baodaweistar 2008-6-2 23:44
JJ中常提到的hummingbird英文资料
[b]Hummingbirds[/b] are birds of the [url=http://en.wikipedia.org/wiki/Family_%28biology%29][color=#0066cc]family[/color][/url] [b]Trochilidae[/b], and are native only to the [url=http://en.wikipedia.org/wiki/Americas][color=#0066cc]Americas[/color][/url]. They are known for their ability to [url=http://en.wikipedia.org/wiki/Hover][color=#0066cc]hover[/color][/url] in mid-air by rapidly flapping their [url=http://en.wikipedia.org/wiki/Wing][color=#0066cc]wings[/color][/url] 15–80 times per second (depending on the species). Capable of sustained hovering, hummingbirds also have the ability to fly backward, being the only group of birds able to do so[url=http://en.wikipedia.org/wiki/Hummingbird#cite_note-0][color=#0066cc][1][/color][/url]. Hummingbirds may also fly vertically and laterally. Their English name derives from the characteristic [url=http://en.wikipedia.org/wiki/Hum_%28sound%29][color=#0066cc]hum[/color][/url] made by their wings.
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Hummingbirds are small birds with long, thin [url=http://en.wikipedia.org/wiki/Beak][color=#0066cc]bills[/color][/url]. The bill combined with an extendable, [url=http://en.wikipedia.org/wiki/Forked_tongue][color=#0066cc]bifurcated tongue[/color][/url], has [url=http://en.wikipedia.org/wiki/Evolution][color=#0066cc]evolved[/color][/url] in order to allow the bird to feed upon [url=http://en.wikipedia.org/wiki/Nectar][color=#0066cc]nectar[/color][/url] deep within flowers. The bill can be opened wide, and the lower half ([url=http://en.wikipedia.org/wiki/Mandible][color=#0066cc]mandible[/color][/url]) also has the ability to flex downward to create an even wider opening, facilitating the capture of flying insects in the mouth rather than at the tip of the bill.[url=http://en.wikipedia.org/wiki/Hummingbird#cite_note-1][color=#0066cc][2][/color][/url]m1o.W` x9s }9y
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Hummingbirds feed on the [url=http://en.wikipedia.org/wiki/Nectar_%28plant%29][color=#0066cc]nectar[/color][/url] of plants and are important [url=http://en.wikipedia.org/wiki/Pollinator][color=#0066cc]pollinators[/color][/url], especially of deep-throated, tubular flowers. Like bees, they are able to assess the amount of sugar in the nectar they eat; they reject flower types that produce nectar which is less than 12% sugar and prefer those whose sugar content is around 25%. Nectar is a poor source of [url=http://en.wikipedia.org/wiki/Nutrients][color=#0066cc]nutrients[/color][/url], so hummingbirds meet their needs for [url=http://en.wikipedia.org/wiki/Protein][color=#0066cc]protein[/color][/url], [url=http://en.wikipedia.org/wiki/Amino_acids][color=#0066cc]amino acids[/color][/url], [url=http://en.wikipedia.org/wiki/Vitamins][color=#0066cc]vitamins[/color][/url], [url=http://en.wikipedia.org/wiki/Minerals][color=#0066cc]minerals[/color][/url], etc. by preying on [url=http://en.wikipedia.org/wiki/Insect][color=#0066cc]insects[/color][/url] and [url=http://en.wikipedia.org/wiki/Spider][color=#0066cc]spiders[/color][/url], especially when feeding young. pg7c&b C1B1aol
Most hummingbirds have bills that are long and straight or nearly so, but in some species the bill shape is adapted for specialized feeding. [url=http://en.wikipedia.org/wiki/Thornbill][color=#0066cc]Thornbills[/color][/url] have short, sharp bills adapted for feeding from flowers with short [url=http://en.wikipedia.org/wiki/Corolla_%28flower%29][color=#0066cc]corollas[/color][/url] and piercing the bases of longer ones. The [url=http://en.wikipedia.org/wiki/Sicklebill][color=#0066cc]Sicklebills[/color][/url]' extremely decurved bills are adapted to extracting nectar from the curved corollas of flowers in the family [url=http://en.wikipedia.org/wiki/Gesneriaceae][color=#0066cc]Gesneriaceae[/color][/url]. The bill of the [url=http://en.wikipedia.org/wiki/Fiery-tailed_Awlbill][color=#0066cc]Fiery-tailed Awlbill[/color][/url] has an upturned tip, as in the [url=http://en.wikipedia.org/wiki/Avocet][color=#0066cc]Avocets[/color][/url]. The male [url=http://en.wikipedia.org/wiki/Tooth-billed_Hummingbird][color=#0066cc]Tooth-billed Hummingbird[/color][/url] has barracuda-like spikes at the tip of its long, straight bill.N;~;@~7K
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With the exception of insects, hummingbirds while in flight have the highest [url=http://en.wikipedia.org/wiki/Metabolism][color=#0066cc]metabolism[/color][/url] of all animals, a necessity in order to support the rapid beating of their wings. Their [url=http://en.wikipedia.org/wiki/Heart_rate][color=#0066cc]heart rate[/color][/url] can reach as high as 1,260 beats per minute, a rate once measured in a [url=http://en.wikipedia.org/wiki/Blue-throated_Hummingbird][color=#0066cc]Blue-throated Hummingbird[/color][/url] [url=http://www.hummingbirds.net/about.html#heartbeat][color=#0066cc][1][/color][/url]. They also typically consume more than their own weight in nectar each day, and to do so they must visit hundreds of flowers daily. At any given moment, they are only hours away from starving.
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However, they are capable of slowing down their metabolism at night, or any other time food is not readily available. They enter a [url=http://en.wikipedia.org/wiki/Hibernation][color=#0066cc]hibernation[/color][/url]-like state known as [url=http://en.wikipedia.org/wiki/Torpor][color=#0066cc]torpor[/color][/url]. During torpor, the heart rate and rate of breathing are both slowed dramatically (the heart rate to roughly 50–180 beats per minute), reducing their need for food. Most organisms with very rapid metabolism have short lifespans; however hummingbirds have been known to survive in captivity for as long as 17 years.9K0Y3T
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The dynamic range of metabolic rates in hummingbirds (Suarez and Gass 2002) requires a corresponding dynamic range in kidney function (Bakken et al. 2004 The glomerulus is a cluster of capillaries in the nephrons of the kidney which removes certain substances from the blood; a filtration mechanism. The rate at which food is metabolized is called the glomerular filtration rate (GFR). Most often these fluids are reabsorbed by the kidney. During the night hummingbirds undergo a state of dormancy called torpor. To prevent dehydration, the GFR slows, preserving necessities for the body such as glucose, water and salts. GFR also slows down when the birds are undergoing water deprivation. The interruption of GFR is a survival and physiological mechanism unique to hummingbirds (Bakken et al 2004).
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Studies of hummingbirds' metabolism are highly relevant to the question of whether a [url=http://en.wikipedia.org/wiki/Bird_migration][color=#0066cc]migrating[/color][/url] [url=http://en.wikipedia.org/wiki/Ruby-throated_Hummingbird][color=#0066cc]Ruby-throated Hummingbird[/color][/url] can cross 800 [url=http://en.wikipedia.org/wiki/Kilometre][color=#0066cc]km[/color][/url] (500 [url=http://en.wikipedia.org/wiki/Statute_mile][color=#0066cc]miles[/color][/url]) of the [url=http://en.wikipedia.org/wiki/Gulf_of_Mexico][color=#0066cc]Gulf of Mexico[/color][/url] on a nonstop flight, as field observations suggest it does. This hummingbird, like other birds preparing to migrate, stores up fat to serve as fuel, thereby augmenting its weight by as much as 100 percent and hence increasing the bird's potential flying time.[url=http://en.wikipedia.org/wiki/Hummingbird#cite_note-Skutch.2C_1973-8][color=#0066cc][9][/color][/url]
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[size=5]Hummingbirds and humans[/size]^ |QuP,c
Their relatively small size, brilliant colors, fearless personalities, and remarkable mode of flight have won hummingbirds nearly universal admiration from humans. They do not harm crops or livestock, make loud noises, foul cars or buildings with their droppings, or bite when handled, making them among the most benign of all birds.
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Hummingbirds have not always benefited from this admiration. Their beauty and novelty made them popular with commercial and scientific collectors in the 19th century; many fashionable parlors were decorated with glass cases containing preserved specimens of hummingbirds and other colorful tropical species. Their demanding dietary requirements and high metabolism kept them from becoming popular as pets, though many have been imported into Europe and the United States for zoos and private aviaries.
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Habitat destruction and climate change are the most pervasive threats to all hummingbirds, but other human-related causes of hummingbird mortality include pesticide poisoning; collisions with windows, cars, utility lines, and transmission towers; predation by domestic cats; electrocution on electric fences; and entanglement in the hooked spines of [url=http://en.wikipedia.org/wiki/Burdock][color=#0066cc]burdock[/color][/url], an alien weed. \
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Hummingbirds sometimes fly into buildings, especially [url=http://en.wikipedia.org/wiki/Garage_%28house%29][color=#0066cc]garages[/color][/url], possibly while investigating brightly colored objects such as flower arrangements, floral draperies, and emergency release handles for automatic garage doors. Once inside, they may be unable to escape because their natural [url=http://en.wikipedia.org/wiki/Instinct][color=#0066cc]instinct[/color][/url] when threatened or trapped is to fly upward. This is a life-threatening situation for hummingbirds, as they can become exhausted and die in a relatively short period of time, possibly as little as an hour. It is usually difficult to catch a trapped hummingbird until it is exhausted, and handling such small birds requires extreme delicacy of touch. Sometimes a trapped hummingbird will land on a broom or a long branch if it is moved very carefully into a position near the bird. Once relaxed on the perch, the bird may remain long enough to allow itself to be carried outside to safety. A more time-consuming but less traumatic alternative is to place a feeder near where the trapped bird is flying or perching, waiting until it begins using the feeder, then moving the feeder a few feet at a time toward an open door or window. Once the feeder is hanging in the opening, the bird should notice the escape route on its own.
九九八十一 2008-6-3 16:47
谢谢,发现这只鸟还真是到处都能看到,G的阅读,T的也是....烦人的很..HOHO
Horse 2008-6-4 02:43
当成背景好好了解 一下，就算不是为了托福考试，也可以为自己的知识面做扩充嘛/d+^P tO,yY'a1gIk
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同时多去按照jj里提到的频繁的话题去看看百科全书，也在另外一个方面提高了自己的英语的阅读能力
