You probably haven't seen what I've seen: an acrobat doing upside-down tricks in a tree, a highwayman with a black mask over his eyes stealing food in broad daylight, a singer with a song that rings out like a telephone in the middle of the woods, an English invader with designs on some new Scottish territory.

It is the nuthatch and the reason most people in Scotland won't have seen one is that this beautiful little bird is still, largely, an inhabitant of England. Except that milder winters are now attracting it to the south of Scotland more and more and the other day I saw one in my garden in Ayrshire for the first time.

I've been addicted to watching the nuthatch ever since because it really is a curious little creature.

Plump with a long head and short legs, it's about the size of a great tit but it has the self-assurance of something much bigger.

In it swoops, like it owns the place, takes a nut from the feeder and then heads up the tree where it sticks the nut in the bark and mercilessly splits it open.

Then it's back down the tree in a way that seems to say: look what I can do.

And quite right too because the nuthatch is the only bird that can go down a tree headfirst (you might want to write that fact down). The other birds always look on in awe.

Now what we should do is encourage this benign English invasion (with the use of peanuts) not only because the nuthatch looks wonderful but also because its presence, and its bring-bring song, is a reminder we shouldn't get over-concerned about the decline of birds in our garden. There may be a drop in some species but do not worry because another one will be along to replace it soon.

That is the law, as written by nature, and witnessed in my garden.