UPSC Prelims 2014 Q20: Environment & Ecology – Ecosystems & Ecology Concepts
If you walk through countryside, you are likely to see some birds stalking alongside the
cattle to seize the insects disturbed by their movement through grasses. Which of the following
is/are such bird/birds?
1. Painted Stork
2. Common Myna
3. Black - necked Crane
Select the correct answer
using the code given below.
- (a) 1 and 2
- (b) 2 only
- (c) 2 and 3
- (d) 3 only
Answer: (b) 2 only
Explanation
Birds that follow cattle for insects
| Bird | Stalks alongside cattle? | Habit |
|---|---|---|
| 1. Painted Stork | No | A wetland bird; wades in shallow water and eats fish |
| 2. Common Myna | Yes | Feeds on insects disturbed by grazing cattle |
| 3. Black-necked Crane | No | Lives in high-altitude wetlands of Ladakh and Arunachal Pradesh |
The relationship:
| Term | Meaning |
|---|---|
| Commensalism | One gains, the other is neither helped nor harmed |
| Example | Cattle egret and myna feeding near cattle |
The cattle egret is the best-known bird of this kind.
The black-necked crane is the state bird of Ladakh and is sacred to Buddhists.
Answer: (b) 2 only.
Why each option is right or wrong
- (a) Incorrect. The Painted Stork fishes in wetlands and does not follow cattle.
- (b) CORRECT. Only the Common Myna stalks alongside cattle for insects.
- (c) Incorrect. The Black-necked Crane lives in cold high-altitude wetlands.
- (d) Incorrect. The Black-necked Crane does not follow cattle in the countryside.
Key point
Common myna and cattle egret follow cattle for disturbed insects (commensalism). Painted stork: wetland fish-eater. Black-necked crane: Ladakh.
Remember
Myna and cattle egret follow cattle.
Common mistakes
- Assuming all large birds near fields follow cattle.
- Confusing the painted stork with the cattle egret.
- Forgetting that the black-necked crane is a Himalayan bird.
Exam tip
Think habitat: stork in water, crane in Ladakh, myna in the fields.
Sources
- NCERT Class XII — Biology (Organisms and Populations: commensalism)
- Bombay Natural History Society — Salim Ali, The Book of Indian Birds