BBC媒体英语：世界野生鸟类总数超过500亿只 More than 50 billion wild birds in the world

据最新估计，世界上至少有 500 亿只野生鸟类。
 
Counting the number of wild birds in the world is no easy task. Scientists turned to a database, known as eBird, where birdwatchers record sightings of everything from woodpeckers to herons, to ospreys.
统计世界野生鸟类的总数并非易事。科学家们求助于一个名为 “eBird” 的数据库，观鸟者在数据库记录下观察到的啄木鸟、鹭、鹗等鸟类的信息。
 
The researchers came up with an estimate of 50 billion individual wild birds currently living on the planet. That's about six birds for every human being.
研究人员们估计，目前生活在地球上的野生鸟类有500亿只，相当于地球人口的六倍左右。
 
The house sparrow tops the charts, followed closely by the European starling, the ring-billed gull, and the barn swallow.
其中，家麻雀数量位居榜首，紧随其后的是欧椋鸟、环嘴鸥和家燕。
 
词汇表
task 差事，任务
birdwatchers 观鸟者
woodpeckers 啄木鸟
herons 鹭
ospreys 鹗，鱼鹰
came up with 得出了
starling 椋鸟
gull 海鸥
swallow 燕子
 
阅读理解：请在读完上文后，回答下列问题。
1. Who are the people that record sightings of birds in the eBird database?
2. True or false? The study includes all birds on the planet.
3. How many wild birds are there for each human?
4. Which wild bird is the most common, according to the study?
 
答案  
1. Who are the people that record sightings of birds in the eBird database?
Birdwatchers record sightings in the database.
2. True or false? The study includes all birds on the planet.
False. It only includes wild birds, and not those in captivity.
3. How many wild birds are there for each human?
There are around six wild birds for every human.
4. Which wild bird is the most common, according to the study?
The house sparrow tops the charts.