1. ostrich
   eagle
2. hawk

The ostrich is the largest bird in the world. The ostrich is also the fastest bird on the ground.

1. warm-blooded
2. cold-blooded

Birds are warm-blooded. They are not cold-blooded.

1. their bones are hollow
   their bones are straight
2. their bones are not actual bones, but cartilage

Bird bones are hollow. This helps them fly because their bones do not weigh much.

1. bears
   dogs
2. dinosaurs

Scientists believe that birds evolved from dinosaurs. Theropod dinosaurs had hollow bones.

1. yes
   no
2. who cares

Birds are not dumb. In fact, some birds are so smart they are able to use tools.

1. robin
   hummingbird
2. eagle

The bee hummingbird is the smallest bird in the world. The bee hummingbird is only about two inches long.

1. sparrow
   bluejay
2. homing pigeon

Homing pigeons are used to carry messages. They are specially bred to be able to find their way home.

1. 2
   4
2. 6

Bird hearts have four chambers. This is the same as a human.

1. rainforests
   New York City
2. London

Although it may seem like most birds live in New York City, most bird species actually live in tropical rainforests. In fact, as many as two-thirds of all bird species live in tropical rainforests.

1. heart
   brain
2. bladder

Birds do not have bladders. Their waste is mixed together and excreted at the same time.

1. brain
   feet
2. lungs

Compared to humans, birds have larger lungs. In humans, the lungs take up roughly five percent of the body; in birds, the lungs take up roughly 20% of the body.

1. head
   eyes
2. tails

Owls swivel their necks completely around to see things behind them. This is because owls can't swivel their eyes.

1. cat
   dog
2. fish

In the U.S., cats kill as many as four billion birds every year. So, yes, your fluffy cat really does want to go outside and bring back a bird for dinner.

1. hummingbird
   sparrow
2. owl

The hummingbird is the only bird that can fly backward. The bee hummingbird is only about two inches long.

1. canary
   eagle
2. falcon

Coal miners used canaries to check for dangerous gases. This is where the saying "canary in a coal mine" came from.

1. 2.5 gallons
   1 quart
2. 100 pints

A pelican's beak can hold up to 2.5 gallons of water. The pouch contracts to push out the water before the pelican swallows its prey.

1. knee
   ankle
2. hip

Bird's legs bend backward at the ankle. It looks like the knee, doesn't it?

1. ostrich
   eagle
2. hummingbird

The ostrich lays the biggest eggs. Ostrich eggs weigh as much as three pounds.

1. owl
   eagle
2. hummingbird

The hummingbird has only about 1,000 feathers. This is because its body is so small. Bigger birds have more feathers.

1. malleefowl
   owl
2. eagle

The malleefowl lays its eggs in compost. The heat from the compost helps keep the eggs warm.

1. robin
   weaverbird
2. eagle

Weaverbirds may live in huge nests with up to 400 other birds. The nests are so large that they can weigh up to several tons.

1. because they eat shrimp
   they are born pink
2. Only old flamingos are pink.

Flamingos are not born pink. They turn pink because of the amount of beta carotene in their diets.

1. condor
   owl
2. bat

The Andean condor is the heaviest bird of prey. The Andean condor can weigh almost 30 pounds.

1. albatross
   sparrow
2. hummingbird

The wandering albatross can live up to 80 years. In general, the larger the bird, the longer it lives.

1. hummingbird
   eagle
2. owl

The bee hummingbird lays the smallest eggs. Bee hummingbird eggs weigh only 0.02 ounces.

1. eagle
   penguin
2. sparrow

The Gentoo penguin can swim faster than 20 miles per hour. The Emperor penguin can stay underwater the longest.

1. sparrow
   tern
2. eagle

The arctic tern migrates more than 25,000 miles every year. The tern migrates from the arctic to the antarctic every year.

1. albatross
   eagle
2. robin

The albatross has the greatest wingspan. The wings of an albatross can span almost 12 feet wide.

1. vulture
   sparrow
2. hummingbird

The Griffon vulture can fly the highest. The Griffon vulture has been spotted at elevations of almost 7 miles.

1. hummingbird
   sparrow
2. ostrich

Ostrich females willing tend other ostrich females' eggs. They are the only birds to do so.

1. elephant bird
   hummingbird
2. crow

The elephant bird is the biggest bird to ever exist. It is extinct, but it is though to have weighed as much as 1,000 pounds.

1. penguin
   hummingbird
2. crow

The emperor penguin is the only bird to lay its eggs in the winter. The hatchlings need more time to grow strong enough to survive the next winter.

1. falcon
   sparrow
2. robin

The peregrine falcon can dive at speeds of more than 180 mph. Their prey doesn't stand a chance.

1. owl
   sparrow
2. oilbird

The oilbird is the only bird to use echolocation, like bats. The oilbird is also the only nocturnal, fruit-eating bird.

1. flamboyance
   murder
2. parliament

A group of flamingos is called a flamboyance. A group of crows is called a murder. A group of owls is called a parliament.