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2013年
06月10日
10:14 bbbcさん

TED-Ed 026・・Bird migration, a perilous journey        (渡り鳥の危険な旅について)

  • 英語の話題
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易しいが日本人には早い。母国ではこれでも遅めなので同時読みの練習向き。     
    
04分・・175wpm   2013/11/11 新出

字幕:上の動画は開始後 で字幕On/Off。 で言語選択、文字サイズはオプションから。

下記英文はマウスオーバー辞書が使えます。            

Each spring, nature lovers eagerly greet the signs that winter is finally coming to an end. As the days grow warmer, the flowers and trees start to bloom, and the world comes alive with the melodious call of birds in search of a new mate. But where have these enchanting sounds been hiding all winter?

For almost 200 species of song birds, their winters have been spent down in the tropical climates of Central and South America. While this may sound ideal, it involves one of the most perilous journeys known in the entire animal kingdom. This journey is called migration, and for song birds, this can involve travelling somewhere between a few hundred to almost 7,000 miles in a period of several weeks to four months.

Birds spend weeks preparing for the intense journey by gorging on large quantities of food, sometimes doubling their weight prior to departure. While flying, birds can lose almost one percent of their body weight an hour, so packing on the pounds is crucial to their survival. However, more than the physical stress, migrating birds are now facing a new source of hardship: landscape change.

Just
imagine you're the one getting ready to take a trip. You've packed the car with everything you think you need, fueled up the tank, eaten a huge breakfast, and hit the road. You've taken this journey before. You know all your favorite rest stops and little back-alley diners to grab a bite. Everything is planned out(綿密に計画する).

But just as your fuel gauge starts dipping into the red zone, you pass by what should have been a gas station, except it's closed. "Not a problem," you think, "The next one can't be too far away. But then that next station never appears. Unfortunately, as you continue on your route, the reality of the situation starts to set in. More and more stations are closed or just erased from your map.

All
of a sudden, your routine trip has become a desperate search just to find somewhere safe to rest and refuel for the night. This scenario has become the reality for the majority of migrating song birds as human land development continues unchecked. Humans are altering important stop-over sites that birds have been using for generations.

As migrators pass over the continent, they run a gauntlet of dangers, including pesticide ingestion in rural farmlands, habitat loss in suburban developments, as well as disorientation from light pollution, and even structure collision with tall, reflective glass buildings in cities. Of the estimated 20 billion individual birds that comprise the fall population, only about half will return to breed the following spring. Almost one billion of these deaths are attributed just to building collisions.

With such astounding yearly losses, humans risk more than just the loss of the beautiful colors and songs of birds, they also play an important role in the ecosystem. Birds help with insect control, pollination, and disbursing seeds throughout the landscape. Without birds, the natural world would be a very different place.

Although birds face an on-going threat from human land development, there are actions that we can all take to help. Many countries and local governements have already passed important laws that restrict the use of poisonous pesticides. By using more natural, plant-based products, we can maintain our farms and gardens without the dangerous side effects.

In addition, as our global populations continue to grow and people need places to call home, green spaces can offer both bird habitat as well as a peaceful and natural place for us to enjoy. Small changes at home can also make a huge difference. By hanging up feeders and building bird houses in outdoor areas, we can provide much-needed food and safety during long migrations. Turning out lights in suburban and urban environments can also help birds that look for stars to navigate. With our help, these sky travellers can reach their destination safely, and hopefully keep returning year after year.
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