With reference to the environment, the Birds are considered to be excellent indicator species. What is / are reasons for this?
1. Birds live in every climate and biome.
2. Birds respond quickly to environmental change
3. Birds are relatively easy to track and count
Choose the correct option from the codes given below:

Answer: [D] 1, 2 & 3

This question is a part of GKToday's Integrated IAS General Studies Module