Causes of extinction of stellar's sea cow of Russia and passenger pigeon is

Options

A. over-exploitation by humans
B. alien species invasion
C. habitat loss and fragmentation
D. co-extinction

Answer

### Step-by-Step Solution:

1. **Understanding the Question**: The question asks for the causes of extinction of two specific species: the Steller's sea cow and the passenger pigeon.

2. **Identifying Key Factors**: The video transcript mentions four main reasons for biodiversity loss or extinction:
- Over-exploitation by humans
- Alien species invasion
- Habitat loss and fragmentation
- Co-extinction

3. **Analyzing Each Factor**:
- **Habitat Loss and Fragmentation**: This refers to the breaking up of large habitats into smaller, isolated patches due to human activities. This can lead to a decline in species populations as their living space is reduced.
- **Over-exploitation**: This is when humans excessively use natural resources for food, shelter, and other needs, leading to a decline in species populations. This was highlighted as a significant factor for both the Steller's sea cow and the passenger pigeon.
- **Alien Species Invasion**: The introduction of non-native species can disrupt local ecosystems and lead to the decline of indigenous species. However, this was not the primary cause for the extinction of the two species in question.
- **Co-extinction**: This occurs when the extinction of one species leads to the extinction of another species that depends on it. While important, it was not the main reason for the extinction of the Steller's sea cow and passenger pigeon.

4. **Conclusion**: The main reason for the extinction of both the Steller's sea cow and the passenger pigeon is **over-exploitation by humans**. This excessive hunting and resource use led to their population decline and eventual extinction.