Andrew runs a car repair workshop in a village in London, where swallows have made their nests on the crossbeams beneath its roof. All day long, they fly in and out, bringing back insects for their hungry chicks, seemingly unconscious of the constant noise and the comings and goings of customers. However, this spring the swallows didn’t arrive back at his workshop until 10 April — the latest they have returned in nearly 40 years. Actually, the average return date has been 8 April, but this year I didn’t see one over my garden in Scottish Highlands until the 25th. Numbers are down, too. While the tide appears to have turned up from last weekend onwards, other familiar species, like house martin (毛脚燕), needle-tailed swift, etc have been very few and far between.
There are two reasons for their late arrival. Unlike many other migrating (迁徙) birds, which fatten themselves up before they depart, these species feed as they travel, replenishing (补充) lost energy by catching flying insects. For that reason, they are especially vulnerable to bad weather. And the weather in southern Europe this spring has been very unpredictable.
The second reason is that, here in Britain these years, although the weather has been mainly dry, there have been persistent easterly and northeasterly winds, which may have also slowed down the birds’ progress as they headed north.
How might this end up affecting these global travellers over the long term? Migrating birds usually live for only one or two years, so they need to get down to raising a family as soon as they return. Swallows, which usually start nesting in early April, may only be able to raise a single hatch this year, rather than two as they do in most years.
I have seen swallows all over the world and discovered just how important they are as a sign of spring: not just in Britain but all the way across the northern hemisphere. Yet I am concerned that rapid changes in the world’s climate pose a real threat to their chances of breeding successfully and their long-term future, even a week or two delays.
Fortunately, warm weather and clear skies have finally come to southern Europe, and the migration floodgates have opened. Earlier last week, down on the Somerset coast, I saw a steady passage of swallows, together with a few house martins, all heading steadily northwards. With warm sunshine and enough rain to produce quantities of insects, the swallows might be able to compensate for their lost time.
8. What can be inferred from the first three paragraphs?
A.Swallows’ migration is always as regular as clockwork. |
B.Swallows are attracted by the steady stream of visitors. |
C.Swallows love making their nests around human places. |
D.Swallows’ lateness for the spring becomes a universal trend. |
9. What does the author probably agree with?
A.Unsettled weather affects swallows’ feeding pattern. |
B.Abundant food supply makes up for swallows’ lost time. |
C.Persistent winds step up swallows’ progress towards south. |
D.There is an upward tendency in varieties of migrating birds. |
10. If climate problems continue to worsen, what might swallows suffer in the future?
A.A threat to their immune system. | B.A decrease in their life span. |
C.A decline in their population. | D.A slim chance of nesting for chicks. |
11. What’s the author’s writing purpose?
A.To raise great concerns about climate change. |
B.To introduce migration habits of different birds. |
C.To propose ideas for addressing global warming. |
D.To call for people to save the endangered species. |