Captain Hall expressed some doubts as to my views respecting the affection and love of pigeons, as if I made it human, and raised the possessors quite above the brutes. I presume the love of the mothers for their young is much the same as the love of woman for her offspring. There is but one kind of love; God is love, and all his creatures derive theirs from his; only it is modified by the different degrees of intelligence in different beings and creatures.

Ch. X, p. 139 - The Life and Adventures of John James Audubon, the Naturalist (1868)