Bailly-Maitre, a breeder of great knowledge and a keen observer, wrote to Girard that "they are strange creatures in their manners and customs and are apt to elude the most persistent observer.

No animal is more depraved.

Mating between males, and still more frequently between females, often occurs at an early age: up to the second year.

I have had several pairs of pigeons formed by subjects of the same sex who for many months behaved as if the mating were natural.

In some cases this had taken place among young birds of the same nest, who acted like real mates, though both subjects were males.