For which reason, whatever else there may be in the writings of Moses which excites my wonder, I would say that the following is worthy of admiration, viz., that Moses, having observed the varying natures of animals, and having either learned from God what was peculiar to them, and to the demons which are kindred to each of the animals, or having himself ascertained these things by his own wisdom, has, in arranging the different kinds of animals, pronounced all those which are supposed by the Egyptians and the rest of mankind to possess the power of divination to be unclean, and, as a general rule, all that are not of that class to be clean.
And among the unclean animals mentioned by Moses are the wolf, and fox, and serpent, and eagle, and hawk, and such like. And, generally speaking, you will find that not only in the law, but also in the prophets, these animals are employed as examples of all that is most wicked; and that a wolf or a fox is never mentioned for a good purpose. Each species of demon, consequently, would seem to possess a certain affinity with a certain species of animal. And as among men there are some who are stronger than others, and this not at all owing to their moral character, so, in the same way, some demons will be more powerful in things indifferent than others; and one class of them employs one kind of animal for the purpose of deluding men, in accordance with the will of him who is called in our Scriptures the “prince of this world,” while others predict future events by means of another kind of animal.
Observe, moreover, to what a pitch of wickedness the demons proceed, so that they even assume the bodies of weasels in order to reveal the future! And now, consider with yourself whether it is better to accept the belief that it is the Supreme God and His Son who stir up the birds and the other living creatures to divination, or that those who stir up these creatures, and not human beings (although they are present before them), are wicked, and, as they are called by our Scriptures, unclean demons.
Source: Against Celsus (New Advent)