Question

Many different species of songbirds migrate into the United States and Canada from Central and South America each summer in order to take advantage of the caterpillars and other insects that hatch in the northern forests during the summer. Over the past several decades songbird populations have been declining. How might a decrease in the number of songbirds be expected to affect the trees in a northern forest?

A. The trees would not be affected if there were fewer songbirds since the birds only eat insects and would not be feeding off the trees.
B. The trees would stop growing if herbivorous insects damaged their leaves at all, so there would be very little new growth in the forests.
C. The trees would suffer more leaf damage as herbivorous insect populations increased until the populations of other insect predators increased in response.
D. The trees would produce more seed since fewer birds were there to eat, and more young trees would begin to grow up in the forests.

Answer 1

The answer is C. Since there are no song birds to eat the insects, the insects would be able to eat more leaves, at least until the insect predator population grew

Answer 2

Ans.

The songbirds that migrate to northern forests during summer, feed on insects and caterpillars that hatch in summer. Thus, songbirds are predators, while insects and caterpillars are preys. Therefore, a decrease in songbird population will result in increase in population of insects and caterpillars.

As insects and caterpillars feed on plant leaves, it will lead to more damage to the plant leaves due to herbivores insects until other insect predators will increase in that environment.

Thus, the correct answer is option C).