Question

Based on data (Birds decline, Plants % decline, Area decline), interpret two reasons for change in the population of migratory birds. 

 

Hint:

In data-based questions, always link your biological reasoning directly to the variables shown in the table columns.

Answer 1

Step 1: Observe the trend in bird population.
From the data, the population of migratory birds has declined over the three years:
• 2023 → 10,000 birds
• 2024 → 8,000 birds
• 2025 → 5,000 birds

This shows a continuous decrease in bird population over time.

Step 2: Observe the change in aquatic plants.
The percentage of aquatic plants has also decreased:
• 2023 → 85%
• 2024 → 60%
• 2025 → 45%

Aquatic plants provide food and shelter for migratory birds. The reduction in aquatic vegetation reduces food availability and habitat quality for these birds.

Step 3: Observe the reduction in aquatic area.
The aquatic area has also declined significantly:
• 2023 → 350 ha
• 2024 → 280 ha
• 2025 → 220 ha

This indicates loss of wetland habitat, which is essential for migratory birds for feeding, resting, and nesting.

Final Answer:
Two main reasons for the decline in migratory bird population are:
1. Decrease in aquatic plants, leading to reduced food and shelter for birds.
2. Reduction in aquatic area (wetland habitat loss), which limits the space available for feeding and breeding.