be great to see a thriving population of them here. Southern hawker dragonflies zip through 90 degree turns without slowing down; buzzards float in the space between tree canopies; wasps hide under hogweed umbels; robins and wrens call from late-flowering honeysuckle; grey squirrels leap into hazel branches.

While the eye is distracted by the action above, it is at ground level that something extraordinary happens. What first appear to be hesitant, scuttling spiders turn out to be toadlets. See one, see 10, then be aware of hundreds of tiny toads, less than half an inch long, the colour of the track’s wet ballast.

Toads, Bufo bufo, have fixed eyes and learn to distinguish between edible prey and dangerous predators. In the fading light it would be hard for them to see much but they can detect low-frequency vibration, moving forward in short bursts and “listening”, busily seeking shelter in the enchanter’s nightshade, bramble and grasses from danger above.

There are no large ponds nearby, so these toadlets have emerged from ditches and puddles along the track and, in this moment, have ventured on to land together in a kind of fast-forward evolution movie. This cohort, with amphibian intelligence, disperses into the surrounding vegetation with nothing much to protect them but a faith in their own toxicity and a wonderfully collective appetite for life.

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