Hummingbird eggs are the size of a jellybean. When the baby hummingbirds are born, they can be as small as .62 grams and 1 inch long. They are born without feathers, so the mother hummingbird needs to help them stay warm. Within a few days of being born, the baby hummingbirds double in size, and after a week they begin to have feathers.
Hummingbird behavior is very different from most other birds. They like to be alone and can become pretty mean towards other hummingbirds. Hummingbirds never fly in flocks. Male hummingbirds are very territorial. They will chase off other male hummingbirds that come into their territory. You will know when a hummingbird is fighting. They spread out their wings and the feathers on their tails so that they can look as big as possible. Then they use their claws and their beaks as weapons. Typically, hummingbirds fight in the air.
When a hummingbird sleeps, it falls into a hibernation-like sleep. During this time their body temperature and heart rate drops. If you look at a sleeping hummingbird, you will not even know it is breathing. They often sleep hanging upside down and look dead. You can even touch a hummingbird when it is sleeping, and it won't even notice you. Don't try this though, because it is still a wild animal.
Hummingbirds have many dangers that they face each and every day. One of the biggest dangers is the weather. They are very sensitive to temperatures and do not do well in extreme heat or cold. Sometimes heavy rains push a hummingbird into an ocean, lake or pond and it drowns. Hummingbirds also have a problem with predators, especially cats. Cats love to chase hummingbirds. They usually won't eat them, but will bat them out of the air and kill them.