Mist hangs over the woodland, and the air is damp and heavy with the musky-sweet scent of rain-soaked soil and decay – perfect conditions for seeking out snails. However, despite being celebrated in a Portland stone sculpture at the start of the trail, my target species – the cheese snail (Helicodonta obvoluta) – has a reputation for being elusive.
The nature reserve is located on the site of the old lime workings, where until the second world war chalk was quarried and burned in a series of lime kilns. During the war, the site was used by the Admiralty for enemy mine disposal, but at the end of the conflict, the site was abandoned. Left to nature, the landscape has slowly regenerated, developing into a habitat rich in chalk downland species such as the cheese snail, which favours a calcium-rich substratum.
The vegetation is lush in the deep, steep-sided quarry bowls, with hart’s tongue and male ferns licking up from the undergrowth, their fronds glistening with water droplets. But cheese snails aren’t attracted to verdant growth. They rely on dead wood and leaf litter for egg-laying, shelter, hibernation and food, consuming a varied diet of fungi, lichens and slime moulds.
On the high ground flanking the path, fallen trees have been left to rot, their bark furred with moss and sprouting oyster mushrooms and artist’s bracket fungi. I carefully roll over decomposing branches and crumbling trunks, sending woodlice and common centipedes scuttling for cover. Woodpeckers and nuthatches have jammed hazelnuts into crevices in the bark and I almost mistake the first cheese snail I encounter for part of their cache. Its shell is rufous-brown and just over a centimetre wide. The depressed spire gives it a flat-topped shape reminiscent of a wheel of cheese.
The British population is believed to be a postglacial relic, isolated in south-eastern England. Though widely distributed throughout Europe, the species is listed as near threatened on the International Union for Conservation of Nature red list, due to the diminution of forest cover and habitat fragmentation. So I’m delighted to peer through my hand lens and discover that this individual’s shell is covered with peach fuzz, indicating it’s probably a juvenile, as these fine hairs are typically absent in older specimens.
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