A major cause of mortality of many birds visitors of aquatic habitat is
(a) Nutrient enrichment
(b) Lead poisoning
(c) Salt enrichment
(d) All the above

Options

A. Nutrient enrichment
B. Lead poisoning
C. Salt enrichment
D. All the above.

Answer

To solve the question regarding the major cause of mortality of many bird visitors of aquatic habitats, let's analyze the options step by step:

1. **Understanding the Question**: The question asks for a major cause of mortality among birds that visit aquatic habitats. We need to identify which of the provided options is the most significant factor.

2. **Evaluating Option A - Nutrient Enrichment**: Nutrient enrichment refers to the increase in nutrients, often due to runoff from agricultural areas. While it can lead to algal blooms and decreased oxygen levels, it does not directly cause mortality in birds. Therefore, this option can be excluded.

3. **Evaluating Option B - Lead Poisoning**: Lead poisoning occurs when birds ingest lead, often from fishing tackle or contaminated water. This condition can be fatal for birds, making it a significant cause of mortality. This option remains a strong candidate.

4. **Evaluating Option C - Salt Enrichment**: Salt enrichment can occur due to various factors, including agricultural runoff or de-icing agents. While it can affect aquatic life, it is less likely to be a major direct cause of mortality in birds compared to lead poisoning. Thus, this option can also be excluded.

5. **Evaluating Option D - All the Above**: Since we have determined that options A and C are not major causes of mortality, this option can also be excluded.

6. **Conclusion**: After evaluating all the options, the most significant cause of mortality for many bird visitors of aquatic habitats is **lead poisoning** (Option B).

Final Answer: (b) Lead poisoning

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