Write a sentence using the words 'ball', 'tree', and 'pigeon'.
A pigeon perched on the branch of a tree, carefully observing the children playing with a ball below.
Complete the following task based on the instruction and optional input provided.### Instruction:
Write a sentence using the words 'ball', 'tree', and 'pigeon'.

### Output:
A pigeon perched on the branch of a tree, carefully observing the children playing with a ball below.