Dickon always spoke it to the robin himself, so the queer gibberish he used when he spoke to humans did not matter in the least.

The robin thought he spoke this gibberish to them because they were not intelligent enough to understand feathered speech.

His movements also were robin.

They never startled one by being sudden enough to seem dangerous or threatening.
Any robin could understand Dickon, so his presence was not even disturbing.
But at the outset it seemed necessary to be on guard against the other two.

In the first place the boy creature did not come into the garden on his legs.