What does Fo Yin mean by being right in the joke "Monks and birds are opposites"?

Su Dongpo, a young Fo Yin, said that "bird" and "monk" always appear correspondingly. For example:

Birds stay in trees by the pool, monks knock on the moon and next month' and' when you smell woodpeckers, you suspect that you are knocking at the door. Do you understand the meaning of these two sentences? No translation.

Su Dongpo quoted these two sentences to illustrate a coincidence in ancient literary poetry. Monks and birds occasionally appear in some sentences.

The old monk in Fo Yin smiled humorously and said, "Today, the old monk is a bird to Xianggong."

Right: Facing me, facing you, you are just a "bird", and we communicate together.