Crop milk is a secretion from the lining of the crop of parent birds in some species that is regurgitated to young birds. It is found among all pigeons and doves where it is also referred to as pigeon milk. Crop milk is also secreted from the crop of flamingos and the male emperor penguin,[1][2][3] suggesting independent evolution of this trait.[4] Unlike in mammals where typically only females produce milk, crop milk is produced by both males and females in pigeons and flamingos; and in penguins, only by the male.[5] Lactation in birds is controlled by prolactin, which is the same hormone that causes lactation in mammals.[6][5] Crop milk is a holocrine secretion, unlike in mammals where milk is an apocrine secretion.[5] Crop milk contains both fat and protein, as with mammalian milk, but unlike mammalian milk, it contains no carbohydrates.[5]
- ^ Levi, Wendell (1977). The Pigeon. Sumter, S.C.: Levi Publishing Co, Inc. ISBN 0-85390-013-2.
- ^ Silver, Rae (1984). "Prolactin and Parenting in the Pigeon Family" (PDF). The Journal of Experimental Zoology. 232 (3): 617–625. doi:10.1002/jez.1402320330. PMID 6394702. Archived from the original (PDF) on 13 September 2016.
- ^ Eraud, C.; Dorie, A.; Jacquet, A.; Faivre, B. (2008). "The crop milk: a potential new route for carotenoid-mediated parental effects" (PDF). Journal of Avian Biology. 39 (2): 247–251. doi:10.1111/j.0908-8857.2008.04053.x.
- ^ Ornithology, British Trust for (2012-08-22). "Crop milk". BTO - British Trust for Ornithology. Retrieved 2023-04-30.
- ^ a b c d Ann M. Ward, Amy Hunt, Mike Maslanka, and Chris Brown, Nutrient Composition Of American Flamingo Crop Milk (PDF)
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