The parents may cease to eat at this point in order to be able to provide the squabs (baby pigeons and doves) with milk uncontaminated by seeds, which the very young squabs would be unable to digest. Pigeon's milk begins to be produced a couple of days before the eggs are due to hatch. Unlike mammalian milk, which is an emulsion, pigeon crop milk consists of a suspension of protein-rich and fat-rich cells that proliferate and detach from the lining of the crop. Like mammalian milk, crop milk contains IgA antibodies. It has also been shown to contain anti-oxidants and immune-enhancing factors which contribute to milk immunity. A 1939 study of pigeon crop milk showed, however, that the substance did not contain carbohydrates (sugars), unlike mammalian milk. It is extremely high in protein and fat, containing higher levels than cow or human milk. Pigeon milk is a semi-solid substance somewhat like pale yellow cottage cheese. Pigeon milk Ĭrop milk bears little physical resemblance to mammalian milk, though in pigeons its compositionally similar. Crop milk contains both fat and protein, as with mammalian milk, but unlike mammalian milk, it contains no carbohydrates.

Crop milk is a holocrine secretion, unlike in mammals where milk is an apocrine secretion. Lactation in birds is controlled by prolactin, which is the same hormone that causes lactation in mammals. Unlike in mammals where only females produce milk, crop milk is produced by both males and females in pigeons and flamingos and in penguins, only the male. Crop milk is also secreted from the crop of flamingos and the male emperor penguin, suggesting independent evolution of this trait. It is found among all pigeons and doves where it is also referred to as pigeon milk. Crop milk is a secretion from the lining of the crop of parent birds in some species that is regurgitated to young birds.

Flamingo albert milk