Give four peculiar characters of birds.

Explanation

### Step-by-Step Solution:

1. **Presence of Feathers**: One of the most distinctive features of birds is the presence of feathers. Feathers are unique to birds and serve various functions, including insulation, waterproofing, and aiding in flight.

2. **Beak and Modified Forelimbs**: Birds possess a beak instead of teeth, which is adapted to their feeding habits. Additionally, their forelimbs are modified into wings, allowing most birds to fly, although some species, like ostriches, are flightless.

3. **Dry Skin with Oil Gland**: The skin of birds is dry and lacks sweat glands. However, they do have an oil gland located at the base of their tail, which helps in maintaining the waterproof quality of their feathers.

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