Wood Ants in the Winter

Ants are the most numerous creatures on the planet and there are many millions of them living around the woods of East Dartmoor, but why is the species of red wood ant (Formica rufa) such an important part of our woodland ecosystem? These wood ants that build the familiar ‘thatched’ nests are a familiar sight during the summer and, occasionally, it can be quite difficult to find a place to stand where these centimetre centurions aren’t crawling all over your laces.

Red wood ants actively foraging in the summer

Though they are classified on the IUCN red list as ‘near threatened’, red wood ant nests are common around these woods and they can reach quite a size. The hundreds of thousands of ants in each colony construct their nest from the twigs, leaves, needles and other bits and pieces of plant material scattered around the woodland floor. From the outside, they may look like an uncoordinated heap, but these nests are intricate works of precision engineering. They are solar powered and rainproof with a complex network of passageways, ventilation shafts and chambers both above and below ground, but it’s all hidden away beneath the huge dome of plant material they call home.

Masses of wood ants responding to the warmer days of spring

In spring, lines of crawling ants can be seen with leaves and twigs, many times their body weight, carrying them back to the nest. The growing nest can seethe with life; masses of shiny black and red bodies absorbing the heat of the sun and, when in such vast numbers, you can even hear the intense activity of millions of tiny legs going dutifully about their tasks.

Red Wood Ant in defensive posture
Red wood ant in defensive posture

In the heat of the summer the wood ants protect their nest, avidly defending their home turf. They have powerful pincers, but they also have a longer-range weapon. They can send a jet of acid spray skywards from their abdomen. If you get too close you may sense the ‘chip-shop vinegar’ smell of formic acid, sprayed to keep imposters (that’s you and me) away. They often feed in the tree tops, taking honeydew from aphids, but will also catch other invertebrates. It’s not unusual to see a caterpillar, legs in the air, being marched back to the safety of the ants’ nest. The ants play their part in the web of woodland life, maintaining the balance of nature. Preying on other insects and, in turn, providing a meal for the woodpeckers; their long, coiled tongue can reach the ant super-highways under cracks in the bark.

Other species find ways to survive winter in the woods

Inevitably, the seasons change and taking a wintry walk in the woods is a good time to find wildlife clues. Badger prints in snow and deer ‘slots’ in wet mud all give an indication of what’s around the woods but, as I recently watched a light flurry of snow settle on a collapsed ant nest, I thought, I haven’t seen any of these 6-legged friends for months, not since the end of the autumn. This is where another essential role of the ants comes into play. The period of inactivity allows the huge heap of nesting material to decompose; passing nutrients back into the woodland soil as the ‘thatch’ sinks down in a slowly decaying mass. But where are the wood ants? How do they get through the cold winter when food is scarce? The majority don’t survive but, deep down in that old nest, are the underground chambers where the queen ants and the last remaining workers wait for warmer weather.

A dusting of snow on a ‘thatched’ wood ant nest

In spring, when the sun’s rays start to heat the remains of last years’ nest, the first ants will resurface, starting the whole cycle again, keeping the colony alive.

This blog was first published on the Fingle Woods blog and was written by Matt Parkins

Find out more about UK Wood Ants at www.woodants.org.uk

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