Feathers present over nestlings are

Options

A. down
B. contour
C. filoplumes
D. quill

Answer

To answer the question "Feathers present over nestlings are," we need to analyze the options given and understand the characteristics of each type of feather mentioned.

### Step-by-Step Solution:

1. **Understanding the Types of Feathers**:
- **Down Feathers**: These are small, soft, and woolly feathers that lack a central shaft (rachis). They are primarily responsible for providing insulation to birds, especially to nestlings.
- **Contour Feathers**: These feathers form the general covering of a bird's body. They have a central shaft and are structured to reduce drag during flight. They are not primarily for insulation.
- **Phylloplumes**: These are delicate, hair-like feathers that serve an unclear function and are sparsely distributed on the body. They are not significant for insulation.
- **Quill Feathers**: Also known as flight feathers, these are strong and have a well-defined structure with barbules. They are essential for flight but do not provide insulation for nestlings.

2. **Identifying the Correct Feather Type**:
- Since the question specifically asks about feathers present on nestlings, we focus on the function of insulation. Down feathers are specifically designed to provide warmth and insulation to newly hatched birds.

3. **Conclusion**:
- Based on the characteristics and functions of the feathers discussed, the feathers present over nestlings are **down feathers**.

### Final Answer:
**Down feathers** are the feathers present over nestlings.

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