Canada geese in migration.

Your Bird Questions Answered: Flight and Migration

Canada geese in migration.
Canada geese in migration.

How do birds fly? How fast do they fly? And where do birds sleep? These are all good questions, and they deserve good answers. Thankfully, the birding experts at Bird Watcher’s Digest have some good answers! Here are some of the interesting questions that people often ask about birds.

Learn the answers to these questions:

  • What makes a bird a bird?
  • How do birds fly?
  • How fast do birds fly?
  • Do birds fly at night?
  • Why do birds migrate?
  • How do birds know where to go when they migrate?
  • Where do birds sleep, and how do they survive severe weather conditions?

What makes a bird a bird?

The first thing most people notice about birds is that they can fly, but that is not what makes them unique. Bats, bugs, and butterflies also take to the air, and they aren’t birds. What makes birds different from every other kind of animal on earth are feathers.

Feathers make it possible for birds to live a large part of their lives in the air. Feathers weigh very little, are strong (to survive long flights), and provide terrific insulation (which is why people living in the coldest parts of the world prefer jackets stuffed with goose down). Most birds also have hollow bones. If bird bones were solid, like human bones, birds would be too heavy, which would make flight very difficult.

How do birds fly?

The simple answer is: with their wings. A more accurate answer is that everything about a bird’s body is designed for flight, including its specialized feathers, hollow bones, and very strong flight muscles located in the breast. As a bird flaps its wings, the force of the wings does two things: lifts and propels the bird.

As the wings push downward and backward, more air is moved below the wing than above it. This difference in the amount of air, or air pressure, is what causes lift, and results in upward and forward movement of the bird.

The concept of lift, such as that produced by a bird’s wing, can be illustrated easily. Hold your hand, flattened with fingers together, just outside the window of a moving car. When the leading edge of the hand tilted upward, the force of the wind immediately pushes the hand upward. This is exactly how the aerodynamic design of a bird’s wing helps to create life and helps to hold a bird in the air in between flaps or while gliding.

How fast do birds fly?

Although they seem very fast to us, most birds do not fly more than 30 or 40 miles per hour at top speed. In general, small birds fly slower, and big birds fly faster. Birds as small as sparrows probably fly less than 20 miles per hour while some of the hawks fly as much as 50 or 60 miles per hour.

We don’t know much about how fast birds fly because it is very hard to measure. Improvements in technologies such as radar will probably allow us to answer some of these questions in the future.

Do birds fly at night?

Most birds can fly at night, but will only do so if necessary. The reason for this is that their eyes, like human eyes, are not designed to see in nighttime conditions. If a bird cannot see well, it risks injury by flying at night. Unless startled into flight by a predator, most birds will avoid leaving their nighttime roost.

Other species, such as owls and nightjars (nighthawks and whippoor-wills) fly primarily at night, their most active time, and sleep during the day. Songbirds, such as warblers and tanagers, which are active during daylight hours, do fly at night during migration, when they must travel long distances. It is thought that these migrants fly at night because the air is cooler, so there is less chance of their overheating during the long, strenuous periods of flight.

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Why do birds migrate?

Not all birds migrate. Some, such as cardinals, live their whole lives within a fairly small area. Many birds migrate long distances, however. Birds migrate primarily for two reasons, to avoid bad weather and to find food.

Many geese and ducks leave the north in winter because the water there freezes, and these birds need open water to survive. Warblers, which eat mostly insects, leave North America and go south to the tropics, because there is no food for them in the north in winter.

How do birds know where to go when they migrate?

This question has fascinated scientists for centuries, and we are only beginning to know how some birds find their way during long migrations. Birds are born knowing that they must migrate, but knowing that is not the same as knowing how to get from a woodlot in Wisconsin to a jungle in Brazil or from a sea cliff in Alaska to a feeding ground in the Antarctic.

We know that some birds are born with a “star map” coded into their brains that allows them to navigate by the position of the stars and the moon. Some birds use the earth’s magnetic field to find their way, and some use subsonic sound, the low-level noise created by ocean waves.

Still others, like geese and swans, make their migrations in family groups, led always by an older bird that has made the flight before. There is still much to learn, however, about how birds make such long flights and find precisely the right spot.

How long does it take for a hummingbird to migrate and how far do they migrate?

A hummingbird’s migration varies depending on the species. For this question, we’ll choose the ruby-throated hummingbird, the most common hummingbird in North America.

The majority of ruby-throated hummingbirds spend the winter in Central America, between southern Mexico and Panama, although some birds may stay in Texas along the Gulf Coast. Most birds migrating to Central America will fly the 500 miles across the Gulf of Mexico, leaving at dusk, which takes between 18 and 22 hours.

In the spring, ruby-throated hummingbirds will migrate to North America and spend the summer anywhere between Texas and Florida to southern Canada. For a bird migrating from Panama to southern Canada that’s more than 2,000 miles! As an average, it takes hummingbirds about two weeks to migrate.

Where do birds sleep, and how do they survive severe weather conditions?

Before falling asleep, most birds seek shelter from predators and weather. This is vital to their survival because a sleeping bird is more vulnerable to danger.

As you might imagine, each species has a technique of locating shelter as unique as its methods of finding food, and this varies based upon options available in the environment. Cavity nesters (bluebirds, chickadees, titmice, some woodpeckers and swallows, for example), tend to roost in enclosed areas such as tree hollows, bird houses, caves, or culverts.

Sparrows, warblers, thrushes, and other songbirds frequently roost for the night amid thick vegetation. At all times, it’s important that they remain concealed from owls, raccoons, snakes, and other predators.

During cold or rainy weather, most birds avoid direct wind by sheltering underneath protective overhangs found in an evergreen tree, vine tangle, thick brush, or deep grass.

2 thoughts on “Your Bird Questions Answered: Flight and Migration”

  1. Southwest Florida question: Past 3 weeks there have been huge birds gliding the wind currents around Sarasota County. Which type of birds are these & why do they do it? It does not appear to be food or migration related? Thank you

    1. Hi Elle, I can’t really say what kind of birds they were without knowing more. Were they above land or water? Were they hawks? Vultures? Pelicans? Frigatebirds? Even if they’re not actively feeding or hunting, they might be looking for food sources, or safe roosts, or they might just be … “hanging out.” Gliding on the wind doesn’t take much energy. Any chance you can get a photo of these birds? Even a bad photo is better than none for making an ID. Dawn Hewitt, Bird Watcher’s Digest

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