In an area where DDT had been used extensively, the population of birds declined significantly because:

Correct answer: D. Many of the birds eggs laid, did not hatch.

  • A. Birds stopped laying eggs.
  • B. Earthworms in the area got eradicated.
  • C. Cobras were feeding exclusively on birds.
  • D. Many of the birds eggs laid, did not hatch.

Explanation

Higher amounts of DDT disturb calcium metabolism of birds resulting in thinning of egg shells and their premature breaking that kills the embryos. Thus many of the eggs laid by birds did not hatch.

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