在野生环境下，刚刚独立生活的雏鸟死亡率特别高。经过长期的进化，小鸟们找到了让雏鸟离开父母的最佳时机。
A compromise that makes songbirds survive
by George Dvorsky
Every bird you see outside your window is a survivor. In juvenile birds, for example, mortality rates during the first three weeks outside the nest range from 12 percent to an astounding（令人震惊的） 70 percent, depending on the species. Needless to say, baby birds need to leave their nests at the right stage of development to boost their chances of making it to adulthood.
survivor /səˈvaɪvə(r)/ n. 幸存者（由survive加上表示人的后缀-or）
juvenile /ˈdʒuːv(ə)naɪl/ adj. 未成年的
mortality /mɔːˈtæləti/ n. 死亡、死亡率
rate /reɪt/ n. 比率、速率
nest /nest/ n. 鸟窝、鸟巢
range /reɪndʒ/ v. （在某个范围内）变化
depend on 取决于
species /ˈspiːʃiːz/ n. 物种（单数和复数都是species）
needless /ˈniːdləs/ adj. 不需要的（由need加上表示否定的后缀-less并变成形容词）
stage /steɪdʒ/ n. 阶段
boost /buːst/ v. 提高、增加
make it 成功做到
adulthood /ˈædʌlthʊd/ n. 成年期
If a baby bird leaves the nest too early, when its wings aren't yet fully developed, it's at greater risk of being caught by predators. But the nest itself isn't always a safe space, as it's vulnerable to squirrels（松鼠）, chipmunks（花粟鼠） and snakes. Therefore, bird parents want to get their chicks out into the real world as fast as possible, since when a predator attacks a nest, it typically kills the entire brood（一窝雏鸟）.
risk /rɪsk/ n. 风险
predator /ˈpredətə(r)/ n. 捕食者
vulnerable /ˈvʌln(ə)rəb(ə)l/ adj. 易受伤害的、易受攻击的
chick /tʃɪk/ n. 雏鸟
entire /ɪnˈtaɪə(r)/ adj. 整个的、全部的
As new research suggests, the tension that arises between baby birds who don't want to leave the nest and parents who would very much like them out ultimately results in an ideal departure time that boosts survival rates.
suggest /səˈdʒest/ v. 表明
tension /ˈtenʃ(ə)n/ n. 紧张局势、紧张关系
arise /əˈraɪz/ v. 发生
ultimately /ˈʌltɪmətli/ adv. 最终
result in 造成、导致
ideal /aɪˈdɪəl/ adj. 理想的
departure /dɪˈpɑːtʃə(r)/ n. 离开
survival /səˈvaɪv(ə)l/ n. 生存（由survive加后缀-al变成名词）
For the study, researchers from University of Montana examined the flight performance of eleven different species of songbirds. They were looking at the birds' ability to slow their descent, or fly in a sustainable manner. Other factors, such as the age of the birds at first departure and variations in wing growth rates, were also taken into account.
researcher /rɪˈsɜːtʃə(r)/ n. 研究者（由research加上表示人的后缀-er）
examine /ɪɡˈzæmɪn/ v. 仔细考查
performance /pəˈfɔːməns/ n. 表现、性能
songbird /ˈsɒŋbɜːd/ n. 鸣叫像唱歌的鸟（由song和bird组成）
descent /dɪˈsent/ n. 下降
sustainable /səˈsteɪnəb(ə)l/ adj. 可持续的（由sustain加后缀-able变成形容词）
manner /ˈmænə(r)/ n. 方式
factor /ˈfæktə(r)/ n. 因素
variation /ˌveərɪˈeɪʃ(ə)n/ n. （数量、水平等）变化
growth /ɡrəʊθ/ n. 生长
take into account 考虑到、考虑进来
Radio transmitters were placed on eight species of the songbirds to see if they were still alive seven days after leaving the nest. The researchers also studied the rate at which baby birds were killed in the nest, in order to determine if birds were leaving at an optimal time.
transmitter /trænzˈmɪtə(r)/ n. 发射机（由transmit加上表示人或物的后缀-er）
place /pleɪs/ v. 放置
alive /əˈlaɪv/ adj. 活着的
determine /dɪˈtɜːmɪn/ v. 查明
optimal /ˈɒptɪməl/ adj. 最优的
The results were not entirely surprising. The poorer the flight performance exhibited by a bird, the greater chance it had of being killed by a predator. What's more, the data also showed that the push-and-pull between nestlings（还不会飞的雏鸟） and their parents resulted in an optimal departure time that minimized mortality.
entirely /ɪnˈtaɪəli/ adv. 完全地（由entire加后缀-ly变成副词）
poor /pʊə(r)/ adj. 差的、不好的
exhibit /ɪɡˈzɪbɪt/ v. 展现、显现
data /ˈdeɪtə/ n. 数据
minimize /ˈmɪnɪmaɪz/ v. 最小化、使最小
"Offspring leave the nest at an age that is later than optimal from the parents' perspective and earlier than optimal from an offspring's perspective, yielding a compromise between parents and offspring that balances risk of mortality in versus out of the nest," write the researchers in the study.
offspring /ˈɒfsprɪŋ/ n. 子女（单数和复数都是offspring）
perspective /pəˈspektɪv/ n. （看问题的）角度
yield /jiːld/ v. 产出、产生
compromise /ˈkɒmprəmaɪz/ n. 折中、各让一步
balance /ˈbæl(ə)ns/ v. 平衡、使平衡
versus /ˈvɜːsəs/ prep. 对、与…相对（常缩写为vs）
Natural selection doesn't care how a solution is reached – if a survival strategy works, it will get passed down. In this case, irritated parents dealing with unhappy youngsters produces a result that's beneficial for the species as a whole.
selection /sɪˈlekʃ(ə)n/ n. 选择（由select加后缀-ion变成名词）
strategy /ˈstrætədʒi/ n. 策略
pass down 传给下一代
irritate /ˈɪrɪteɪt/ v. 使烦恼、使不悦
deal with 应对、对付
youngster /ˈjʌŋstə(r)/ n. 青少年
beneficial /ˌbenɪˈfɪʃ(ə)l/ adj. 有益的
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