Tail-or Made For Flight

That's one long...tail

Many people, myself included, often wish they had a tail. Wouldn’t it be cool to have an extra functional limb? Well, birds are one of the lucky animals that do have tails. However, they’re often overlooked because humans are so fascinated by their wings. Humans can fully function without tails, but the opposite is actually true for birds. Without their tail feathers, flying would be a pretty difficult chore.

Tails are actually integral to bird flight. But if a bird’s wings produce the lift, where do the tails come in? Well, its tail feathers are analogous to the rudders of ships and boats. They help them steer and maneuver while flying, as well as provide stability as they take-off and land. By twisting its tail, the bird can change its direction mid-flight.

Tails are analogous to rudders

To help the bird slow down, the tail flares out downward, creating more drag and decrease the bird’s velocity. The tail also helps the bird balance when it is perched on a branch. And while the bird is soaring, it can spread out its tail feathers behind it to create additional lift and stability.

The tail consists of a central shaft and vanes of interlocked feathers. Tail feathers themselves are light and stiff, designed to push against air to create lift. Birds can use their tail feathers to help pitch their bodies and adjust their altitude, similar to rudders on airplanes.

Tail as a brace

Tails can have other specific functions depending on the species of the bird. Birds like woodpeckers and woodcreepers have extremely stiff tails that help brace themselves against tree trunks. Peacocks and lyrebirds have huge, colorful tails that they use to attract mates.

Scientists have even found that hummingbirds actually use their tails to “sing”.

Chick magnet

Air flows past the tail feather, creating a flutter-induced sound, similar to how blowing a single blade of grass can produce a whistling sound. These aeroelastic flutters help the male hummingbirds attract females. So not only do tails help many birds fly, they also help some of them find mates.

Some scientists have used delta-wing theory to explain how their birds’ tails work. The delta wing is a triangular wing platform that is swept back, and is typically used for military aircraft.

Delta Wing

Recently, scientists like Matthew R. Evans, from the University of Stirling, have concluded that bird tails do act like delta-wings, but only under some conditions; specifically, at angles of attack of less than 20 degrees and tails spread under 60 degrees.

So overall, it looks like tails are not just there for decoration, even for peacocks (Yes, they fly! But only for short distances). It’s hard to imagine what flying without a tail would look like; it’s certainly possible for certain species of birds to fly without tails, but it’s obvious that flying would be much harder to control for even the most athletic birds without the use of a tail.


One Comment

Lorena Barba posted on November 4, 2012 at 4:49 pm

The You Tube video embedded in your second source (The New York Times) is very interesting: the scientist from Yale University explains the singing tails of Anna’s hummingbird:

Also, if you look at the documentary about SmartBird, the first prototype failed …
(watch until 13:00) … it turned out, the tail had a big role in the success of the revised prototype!