Dear Readers, I like to think of myself as someone who is hopeful, but realistic. So, when I see those boards at the entrance to a nature reserve, describing all the wildlife that is lurking beyond the gate, I prepare myself for disappointment. Animals have a habit of moving around and not being where you expect to see them. Plants may not be in bloom, or may disappear completely. So whenever I’m told that there are nuthatches about, I breathe a long sigh. They are my nemesis. I have heard them many times. What I’ve never managed to do is to actually see them. So, when I was in Coldfall Wood last week and saw a small bird flash past and land in a tree down by the Everglades, I was not expecting him to stick around for some photographs. But, I was wrong!

Nuthatches are not uncommon birds – there are approximately 220,000 breeding couples in the UK, and they have a range from Portugal all the way to Japan. However, they are difficult to spot. You are much more likely to hear one – have a listen to the audio section on the RSPB page here. And one facet of their behaviour is unmistakable. Nuthatches are the only British birds that can run both up and down tree trunks – if you see a small bird hopping downwards, it’s a nuthatch.

Like Treecreepers and Woodpeckers , nuthatches forage beneath the bark of trees for their food, although they also eat seeds and, as you might expect, nuts. The bird jams an acorn or a hazelnut into a crevice in bark and bashes away at it with his ‘hatchet’-shaped bill. During the winter, the birds will cache nuts for use later on, and will hide them in plant-pots and window boxes, under stones, beneath bark and anywhere else that seems appropriate. Tests have shown that they can remember where they’ve left their caches for thirty days, which is impressive when I consider that some days I can barely remember where I’ve left my tube pass.

In the winter, nuthatches are another bird that might join a ‘feeding flock’ of finches or tits, but in the spring, the birds pair up for breeding.

Nuthatches are said to be monogamous, but, as in most things to do with the natural world, it ain’t that simple. A German study showed that ten percent of the chicks in the study area were fathered by a male who was not part of the ‘couple’, usually from an adjacent territory. Nuthatches are quite sedentary birds who need good quality woodland (which is increasingly short supply), and maybe the odd ‘illicit’ liaison helps to keep the gene-pool mixed up.

Nuthatches are yet another cavity nesting bird that lives in the wood – last week we talked about the Stock Doves that need hollow trees to nest, and when you add in the woodpeckers and the parakeets, it’s clear that the housing problem is about as acute as it is in the rest of London. However, having found a hole, nuthatches will make the entrance smaller if it’s too big, creating mortar from mud until way into the nest is a tight squeeze. The mud sets hard enough to deter even a woodpecker. Away from the nest, the nuthatch’s major predator is the sparrowhawk, that silent, round-winged killer of woodland birds. As usual, though, the major problem for nuthatches is the destruction of their habitat, another reason to be glad for the preservation of ancient woodland remnants like Coldfall.

Exploring Coldfall Wood reminds me of being in love. To start with, it was all about the obvious things – the scent of woodsmoke, the marsh marigolds, the parakeets squawking. But with every walk, I am noticing something different – the moods of the wood in rain and mist, the way the sounds change with the season, the arrival of some creatures and the departure of others.  Sometimes, the wood seems closed and unyielding, unwilling to share anything, and then I know that I have to be patient, and put in the time to really pay attention. At other times, the place seems abundant, full of wonders, with a new song bursting forth from every shrub, a new plant blooming under every tree. I never know what’s going to be happening when I set out, and I am starting to relax into the mystery of it all. Just as you never truly know another person, however long you live with them, so I will never know this few hectares of woodland. And that is the wonder of it .