Read the passage carefully and answer the question:
Have you ever heard the sound of a hummingbird? They make a buzzing noise when they fly. They make this noise because they beat their wings so fast. They beat their wings up to 80 times a second. All that flapping makes a lot of noise. That's why we call them hummingbirds. Hummingbirds fly in a unique way. They move their wings so fast that they can hover. This means that they can stay in one spot in the middle of the air, like a helicopter. Sometimes they fly or hover upside down. They are the only bird that flies backward. Hummingbirds are small. One type called the bee hummingbird is the smallest bird in the world. Bee hummingbirds weigh less than a penny. They are just a little bit bigger than bees. I guess that's where they get their name. Bee hummingbirds build tiny nests. They use cobwebs and bits of bark to make their homes. Their homes are only an inch around. This is big enough for their eggs though. Their eggs are smaller than peas. People have found these tiny nests on a clothespin. Hummingbirds move fast. It takes lots of energy to move as fast as they do. This means that they need to eat a lot of food. Their favorite food is nectar, a sweet liquid inside of some flowers. They drink more than their own weight in nectar daily. They have to visit hundreds of flowers to get enough nectar to live. They can only store enough energy to survive through the night. They live on the edge. Hummingbirds don't use their long beaks like straws. They have a tongue just like you. They use their tongues for eating. They flick their tongues in and out of their mouths while inside of flowers. They lap up nectar. Flowers give them the energy that they need. Hummingbirds help flowers too. They get pollen on their heads and bills when they feed. Flowers use pollen to make seeds. Hummingbirds help pollen get from one flower to the next. This helps flowers make more seeds. More seeds means more flowers. More flowers means more food for hummingbirds. Isn't it nice how that works out?
Why are they called hummingbirds?