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55. Read the following passage.
The red squirrel is not as common in Britain as it was a
century ago. The grey squirrel, introduced from North
America, is now extremely common. One suggestion for the
relative success of the grey squirrel is that it is able to out-
compete the smaller red squirrel in areas where they both
occur.
Detailed studies have shown that the two species have lived
together in some areas for up to 16 years whereas in other
areas the red squirrels had disappeared before the grey
squirrels arrived.
Red squirrels do better in coniferous woodland where, being lighter and more agile, they
are able to exploit the abundant cones in the canopy of the trees. The cones provide the
red squirrels with seeds as a source of food throughout the year. Grey squirrels feed
mainly on fruits and seeds such as acorns found on the ground in broad-leaved woodland.
Grey squirrels can digest acorns more efficiently than can red squirrels. Red squirrels do
eat acorns but lose mass when given a diet consisting only of acorns.
,(a) Give two pieces of evidence from the passage which suggest that the reduction in
red squirrel numbers is not simply due to competition with grey squirrels.
, (c) Surveys have shown that, following a prolonged winter, red squirrels tend to
disappear from broad-leaved woodland where both species have previously lived
together.
Suggest why the red squirrels disappear.
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