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NICK BAKER'S DARTMOOR WINTER

Nick Baker is a professional ‘amateur naturalist’ who loves all things with a pulse (and quite a few things without!). He works as a TV broadcaster, author, photographer and wildlife tour guide.

Queen Hornet

It’s relatively well known what a Dormouse is doing around about now: it’s tallying up its annual seven months of shut-eye – hence its old colloquial name ‘the seven sleeper’. The Hedgehog is pretty much doing the same under your garden shed, or is balled up in a pile of brash or leaves somewhere at the foot of a hedge. Bats are hung up like furry, dewy baubles or stuffed into crevices in walls, caves or rot holes in trees, depending on species.

But what about the others, that under-appreciated majority? Where do all the insects go? They don’t have the muscle to head south with the birds, but on a spring day – and sometimes through the winter months – they seem to spontaneously appear.

It’s probably not that surprising to learn that many species of invertebrate sit out this inclement season in various robust stages of their life cycle: for many this would be in an insignificant egg jammed into a bark crevice or, as is the case for grasshoppers and crickets, deep in the soil.

Have a search around your outhouses or porches and you may find the chrysalis of the Large White butterfly, self-sewn to a firm surface. This strategy is a popular choice among many butterflies and moths. The shiny mahogany sarcophagi – the pupae of several common moth species – are often discovered while turning soil in the garden over the winter season.
More unusual are species such as the Silver Washed Fritillary. That grand butterfly of high summer lays its eggs on the bark of trees near the caterpillars’ food plant: violets. In late summer these hatched and immediately sought refuge in a crack or crevice in the bark – without a square meal inside them. Next year’s Silver Washed Fritillaries sit out the worst the Moor can throw at them as tiny, empty scraps of caterpillars. As I walk the wintry woods I imagine just how many of these barely living miniatures I’ve passed, jammed deep in some recess. How and why they do this? Just another mystery of the Moor.

Similarly, the Marsh Fritillary overwinters as a caterpillar. As its name suggests it likes damp places, but risks being flooded out. With the help of its siblings it spins a waterproof silken tent that can survive being submerged: a caterpillar life-support capsule.

How do these creatures tolerate the cold? This permeating menace to our warm-blooded lives is well understood, but if you are cold-blooded and outside it’s a different story. Sub-zero temperatures will freeze water, and the formation of expanding ice crystals in your cells would be fatal.

Many species simply burrow and wriggle into those insulated places. Dig into the earth; flip a stone or dip a net into a pond or river and you will find plenty of life. Have a forage for yourself if you don’t believe me. Life in water is a constant; here on Dartmoor it always seems cold! But the fact that this changes little means many insects carry on regardless of the season. Water is a poor conductor of heat and so is slow to warm up and cool down. Dartmoor’s rivers, with their continuous oxygenated kinetic torrents, are perfect places to avoid the winter. Have a rummage in the gravel or lift some stones in the shallows and you will find various nymphs scurrying from your sight. These are juvenile stages of many familiar insects, from Mayfly to Caddis, Dragonfly to Midge: next year’s summer sensations in preparation.

Others, such as some of our most familiar garden species – Brimstone, Small Tortoiseshell, Peacock butterflies and various other insects (such as aphids, ladybirds and Hornets) – can tolerate sub-zero temperatures too. Loft spaces, unheated sheds and greenhouses are good places for a seasonal sit out. They are at a constant cool temperature, and the insects turn on some pretty interesting physiology to increase their chances: they get rid of excess water before hibernating, then lower the freezing point of their blood by having a kind of built-in anti-freeze in the form of polyhydric alcohols. Others are able to control the formation of damaging ice crystals, allowing them to form in ‘safe’ places so that when they defrost their bodies don’t turn to a mushy pulp (along with their futures).

Just the name used to describe them – the ‘lower plants’ – would put most people off. The Mosses and Lichens are extremely successful plants (I use the word ‘plant’ here loosely as technically a Lichen is a fungus that plays host to an alga within its tissues – a form of symbiosis – and although some of these alga species can be found outside of a host fungus the converse doesn’t apply, and a Lichen simply wouldn’t be without the plants inside its cells!). The fact that they are small, slow-growing and not particularly extrovert counts against them. Give these encrusting and cushioning life forms a second glimpse over the winter months and you might be pleasantly surprised.

Dartmoor – being what it is and where it is – gets a regular drenching. This abundance of the elixir of life gives the place its character: the Moor wouldn’t be a moor without the eight common species of Sphagnum mosses that form the blanket bogs that in turn act as a sponge, keeping its major rivers running all year around. The high rainfall provides the perfect conditions for these Mosses and Lichens to flourish. Winter is a great time to appreciate this diversity, partly because the larger plants have retreated into roots, tubers and rhizomes, and the leaves have dropped. Our eyes, hungry for some signs of life, pick up on the ever-present but less showy forms, but also in the damp atmosphere these plants are at their most lush: rehydrated and full of vigour.

Let your imagination run wild as you hunt for Lichens with such poetic names as Crottle, Rock Tripe, Map Lichen, Devil’s Matchsticks, String of Sausages and Knicker Elastic! There are simply hundreds of different kinds, but if you want to get to know them a little better it wouldn’t be a bad idea to get a field guide to some of the commoner ones (the Field Studies Council produces some useful fold-out guides for about £2).

The National Park states that you may find up to 60 species of lichen on a Dartmoor tor – now that sounds like a challenge to me!