How have mammals and birds with large territories been affected by habitat fragmentation?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Their populations have declined.
Habitat loss and fragmentation is a main cause of the loss of biodiversity. When human activities break a large habitat into small fragments, animals that need large territories, and animals with migratory habits, can no longer find enough space and resources. Their populations decline.
Option (1) Their populations have increased. — Incorrect. Fragmentation takes away the space these animals need. Their numbers fall; they do not rise.
Option (2) Their migratory habits have changed. — Incorrect. The book says animals with migratory habits are badly affected, which leads to population declines. It does not say that their habits change.
Option (3) Their populations have declined. — Correct. Mammals and birds that need large territories are badly affected, and their populations go down.
Option (4) Their territories have expanded. — Incorrect. The habitat is broken into small fragments, so there is less room, not more. Their territories cannot expand.
NCERT Extract:
Loss of Biodiversity – “… Besides total loss, the degradation of many habitats by pollution also threatens the survival of many species. When large habitats are broken up into small fragments due to various human activities, mammals and birds requiring large territories and certain animals with migratory habits are badly affected, leading to population declines.”