Each spring, nature lovers eagerly greet the signs that winter is finally coming to an end.
每年春天，爱好大自然的人们渴望见到冬天终于结束的征兆。
As the days grow warmer, the flowers and trees start to bloom,
随着天气逐渐暖和，花朵和树木开始萌芽，
and the world comes alive with the melodious call of birds in search of a new mate.
世界开始生气勃勃，悦耳动人的小鸟开始鸣唱，寻找着新伴侣。
But where have these enchanting sounds been hiding all winter?
但是这些动人的歌声在冬天时躲到哪里去了？
For almost 200 species of song birds, their winters have been spent down in the tropical climates of Central and South America.
近200种鸣鸟在冬天时飞往位于热带气候区的中南美洲。
While this may sound ideal, it involves one of the most perilous journeys known in the entire animal kingdom.
这听起来可能不切实际，因为这在整个动物王国中是一段非常危险的旅程。
This journey is called migration, and for song birds,
这趟旅程称为迁徒，而对鸣鸟来说
this can involve travelling somewhere between a few hundred to almost 7,000 miles in a period of several weeks to four months.
这可能意味着要飞行几百英里到近七千英里的距离，长达数周到四个月之久。
Birds spend weeks preparing for the intense journey by gorging on large quantities of food,
鸟儿为准备这趟艰辛的旅程，会花费数周时间吞下极大量的食物，
sometimes doubling their weight prior to departure.
有时在出发前要让体重加倍。
While flying, birds can lose almost one percent of their body weight an hour,
在飞行时，鸟类几乎每小时可以消耗1%的体重，
so packing on the pounds is crucial to their survival.
因此增重对它们是否能存活十分关键。
However, more than the physical stress, migrating birds are now facing a new source of hardship: landscape change.
然而，比身体压力更困难的是，鸟类迁徒正面临着一种新的困境：景观变化。
Just imagine you're the one getting ready to take a trip.
想象一下你是准备去旅行的人。
You've packed the car with everything you think you need, fueled up the tank, eaten a huge breakfast, and hit the road.
你把所有可能需要的东西放上车，加了油，吃了超大份早餐，然后上路去。
You've taken this journey before. You know all your favorite rest stops and little back-alley diners to grab a bite.
你以前走过这趟路。你知道你最爱的歇脚处，还有可以吃上一顿的独家晚餐。
Everything is planned out. But just as your fuel gauge starts dipping into the red zone,
所有的事都计划好了。但是当你的油表开始掉到红线区，
you pass by what should have been a gas station, except it's closed.
你经过了印象中该有的那间加油站，可是它早就关了。
'Not a problem,' you think, 'The next one can't be too far away.'
你想：没问题。下一间不会太远。
But then that next station never appears.
但是下一间加油站永远都没出现。
Unfortunately, as you continue on your route, the reality of the situation starts to set in.
不幸的是，当你继续走的时候，现实的情况开始上演。
More and more stations are closed or just erased from your map.
越来越多的加油站关门，或是消失在你的地图上。

All of a sudden, your routine trip has become a desperate search just to find somewhere safe to rest and refuel for the night.
突然之间，你的旅程变成紧急搜寻，只为了找到一个安全的地方休息、加油和过夜。
This scenario has become the reality for the majority of migrating song birds as human land development continues unchecked.
当人类无止境地开发土地之际，这个场景成为了大多数鸣鸟的现实情节。
Humans are altering important stop-over sites that birds have been using for generations.
人类改变了鸟类使用了好几个世代的重要的中继站。
As migrators pass over the continent, they run a gauntlet of dangers,
当候鸟飞越大陆，它们冒着生命危险，
including pesticide ingestion in rural farmlands,
包含了吸入乡间农园里的农药，
habitat loss in suburban developments, as well as disorientation from light pollution,
郊区开发使得栖息地丧失，还有在光污染中迷失方向，
and even structure collision with tall, reflective glass buildings in cities.
甚至是撞上城市中又高又闪亮的玻璃高楼。
Of the estimated 20 billion individual birds that comprise the fall population,
秋天时，鸟类总数大约有200亿只左右，
only about half will return to breed the following spring.
但是只有一半的鸟会回来迎接下一个春天。
Almost one billion of these deaths are attributed just to building collisions.
几乎有10亿只鸟类因为撞上大楼而死亡。
With such astounding yearly losses, humans risk more than just the loss of the beautiful colors and songs of birds,
随着每年如此惊人的损失，人类冒的险不只是失去了鸟类美丽的色彩和歌声，
they also play an important role in the ecosystem.
它们在生态中也占了极重要的地位。
Birds help with insect control, pollination, and disbursing seeds throughout the landscape.
鸟类帮助控制昆虫，植物授粉，还有在各地播下种子。
Without birds, the natural world would be a very different place.
没有了鸟类，大自然会变得非常不一样。
Although birds face an on-going threat from human land development, there are actions that we can all take to help.
虽然鸟类持续面临人类土地开发的威胁，但还有一些我们帮得上忙的行动。
Many countries and local governements have already passed important laws that restrict the use of poisonous pesticides.
许多国家和地方政府已经通过重要的法令限制有毒的农药。
By using more natural, plant-based products, we can maintain our farms and gardens without the dangerous side effects.
通过使用自然、植物制品，我们可以维护农场和花园，又不会有危险的副作用。
In addition, as our global populations continue to grow and people need places to call home,
此外，当全球人数持续增加，人们都需要一个称为家的地方，
green spaces can offer both bird habitat as well as a peaceful and natural place for us to enjoy.
绿地能够提供鸟类栖息，同样也能成为一个安宁的自然环境，让我们享受其间。
Small changes at home can also make a huge difference.
在家里做小小的改变也能带来大大的不同。
By hanging up feeders and building bird houses in outdoor areas,
你可以挂上喂食箱，为鸟类在户外盖一个家，
we can provide much-needed food and safety during long migrations.
我们能够在长期的迁徒途中提供足够的食物和安全。
Turning out lights in suburban and urban environments can also help birds that look for stars to navigate.
关上郊区和城市的路灯，也能帮助鸟类找到指引方向的星星。
With our help, these sky travellers can reach their destination safely, and hopefully keep returning year after year.
通过我们的帮助，这些天空中的旅行家能够安全地抵达目的地，但愿它们每一年都能回来。