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Why can't chickens fly?

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📓 The short answer

Chickens actually can fly, but their body structure and selective breeding limit them to short bursts rather than sustained flight. Certain farming practices also intentionally or unintentionally hamper their flying capabilities.

📚 The long answer

Let me stop you right there: Chickens can fly!

They just can't fly that well. When they do, it’s typically only a brief burst upward rather than sustained flight.

Now that we've busted the myth of the flightless chicken, here are some reasons why chickens can't fly ... very well:

Reason #1: Modern chickens are closely related to the jungle fowl.

Today's chickens are closely related to the jungle fowl, a wild bird native to South and Southeast Asia.

Jungle fowl can take short vertical flights but mostly live on the ground, using their wings to reach trees for safety or sleep. This is why their wings are smaller than other birds and their feet aren't well suited for perching on trees.

Chickens share these characteristics with jungle fowl, primarily living on the ground with the occasional, short flight.

Reason #2: Chickens have been selectively bred for meat production to have large breast and thigh muscles.

Over the years, chicken meat consumption has grown—and so has chicken meat.

According to the National Chicken Council, the average American consumed over 100 pounds (~45 kg) of chicken meat in 2022, more than twice the amount consumed in 1983.

But it's not just that people are eating more chickens, it's that we've selectively bred chickens to have abnormally large breast and thigh muscles. Selective breeding is responsible for 85-90% of the increase in chicken body weight between 1957 and 1991.

Chickens have been bred for larger breast muscles and thicker thighs, as these cuts are most popular. But their oversized muscles make flight nearly impossible. In fact, most broiler chickens (bred for meat consumption) spend 90% of their lives lying down, unable to support their weight.

In order for birds to fly, they need a certain "wing loading" ratio, the proportion of body mass to wing area. Birds need to have at least 1 square inch of wing for every 0.6 ounce of body mass (1 square centimeter per 2.5 grams) to fly. When chickens are bred to be unnaturally heavy, they exceed the optimal wing loading ratio and struggle to take off.

Reason #3: Certain backyard and factory farming practices — like wing clipping and forced molting — reduce feather area.

There are also some common farming practices that intentionally or unintentionally keep chickens from flying.

Wing clipping prevents chickens from flying

In backyard chicken farming, wing clipping is commonly used to prevent chickens from escaping their fenced area. With clipped wings, chickens struggle or fail to fly.

When done correctly, this practice is painless for the chicken, but it can result in falls due to balance issues and psychological distress.

While wing clipping is common in the United States, it is generally avoided in European countries, where it is considered a form of animal cruelty. Wing clipping is also less common in factory farming as chickens typically have no risk of escaping due to being contained in packed chicken houses or cages.

Forced molting decreases the feather area of hens

As hens age, their egg production naturally slows down. In the United States, it's common to increase production by intentionally starving or feeding the hen low-nutrient food for up to two weeks. This process causes the hen to shed their feathers (known as molting) and lose up to 30% of their body fat. When the hens' diet returns to normal, it stimulates a final surge in egg production that results in larger, more profitable eggs before the hens are slaughtered.

The reduced feather coverage caused by forced molting makes flight nearly impossible for these older hens. Although this practice is banned in the European Union for animal welfare reasons, it remains legal in the United States.

--- Thanks for reading this week's newsletter! If you have any thoughts, questions, or favorite GIFs, my inbox is always open. Just hit reply to send me a note! :) ​ All my best, Caitlin ​Click here to read five facts about Caitlin​

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​Sources for this week's newsletter​

NEW! 🌐 Wikipedia article of the week

​Chicken eyeglasses​

"Chicken eyeglasses...were small eyeglasses made for chickens intended to prevent feather pecking and cannibalism....One variety used rose-colored lenses, as the coloring was thought to prevent a chicken wearing them from recognizing blood on other chickens, which may increase the tendency for abnormal injurious behavior. They were mass-produced and sold throughout the United States as early as the beginning of the 20th century."

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👀 Catch up on other curious questions

• ​Why don’t woodpeckers get brain damage?​​
• ​Why does getting hit while cold hurt more?​​
• ​Why do we eat cake on birthdays?​​

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