Dear Readers, I already knew that there were Treecreepers in Coldfall Wood. Last year, I spotted a tiny bird with a curved bill high up in an oak tree, scraping its head back and forth through the bark, but it was only there for a second before it flew away. This bird was the first Treecreeper that I’d ever seen in my fifty-five years on earth, yet this is not a rare species – there are estimated to be over 200,000 territories in the UK. They are well camouflaged, small and unobtrusive, but, once spotted, they can be very relaxed around quiet humans.

I saw this bird on Good Friday, the same day that I spotted the Song Thrush. I was walking back through the damp forest, feeling very pleased with myself, when there was a blur of wings and I realised that a Treecreeper was perched on a tree less than five metres away. What busy birds they are! This one flew to the base of the trunk and started to work his was up, methodically exploring the bark with that delicate half-moon beak for grubs and beetles and spiders. Once he got to the canopy he flew away. I congratulated myself on getting a couple of photos so that I could share him with you, and was admiring my handiwork on the screen at the back of the camera when he suddenly appeared again, on another tree which was even closer. This time, I got some film of him, though I apologise in advance (as usual) for the wobbliness. I do hope that you aren’t prone to motion sickness.

You might wonder why I am so sure that this bird is a male. Well, I’m not certain, but a Finnish study found that male Treecreepers tend to use the lower part of the trunk to feed (as this one was), whilst females use the higher areas. I imagine that this means that a pair don’t waste time covering the same area. Efficiency is important when there are vulnerable nestlings to feed.

Treecreepers are in a bird family of their own, but they are closely related to Nuthatches. They have stiff tails (like Woodpeckers) which enables them to prop themselves up against the bark. They are also very widespread, covering an area from Japan to Ireland, and with an estimated world population of 20 million birds. This makes it all the more astonishing that most of us have never seen one, but then their backs look like lichen-tangled wood. It’s their erratic, jerky movement that gives them away, that and their silvery white bellies, exposed briefly as they fly.

A few years ago I was lucky enough to visit Aigas, a Scottish estate which hosted wildlife-watching and writing courses. The Californian Redwood trees, which were planted in the grounds during Victorian times, were used as roosting places by the Treecreepers. The birds hollowed themselves out little sleeping niches in the soft bark, each about the size of a hard-boiled egg. Once, we took a walk around a roosting tree after dark with a torch, and found several birds, slumbering peacefully with their bottoms and tails protruding. Treecreepers also nest in shallow depressions in the tree trunks, often under a curtain of loose bark. This set me to wondering. In the Cemetery that abuts the wood, there are a number of Redwoods. Would I see any signs of Treecreeper activity there?

Well, I’m no expert so I wasn’t sure if the depressions in the trunk were made by Treecreepers or some other creatures, but whoever had made them had lined them up to face the rising sun, and the first warmth of the new day. I can imagine how welcome those sun rays would be after a long, cold night.

During the winter, Treecreepers can sometimes be found associating with flocks of tits, and it’s always worth surveying such groups carefully to see if there are any unusual birds in amongst them. However, it’s been found that the Treecreepers don’t share the food of the flock, and forage on their own – they are probably just benefiting from the extra eyes and ears of the other birds. Treecreepers strike me as being quite happy to keep themselves to themselves wherever possible.

In the spring, the Treecreepers pair up, and the female lays her five to six eggs, which are white with pink speckles. The babies are altricial (which means that they are completely helpless, unlike precocial birds which are fairly well developed at birth), so the parents have to work very hard to get them to the fledgling stage as quickly as possible. Their world is full of dangers – squirrels (both red and grey), woodpeckers, crows and martens will all eat the eggs and nestlings.  This is why the split foraging technique, where male and female search different parts of a tree, is so important. In coniferous forests, ants compete with the Treecreepers for their invertebrate food, and Treecreepers have learned to spend less time on trees which have large ant populations.

As I walked home from my trip to Coldfall Wood I was delighted to have been able to spend a few minutes with the Treecreeper. These birds remind me of forest spirits, elusive but ever-present, watchful and serious. It was a privilege to see them. I feel as if I will never get to the bottom of my half-mile territory, because there is always something new to see or learn. And I’m sure that this is true of any half-mile territory. The world truly is full of wonders.