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Biology – Nuthatch

Biology – Nuthatch

| On 31, Jul 2019

Darrell Mann

Like many people who watch birds, I have my favourites. The nuthatches that feed outside my office window for instance.

Quirky little birds. Shaped like stubby cigars, with their short tails, thick necks and their characteristic racing-stripe logo. And that disconcerting habit of spending time upside down. I wish I could do that. Of course, I wish I could walk up walls and hang from the ceiling like a gecko, too. But why do nuthatches walk down the trunks of trees, anyway? And, perhaps more importantly, why are they the only species of bird that does it?

“There’s no definitive answer to that,” said Cameron Ghalambor, a professor of biology at Colorado State University who has studied red-breasted nuthatches. The theory is the birds benefit from their different viewpoint. “You can imagine a creeper or a woodpecker facing the bark of a tree and looking up in the crevices of the bark for food items,” he said. “But there is this unexploited niche that you could access if you were working your way down the tree.”

Nuthatches store seeds in the bark of trees. Caching seeds so they can be seen going down the tree may keep them safe from other birds going up the tree, he said. “That’s a very important part of their winter diet. Starting in the fall they cache as many seeds as they can. Bird feeders have made their lives a little easier.”

Actually, Ghalambor explained, walking isn’t quite the correct word for what nuthatches do. “They look like they’re walking, but they sort of hang off the bark by the number one toe, also called the hallux, the backward-pointing toe…as they make their way down. It happens so quickly. It’s a very natural movement for them, but among birds it’s a very unique way of locomotion.”

Contradiction-wise, like most forms of nature, what all Nuthatch’s have evolved to do is be more Productive than their neighbours. What makes that difficult in this case is, a) competition from other species of birds, and b) the inability to detect food that might have fallen in to cracks and crevices. We can map the problem onto the Matrix as follows:

The strategy of facing down the tree rather than the conventional up-direction makes for a very nice illustration of Principle 13, The Other Way Around. The elongated hallux is then an equally nice illustration of either or both Principle 3, Local Quality, and Principle 4, Asymmetry.