Choose a word or sentence for each gap that best fits the text context.

THE Arctic tern, a black-crowned seabird weighing no more than a bar of soap, flies from the top of the world to the bottom and back again every year. That’s 40,000 kilometres as the crow flies. But when researchers equipped terns with satellite tracking devices, they discovered that 1. . One individual ended up covering close to 100,000 kilometres – equivalent to more than twice around the planet. Why bother to migrate? It’s not hard to see why migratory birds leave places such as northern Europe for warmer climes like central Africa as winter draws in: why struggle through colder temperatures, shorter days and scarcer food supplies when you can be somewhere with pleasant temperatures and plentiful food. But that raises another question: why do these birds risk their lives 2. ?Why not stay where it’s warm? One theory is that it comes down to 3. . “In the tropics, competition for nesting space is fierce,” says Anders Hedenström at Lund University in Sweden. “So it may well pay to opt out of that fight and fly north, where the food supply peaks in summer and there is more room for nesting – at least if you get there in time, because the best spots may get filled fairly rapidly.” Enlarge That might explain why many migratory birds are in such a hurry during their spring migration. Some common swifts flying across the Mediterranean and the Sahara Desert took more than two months to complete the southern journey in autumn, while 4. . Then again, in terms of the 5. of intercontinental migration, it’s far from clear that all birds making these journeys today started out travelling north from the tropics during the summer. In 2014, Ben Winger at the University of Michigan and his colleagues built a mathematical model to 6. the geographical ranges of the ancestors of hundreds of living species of American songbird. They found that most long-distance migrants began in the north and started flying south for winter, as opposed to being tropical birds flying north for summer. All of which still leaves open the question of why some species 7. . Why not find somewhere closer for a winter escape? We’re still a world away from a conclusive answer. One idea is that favourable winter-summer habitats 8. as a result of the movement of continents, forcing birds to cover just a few extra millimetres each year – but vast distances millions of years later.
12.1 But when researchers equipped terns with satellite tracking devices, they discovered that _________.

Question

Choose a word or sentence for each gap that best fits the text context. 
 
  THE Arctic tern, a black-crowned seabird weighing no more than a bar of soap, flies from the top of the world to the bottom and back again every year. That’s 40,000 kilometres as the crow flies. But when researchers equipped terns with satellite tracking devices, they discovered that   1.  . One individual ended up covering close to 100,000 kilometres – equivalent to more than twice around the planet. Why bother to migrate?  It’s not hard to see why migratory birds leave places such as northern Europe for warmer climes like central Africa as winter draws in: why struggle through colder temperatures, shorter days and scarcer food supplies when you can be somewhere with pleasant temperatures and plentiful food. But that raises another question: why do these birds risk their lives  2. ?Why not stay where it’s warm?  One theory is that it comes down to  3. . “In the tropics, competition for nesting space is fierce,” says Anders Hedenström at Lund University in Sweden. “So it may well pay to opt out of that fight and fly north, where the food supply peaks in summer and there is more room for nesting – at least if you get there in time, because the best spots may get filled fairly rapidly.” Enlarge  That might explain why many migratory birds are in such a hurry during their spring migration. Some common swifts flying across the Mediterranean and the Sahara Desert took more than two months to complete the southern journey in autumn, while  4. . Then again, in terms of the  5.  of intercontinental migration, it’s far from clear that all birds making these journeys today started out travelling north from the tropics during the summer. In 2014, Ben Winger at the University of Michigan and his colleagues built a mathematical model to  6.  the geographical ranges of the ancestors of hundreds of living species of American songbird. They found that most long-distance migrants began in the north and started flying south for winter, as opposed to being tropical birds flying north for summer. All of which still leaves open the question of why some species  7. . Why not find somewhere closer for a winter escape? We’re still a world away from a conclusive answer. One idea is that favourable winter-summer habitats  8.  as a result of the movement of continents, forcing birds to cover just a few extra millimetres each year – but vast distances millions of years later. 
  12.1 But when researchers equipped terns with satellite tracking devices, they discovered that _________.

Accepted Answer

these birds do not take the shortest path

Answer

surprisingly few birds could cover the distance

Answer

the devices on many birds did not work

Crowdly

Choose a word or sentence for each gap that best fits the text context. THE...

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