The first known connection between love and birds appears in the British medieval poet Geoffrey Chaucer's work "Parliament of Fowls," in which the poet writes of birds choosing mates on Valentine's Day. Another 14th century poet, Otto de Granson, began the practice of writing Valentine's Day poetry but did not mention birds until one of his last poems.
Another origin for the concept of two people in love being 'lovebirds' may come from a species of parrot within the genus Agapornis. These small parrots are colloquially called lovebirds, and they are known to form lifelong, monogamous mating bonds. This pairing habit, combined with the birds' affectionate nature, earned them the colloquial name of lovebirds.