Why do birds and mammal not hibernate during winter as is seen in most animals?

Explanation

### Step-by-Step Solution:

1. **Understanding Hibernation**:
- Hibernation is a state of deep sleep that some animals enter during winter to conserve energy when food is scarce. This process is also referred to as "winter sleep."

2. **Identifying Hibernating Animals**:
- Hibernation is primarily observed in poikilothermic animals, which are unable to regulate their body temperature. These animals rely on the external environment to maintain their body temperature.

...