All of the following are true about birds except .

Options

A. Preen glands at the base of tail
B. Alimentary canal has crop and gizzard
C. Endoskeleton is fully ossified
D. All of them can fly

Answer

To solve the question "All of the following are true about birds except," we need to analyze each statement provided and identify the one that is false.

### Step-by-step Solution:

1. **Examine the first statement: "Print glands at the base of the tail."**
- Birds have uropygial glands (also known as print glands) located near the base of their tail. These glands secrete oil that birds use to preen their feathers.
- **Conclusion:** This statement is true.

2. **Examine the second statement: "Elementary canal has crop and gizzard."**
- The digestive system of birds includes a crop, which stores food, and a gizzard, which grinds food. This is a characteristic feature of their anatomy.
- **Conclusion:** This statement is true.

3. **Examine the third statement: "Endoskeleton is fully ossified."**
- Birds have a highly ossified endoskeleton, which means their bones are solid and strong. This adaptation helps in flight as it provides structural support while keeping the weight low through hollow bones.
- **Conclusion:** This statement is true.

4. **Examine the fourth statement: "All of them can fly."**
- While many birds can fly, there are exceptions such as ostriches, penguins, kiwis, and rheas, which are flightless birds.
- **Conclusion:** This statement is false.

### Final Answer:
The statement that is not true about birds is: **"All of them can fly."**

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