11.7

1. 1. Listen to Track 95.

      Now answer the questions.

   1. What does the professor mainly talk about?

      1. Changes in the migration patterns of chimney swifts
      2. Causes of the decline in chimney swift populations
      3. Where chimney swifts nest in rainforests
      4. Health risks of residential pesticides

   2. What does the professor imply might be causing a decline in the chimney swift population?

      1. Deforestation along their migration routes
      2. An increase in hunting activity
      3. A decrease in the number of homes with uncapped or unsealed chimneys
      4. A change in the birds’ migration patterns

   3. What does the professor say about how the use of pesticides affects chimney swift populations?

      1. Pesticides are poisoning chimney swift populations.
      2. Pesticides are an effective way to reduce parasites that are harmful to chimney swifts.
      3. Pesticides have little or no impact on chimney swift populations.
      4. Pesticides kill the primary food sources of chimney swifts, making food harder to find.

   4. According to the professor, how are some scientists estimating the decline in the chimney swift population?

      1. Counting the swifts that return to suitable nests each year
      2. Collecting estimates from people who report seeing a chimney swift nest
      3. Tracking the birds with radio-frequency identification tags
      4. Constructing swift “towers” to attract the birds

   5. What does the professor imply about bird perching?

      1. Most birds only perch in a nest.
      2. A bird is more vulnerable to attack when perched.
      3. Perching is essential for migrating chimney swifts.
      4. The majority of birds can perch.

2. 1. Listen to Track 96.

      Now answer the question.

   6. What does the professor imply when she says this?

      1. She does not think her next point is important enough to share.
      2. Students are likely to find her next point obvious.
      3. She is unsure about her next point.
      4. She believes the next point will confuse students.