I have seen it many times, more than I can count. I have heard it from others many times too. It seems possible and even probable that some animals notice and do in fact distinguish children from adults. Is it possible that it is their energy, the literal physical size.
Some animals have more patience and tolerance with small children than adults. “My son pulls on his ears and he just stands there.” “My daughter tries to ride the dog and he allows her to try to climb on him.”
This of course isn’t true of all animals. Some of them have grown tired and weary of young children petting them too hard or too abruptly, being chased by them or having an ear or a tail pulled. It is not surprising that some animals avoid children, hiss or growl at them and unfortunately even bite them.
It is wise for parents and older siblings to make sure that both animals and young children are safe. Teaching young children to respect animals who don’t want to be touched and to pet them gently is healthy for all involved.