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The introduction of hummingbirds (蜂鸟的介绍,转载)  

2010-12-01 11:28:52|  分类: 8A U4--U6 |  标签: |举报 |字号 订阅

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Few birds have been as little studied and as misunderstood as Hummingbirds. They are the smallest of all birds with a length ranging from 2" to 8". Males of most species are identified by their iridescent feathers. Females and immatures of both sexes are normally plain and nondescript with the immatures of both sexes resembling the adult females.

 

Hummingbirds are strictly a bird of the Western Hemisphere. They are found as far north as Southeastern Alaska and the Maritimes of Canada and as far south as Southern Chile. The majority of the approximately 320 species are found in the tropics. 

 

Only 15 species have been known to breed in North America with another 6 being classified as vagrants. Until recently, for instance, it was thought that Ruby-throated hummingbirds were essentially the only species of hummingbird found east of the Mississippi River.

 

WHAT DO THEY LOOK LIKE? 

 

Hummingbirds are the world’s smallest birds.  It’s only 3 ? inches long!  These tiny birds have shiny green backs & white bellies.  Boys have bright ruby-red throats and forked tails.  The girl’s throats are white, and their tails are straight.

 

WHAT DO THEY EAT?

 

 Hummingbirds (hummers) usually drink nectar (sugar water) from flowers.  While the hummer is drinking the flower’s nectar, some pollen sticks to the hummer’s chin.  The pollen falls off at the next flower it visits, and PRESTO, the flower is pollinated, ready to make seeds!   Flowers give food to hummers, and hummers help the flowers to make seeds.  This natural cooperation is called symbiosis (sim-bee-O-sis).  Hummingbird flowers are usually long, red, and skinny, to match the hummer’s long beak and tongue.  But hummers need more than just sugar to survive.  They also need protein.  That’s why they eat small bugs inside flowers, and sometimes pick bugs out of spider webs for food.  In early spring, before the flowers bloom, hummers will follow Yellow-bellied Sapsuckers.  These woodpeckers peck holes in trees to get sap.  The hummer can lick the sap and eat the bugs around these holes!

 

HOW DO THEY FLY? 

 

Instead of flapping their wings like most birds, hummers move their wings back and forth like a swimmer.  This helps them hover, or hang in the same place in the air.  They can fly forwards, sideways, and even backwards!  They’ve been clocked at speeds faster than 45 mph!  The hummers that live in Florida migrate (fly) from here all the way across the Gulf of Mexico to Texas.  Hummers have to eat enormous amounts of nectar before they leave, gaining 50% of their body weight in fat. Even when they’re not migrating, hummers use so much energy flying that they have to eat almost every ten minutes to stay alive!  Many people put out hummingbird feeders with 1:4 sugar water inside.  Feeders have red parts to attract the hummers.  You have to clean the feeder & change the sugar water every 2 days or it will spoil in the heat & the hummers won’t eat it.  (Don’t use honey; it makes hummers sick!)

 

WHAT ABOUT BABY HUMMINGBIRDS? 

 

Male hummers set up a territory near good nectar flowers, and won’t let any other hummers inside their territory, and they’ll even chase away blue jays, bees, and large moths.  While the male is defending his territory, the female spends 1 week building a nest out of spider webs, plant fluff, and lichens.  The whole nest is less than 2 inches wide.  When her nest is ready, she flies to the male’s territory to mate.  He does not help to raise the babies at all.  She lays 2 white eggs about ? the size of jelly beans.  As they grow, the babies get too big for the nest, but since it is made of stretchy spider webs, the nest will stretch to fit around the babies.  By the time they are a month old the young hummers are beginning to fly and can find food for themselves.

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