2022年9月六级 第1套 Section A 选词填空

The now extinct passenger pigeon has the dubious honor of being the last species anyone ever expected to disappear. At one point, there were more passenger pigeons than any other species of bird. Rough __26__ of their population went as high as five billion and they accounted for around 40 percent of the total indigenous bird population of North America in the early 19th century.

Despite their huge population, passenger pigeons were __27__ to human intrusion into their nesting territory. Their nests were shabby things and two weeks after the eggs __28__, the parent pigeons would abandon their offspring, leaving them to take care of themselves. People discovered that these baby pigeons were really tasty, and the adult birds were also quite __29__. First the Native Americans and then the transplanted Europeans came to consider the birds a great __30__.

By the 1850s, commercial trapping of passenger pigeons was proceeding at an __31__ pace. Hundreds of thousands of the birds were being harvested every day to be made into popular pigeon pies. In addition, large __32__ of the pigeons' nesting territory were being cleared away for planting crops and creating pasture land. As numerous as the passenger pigeons were, they were not an __33__ resource. By the 1880s, it was noticed that the bird population had become seriously __34__. The last passenger pigeons killed in the wild were shot in 1899.

Eventually those billions and billions of birds shrank to a single remaining __35__, a passenger pigeon named Martha, who died on September 1, 1914, in captivity at the Cincinnati Zoo. In addition to being the end of an era, it was also the first time humans were able to exactly time the extinction of a species.