In a general sense, mourning in the Bible represents a state of grief over the lack of desires for good and true ideas about life. This often happens when a church or an aspect of a church has fallen away from the Lord and has been devastated. It can also be when a new church or state of a church is soon to begin, and there is nothing yet in place. In particular, especially when paired with "weeping," "mourning" has do with the loss of all desire for good and the presence of evil; "weeping" in those cases has to do with the devastation of thought and knowledge.

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.

(References: Arcana Coelestia 777; Hosea 2)