Why do nuthatch birds walk upside down?

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📓 The short answer

Nuthatches climb down trees headfirst to forage more efficiently. By approaching the bark from above, they can spot hidden food that upward-climbing birds may miss.

📚 The long answer

Say hello to the nuthatch. 🙃👋

While some other birds, like woodpeckers and brown creepers, can climb up a tree, nuthatches are one of the only birds in the world that can climb headfirst down a tree. (In case you're wondering, the black-and-white warbler is the other gravity-defying bird.)

How do nuthatches walk upside down?

It's the nuthatches' anatomy that allows them to walk upside down. Their body weight is centered thanks to a short tail, making them a balanced little round ball.

And they're able to grip all the nooks and crannies of tree bark with their strong feet and narrow, sharp claws. Nuthatches have four toes, three facing forwards and one facing backwards. Their backward-facing toe is especially strong and helps them cling to bark while facing downward.

Other tree-climbing birds use a different approach. Woodpeckers, for instance, grip the tree bark and then use their long tail feathers to brace themselves, like a tripod. This stable setup sacrifices some mobility in exchange for power, so the woodpecker can do what woodpeckers do best.

Why do nuthatches walk upside down?

Nuthatches have clearly evolved to walk up, down, and around trees. But what is the point of all this gravity-defying walking? Here are three reasons why nuthatches walk upside down.

Reason #1: Nuthatches spot food missed by other birds.

Nuthatches have carved out a lucrative niche in the tree-foraging bird community. One likely advantage of walking down trees is that nuthatches can spot food in bark crevices that upward-moving birds might miss.

Like woodpeckers and brown creepers, nuthatches primarily eat insects found in the crevices of tree bark, especially in the warmer months. So to avoid the heavy competition, nuthatches go for the unexploited niche of looking down.

Some nuthatches even use tools, carrying pieces of bark as levers to pry up bark to look for even more untapped food sources.

Reason #2: Nuthatches effectively hide seeds in tree bark.

Insects get harder to come by as the seasons start to change, so nuthatches find more uses for the tree bark as food storage. Nuthatches cache seeds in bark crevices, often covering them with bark or lichen. They have been observed retrieving their hidden seeds, giving them a ready food supply throughout the winter.

Reason #3: Nuthatches use tree bark to help them crack open seeds.

And now we get to how the nuthatch got its name. While facing the ground, a nuthatch often wedges a seed or nut into a crevice in tree bark, then hammers it open with its bill to reach the food inside. The name nuthatch comes from Middle English words meaning roughly “nut hacker,” referring to the bird’s habit of wedging nuts into bark and hacking them open.

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​Sources for this week's newsletter​

🌐 Wikipedia article of the week

​Penn & Teller's Smoke and Mirrors​

"Penn & Teller's Smoke and Mirrors is a canceled minigame compilation developed by Absolute Entertainment and starring the magician duo Penn & Teller. It comprises six minigames used to play practical jokes on others: Two party tricks, two multiplayer "scams" in which one player can unfairly influence or interrupt the gameplay, the beat 'em up Smoke and Mirrors, and Desert Bus, in which the player must drive a bus over an empty, straight road for eight hours to score one point."

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