The bones of birds are long and hollow withh air cavities. These types of bones are called as:

Answer

To solve the question regarding the type of bones found in birds, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Characteristics of Bird Bones**:
- The question mentions that the bones of birds are long and hollow with air cavities.

2. **Understand the Function of These Bones**:
- The hollow structure of these bones is essential for flight. They help in reducing the overall weight of the bird, making it easier for them to fly.

3. **Learn the Term for These Bones**:
- The specific term used to describe the bones that are hollow and contain air cavities is "pneumatic bones."

4. **Differentiate from Other Types of Bones**:
- Unlike the solid bones found in many other animals (like humans), pneumatic bones are designed to be lightweight and are filled with air spaces.

5. **Conclude the Answer**:
- Therefore, the answer to the question is that the bones of birds are called "pneumatic bones."

### Final Answer:
The bones of birds are called **pneumatic bones**.

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