What makes a bird a bird?
There are about 11 000 species of birds, from the tiny bee hummingbird (about 5 cm long) to the ostrich (up to 2.7 m tall). All birds share these features:
| Feature | Description |
|---|---|
| Feathers | Only birds have them |
| Beak | No teeth |
| Wings | Front limbs, though not all birds fly |
| Hard-shelled eggs | Laid and usually kept warm (incubated) |
| Warm-blooded | Keep a steady body temperature |
| Vertebrate | Have a backbone |
| Lungs with air sacs | Very efficient breathing |
Birds are living dinosaurs! They evolved from small feathered theropod dinosaurs about 150 million years ago. Archaeopteryx, a fossil with feathers, teeth and a bony tail, shows this link.
Built for flight
| Adaptation | How it helps |
|---|---|
| Hollow bones | Light but strong; supported by internal struts |
| Feathers | Shape wings, provide lift, reduce weight |
| Large breastbone (keel) | Anchors powerful flight muscles |
| Air sacs | Keep air flowing one way through the lungs for extra oxygen |
| No teeth; a gizzard instead | Lighter head; the gizzard grinds food |
| Fast metabolism | Lots of energy for flight |
Types of feathers
- Flight feathers on wings and tail give lift and steering.
- Contour feathers cover the body and give it a smooth shape.
- Down feathers are soft and fluffy, trapping warm air.
Birds replace worn feathers by moulting.
Beaks and feet tell a story
| Bird | Beak | Feet | Lifestyle |
|---|---|---|---|
| Eagle, hawk | Hooked, sharp | Strong talons | Hunts animals |
| Duck | Flat, wide | Webbed | Swims, filters food from water |
| Woodpecker | Chisel-like | Two toes forward, two back | Climbs trees, drills for insects |
| Hummingbird | Long, thin | Tiny | Sips nectar; hovers |
| Finch | Short, thick | Perching | Cracks seeds |
| Heron | Long, spear-like | Long legs | Wades and spears fish |
Life cycle
- Many birds court with songs, dances or colourful displays.
- They build nests of twigs, mud, grass or even spit (some swifts).
- Females lay eggs, and one or both parents incubate them.
- Chicks hatch. Some (like robins) are born helpless and blind; others (like ducks) can walk and swim within hours.
- Parents feed and protect the young until they fledge (leave the nest).
Migration
Many birds make long seasonal journeys called migration to find food and breeding sites.
- The Arctic tern makes the longest migration of any animal, roughly 70 000 km a year between the Arctic and Antarctica.
- Canada geese fly south in V-formations, saving energy by riding the air currents of the bird ahead.
- Birds navigate using the Sun, stars, Earth’s magnetic field and landmarks.
Canadian birds
The common loon appears on Canada’s one-dollar coin, the "loonie." The Canada jay (grey jay) was chosen by the Royal Canadian Geographic Society as a national bird in 2016, though it hasn’t been officially adopted. Other familiar birds include chickadees, blue jays, robins and snowy owls.
Birds that don’t fly
Penguins "fly" underwater with flipper-like wings. Ostriches and emus are fast runners. Kiwis in New Zealand have tiny wings hidden under their feathers.
Why birds matter
- They pollinate plants and spread seeds.
- They eat insects and rodents, controlling pests.
- Scientists use bird populations to measure the health of ecosystems.
Birds in trouble
North America has lost about 3 billion birds since 1970, more than a quarter of its bird population. Causes include habitat loss, pesticides, collisions with windows and buildings, and cats. You can help by keeping cats indoors, adding decals to windows and planting native plants.
Common mistakes
- Thinking all birds can fly.
- Thinking bats are birds. Bats are mammals with fur.
- Thinking birds are unrelated to dinosaurs.
Try it yourself
- Watch birds at a feeder for 15 minutes. Tally how many of each kind you see. Join a citizen-science count like Project FeederWatch.
- Compare a chicken bone with a beef bone (cooked, cleaned and cut by an adult). What’s different inside?
- Test beak shapes using tools: tweezers, chopsticks, a spoon and clothespins. Which "beak" picks up seeds, worms (rubber bands) or water best?
Quick recap
- Birds are warm-blooded vertebrates with feathers, beaks and hard-shelled eggs.
- Hollow bones, feathers and air sacs help them fly.
- Beak and foot shapes match what birds eat and how they live.
- Many birds migrate long distances.
- Birds descended from dinosaurs and are important to ecosystems.