DEER AND THE ENERGY CYCLE

    Some persons say that love makes the world go round. Others of a less romantic and more practical turn of mind say that it isn\'t love; it\'s money. But the truth is that it is energy that makes the world go round. Energy is the currency of the ecological system and life becomes possible only when food is converted into energy, which in turn is used to seek more food to grow, to reproduce and to survive. On this cycle all life depends.
    It is fairly well known that wild animals survive from year to year by eating as much as they can during times of plenty, the summer and fall, storing the excess, usually in the form of fat, and then using these reserves of fat to survive during the hard times in winter when food is scarce. But it is probably less well known that even with their stored fat, wild animals spend less energy to live in winter than in summer.
    A good case in point is the whiter-tailed deer. Like most wildlife, deer reproduce, grow, and store fat in the summer and fall when there is plenty of nutritious food available. A physically mature female deer in good condition who has conceived in November and given birth to two fawns during the end of May or first part of June, must search for food for the necessary energy not only to meet her body\'s needs but also to produce milk for her fawns. The best milk production occurs at the same time that new plant growth is available. This is good timing, because milk production is an energy consuming process — it requires a lot of food. The cost can not be met unless the region has ample food resources.
    As the summer progresses and the fawns grow, they become less dependent on their mother\'s milk and more dependent on growing plants as food sources. The adult males spend the summer growing antlers and getting fat. Both males and females continue to eat high quality food in the fall in order to deposit body fat for the winter. In the case of does and fawns, a great deal of energy is expended either in milk production or in growing, and fat is not accumulated as quickly as it is in full grown males. Fat reserves are like bank accounts to be drawn on in the winter when food supplies are limited and sometimes difficult to reach because of deep snow.
    As fall turns into winter, other changes take place. Fawns lose their spotted coat. Hair on all the deer becomes darker and thicker. The change in the hair coats is usually complete by September and maximum hair depths are reached by November or December when the weather becomes cold.
    But in addition, nature provides a further safeguard to help deer survive the winter—an internal physiological response which lowers their metabolism, or rate of bodily functioning, and hence slows down their expenditure of energy. The deer become somewhat slow and drowsy. The heart rate drops. Animals that hibernate practice energy conservation to a greater extreme than deer do. Although deer don\'t hibernate, they do the same thing with their seasonal rhythms in metabolism. Deer spend more energy and store fat in the summer and fall when food is abundant, and spend less energy and use stored fat in the winter when food is less available.
    When the \"energy crisis\" first came in 1973-1974, I was living with my family in a cabin on the edge of an area where deer spend the winter in northern Minnesota, observing the deer as their behavior changed from more activity in summer and fall to less as winter progressed, followed by an increase again in the spring as the snow melted. It was interesting and rather amusing to listen to the advice given on the radio: \" Drive only when necessary,\" we were told. \"Put on more clothes to stay warm, and turn the thermostat on your furnace down.\" Meanwhile we watched the deer reduce their activity, grow a winter coat of hair, and reduce their metabolism as they have for thousands of years. It is biologically reasonable for deer to reduce their cost of living to increase their chance of surviving in winter.
    Not every winter is critical for deer of course. If the winter has light snow, survival and productivity next spring will be high. But if deep snows come and the weather remains cold for several weeks, then the deer must spend more energy to move about, food will be harder to find, and they must then depend more on their fat reserves to pull them through. If such conditions go on for too long some will die, and only the largest and strongest are likely to survive. That is a fundamental rule of life for wild, free wandering animal such as deer.
    Yes, life—and death, too -- is a cycle that goes round and round, and when animals die their bodies become food for other life forms to use by converting them into energy.
    And the cycle continues.

New Words

Deer
n.  (sing. or pl.)鹿

    romantic
a.  belonging to or suggesting romance; fanciful not practical 浪漫的；幻想的

    turn
n.   a natural tendency; inclination(天生）倾向

    currency
n.  money that is actually in use in a country 通货，货币

    ecological
a.  of or concerning interrelationship of organisms and their environment 生态的

    ecology
n.  生态学
 
    convert
vt. change (from one form, use, etc. into another); cause (a person) to change his beliefs, etc. 使转变；使改变信仰（等）
  
    excess
n.  the part that is more than enough; the condition of exceeding what is usual or necessary 过量；过度
 
    reserve
n.  sth. that is being or has been stored for later use 储备（物）

    scarce a.  not available in sufficient quantity 缺乏的
  
    wildlife
n.  animals and plants which live and grow wild

    nutritious
a.  full grown and developed 成熟的；成年的

    female
a.  of the sex that gives birth to young  女（性）的；雌的
n.  a female person, animal or plant

    conceive
vt. become pregnant with (young); form (an idea, plan, etc.) in the mind 怀（胎）；构思

    fawn
n.  a young deer less than a year old
   
    timing
n.  selection for maximum effect of the precise moment for beginning or doing sth. 时机的选择

    consume
vt. eat or drink; use; use up 消耗；消费

    region
n.  a place, space or area; a part of the body 地区；（身体的）部位

    ample
a.  plentiful 充裕的
 
    resource
n.  (pl.) possessions (esp. of a country). in the form of wealth and goods, that help one to do what one wants 资源

    dependent
a. relying (on another) for support

    male
a.  of the sex that does not give birth to young 男（性）的；雄的
n.  a male person, animal or plant

    antler
n.  the solid, bony horn of a male deer 鹿角，茸角

    deposit
vt. put or store for safe keeping; (esp. of a liquid, a river) leave lying (a layer of matter)存放；使沉积

    doe
n.  a fully-grown female deer

    expend
vt. spend or use up 花费；耗尽

    accumulate
v.  make or become greater in number or quantity; collect or gather 积累；积聚

    account
n.  a sum of money kept in a bank which may be added to or taken from 帐户；存款

    spotted
a.  marked with spots

    depth
n.  the state or degree of being deep 深；深度，厚度

    safeguard
n.  a means of protection against sth. unwanted 预防措施

    internal
a.  of or in the inside, esp. of the body 内部的；体内的

    physiological
a.  生理的；生理学的

    metabolism
n.  新陈代谢

    hence
ad. therefore 因此，所以

    expenditure
n.  expending or using up; the amount of money, time, etc. expended 花费；用光；支出额，费用

    somewhat
ad. by some degree or amount; a little 有点，稍微

    drowsy
a.  sleepy or half sleepy; making one sleepy 困倦的；催眠的

    hibernate
vi. (of some animals) pass the whole of the winter in a state like sleep 冬眠

    extreme
n.  either end of anything; highest degree 极端

    seasonal
a.  depending on the season; changing with the seasons 季节性的

    rhythm
n.  节奏

    abundant
a.  more than enough 充足的；丰富的

    cabin
n.  a small roughly built, usu. wooden house 小木屋；茅舍

    melt
v.  cause (a solid) to become liquid; (of a solid ) become liquid （使）融化；（使）熔化

    amusing
a.  funny 逗人笑的；引起乐趣的
 
    amuse
vt. cause to laugh or smile

    thermostat
n.  an automatic device for regulating temperature 恒温器

    biologically
ad. 生物学上

    biological  a.

    survival
n.  the fact or likelihood of surviving 幸存

    productivity
n.  the ability or capacity to produce, productiveness 生产力；生产率；多产

    fundamental
a.  basic; most important

Phrases & Expressions

  go round  
  function smoothly
  
  in the form of
  以…形式

  in point
  appropriate; pertinent 适用的；相关的

  in (good) condition
  in good health, physically fit

  give birth (to)
  bear; (fig.) produce 生（孩）子，产（仔）；产生，引起

  draw on
  take or use as a source 利用；动用

  slow down
  (cause to ) go more slowly than usual; (cause to ) live, work, etc. in a less active and intense way （使

）慢下来；（使）放松

  turn down
  reduce the force, speed, loudness, etc. of (sth.) by using controls 减弱；关小，调低

  move about
  travel around; go from one place to another

  pull through
  help (sb.) to survive a period of danger or crisis 使渡过危险或危机

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