Fowl signify spiritual truth; a bird, natural truth; and a winged thing, sensual truth. Fowl of heaven, as in Hosea 2:18, signify the affections of truth; and reptiles of the earth, the affection of the knowledges of truth and good. Fowl signify thoughts, and all that creeps on the ground, the sensual principle. Fowl signify intellectual things.

(Reference: Arcana Coelestia 777; Hosea 2)

777. That 'bird' means spiritual truth, 'flying thing' natural truth, and 'winged thing' sensory truth, is clear from what is said above, as also is the fact that truths are in this way different. Sensory truths, which come through seeing and hearing, are called 'winged things' because they are outermost. 'Wing' has a similar meaning when applied to other things.