Excretory matter in bird is

Options

A. ammonia
B. uric acid
C. guanine
D. urea

Answer

### Step-by-Step Solution

1. **Understanding Excretion**:
- Excretion is the process of eliminating nitrogenous waste from the body. This waste primarily comes from the breakdown of proteins and nucleic acids.

2. **Sources of Nitrogenous Waste**:
- Proteins and nucleic acids are broken down into amino acids and nitrogenous bases, respectively. The amino groups from these compounds need to be eliminated from the body.

3. **Types of Nitrogenous Waste**:
- There are three main forms in which nitrogenous waste can be excreted:
- **Ammonia**: Excreted by ammonotelic organisms (mostly aquatic animals like fish).
- **Urea**: Excreted by ureotelic organisms (such as mammals and adult amphibians).
- **Uric Acid**: Excreted by uricotelic organisms (including insects, reptiles, and birds).

4. **Excretion in Birds**:
- Birds belong to the category of uricotelic animals, meaning they excrete nitrogenous waste in the form of uric acid. This adaptation helps conserve water, which is crucial for survival in their often arid environments.

5. **Conclusion**:
- Therefore, the excretory matter in birds is uric acid.