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PASSAGE 11

Read the folloning passage and mark the letter A, B, C, or D on your answer sheet to indicate the

correct answer to each of the questions.

Birds that feet in flocks commonly retire together into roosts. The reasons for roosting communally are

not always obvious, but there are some likely benefits. In winter especially, it is important for birds to

keep warm at night and conserve precious food reserves. One way to do this is to find a sheltered, roost.

Solitary roosters shelter indense vegetation or enter a cavity - horned larks dig holes in the ground and

ptarmigan burrow into snow banks - but the effect of sheltering is magnified by several birds huddling

together in the roosts, as wrens, swifts, brown creepers, bluebirds, and anis do. Body contact reduces the

surface area exposed to the cold air, so the birds keep each other warm. Two kinglets huddling together

were found to reduce their heat losses by a quarter, and three together saved a third of their heat.

The second possible benefit of communal roosts is that they act as "information centers”. During the day,

parties of birds will have spread out to feed over a very large area. When they return in the evening some

will have fed well, but others may have found little to eat. Some investigators have observed that when

the birds set out again next morning, those birds that did not feed well on the previous day appear to

follow those that did. The behavior of common and lesser kestrels may illustrate different

feeding

behaviors of similar birds with different roosting habits. The common kestrel hunts vertebrate animals in

a small, familiar hunting ground, whereas the very similar lesser kestrel feeds on insects over a large area.

The common kestrel roosts and hunts alone, but the lesser kestrel roosts and hunts in flocks, possibly so

one bird can learn from others where to find insect swarms.

Finally, there is safety in numbers at communal roosts since there will always be a few birds awake at any

given moment to give the alarm. But this increased protection is partially counteracted by the fact that

mass roosts attract predators and are especially vulnerable if they are on the ground. Even those in trees

can be attacked by birds of prey. The birds on the edge are at greatest risk since predators find it easier to

catch small birds perching at the margins of the roost.

Question 1. What does the passage mainly discuss?

A. How birds find and store food

B. How birds maintain body heat in the winter

C. Why birds need to establish territory

D. Why some species of birds nest together

Question 2. The word "conserve" is closest in meaning to

.

A. retain

B. watch

C. locate

D. share

Question 3. Ptarmigan keep warm in the winter by

.

A. building nests in trees

B. huddling together on the ground with other birds

C. digging tunnels into the snow

D. burrowing into dense patches of vegetatiotnir

Question 4. The word "magnified" in line 6 is closest in meaning to

.

A. combined

B. caused

C. modified

D. intensified

Question 5. The author mentions kinglets in line 9 as an example of birds that

.

A. nest together for warmth

B. usually feed and nest in pairs

C. protect themselves by nesting in holes

D. nest with other species of birds

Question 6. Which of the following statements about lesser and common kestrels is true?

A. The common kestrel nests in larger flocks than does the lesser kestrel.

B. The lesser kestrel and the common kestrel have similar diets.