PrepTest 77, Section 2, Question 4
The northern cardinal, a nonmigratory songbird, was rare in Nova Scotia in 1980; the province was considered to be beyond that bird's usual northern range. By 2000, however, field observations indicated that northern cardinals were quite common there. The average winter temperature rose slightly over that period, so warmer winters are probably responsible for the northern cardinal's proliferation in Nova Scotia.
The northern cardinal, a nonmigratory songbird, was rare in Nova Scotia in 1980; the province was considered to be beyond that bird's usual northern range. By 2000, however, field observations indicated that northern cardinals were quite common there. The average winter temperature rose slightly over that period, so warmer winters are probably responsible for the northern cardinal's proliferation in Nova Scotia.
The northern cardinal, a nonmigratory songbird, was rare in Nova Scotia in 1980; the province was considered to be beyond that bird's usual northern range. By 2000, however, field observations indicated that northern cardinals were quite common there. The average winter temperature rose slightly over that period, so warmer winters are probably responsible for the northern cardinal's proliferation in Nova Scotia.
The northern cardinal, a nonmigratory songbird, was rare in Nova Scotia in 1980; the province was considered to be beyond that bird's usual northern range. By 2000, however, field observations indicated that northern cardinals were quite common there. The average winter temperature rose slightly over that period, so warmer winters are probably responsible for the northern cardinal's proliferation in Nova Scotia.
Which one of the following, if true, most weakens the argument?
Bird feeders, an important source of nutrition to wintering birds, became far more common in Nova Scotia after 1980.
Because of their red plumage, northern cardinals are easier to spot than most other songbird species are.
Some songbird species other than the northern cardinal also became more common between 1980 and 2000.
According to field observations, the populations of migratory birds fluctuated less during the period from 1980 to 2000 than the populations of nonmigratory birds.
Birds that prey on songbirds became more common in Nova Scotia between 1980 and 2000.
Explanations
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