Some birds give their offspring milk; a trait we often tend to think that only mammals are capable of!

When I tell people that some birds produce and feed their offpring with milk, they often think I’m joking. However, this is a completely true fun-fact that you should go ahead and tell your friends all about, because it is a fact that some birds actually produce a kind of milk that they give to their hatchlings.

The crop milk, as it is called, is produced by the parent bird and regurgitated from the mouth, so they don’t really breastfeed like most mammals do. It does not really look like regular milk, but instead reminds us of a yellowish cottage cheese type of substance. It has a higher level of both fat and protein than human or cow milk, so it is extremely nutritional. It might not really remind us of milk, but it is technically a type of milk, just not as liquid as we are used to.

A greater flamingo (Phoenicopterus roseus) feeding its hatchling with crop milk. Image by Robin Müller, posted with the Creative Commons Attribution-Share Alike 3.0 Unported license.

Just like with mammals, the hormone that controls the milk production is the prolactin, so it is based on the same hormone to start production. It also shares a few other traits with mammalian milk, such as having some bacteria contained in the milk, and containing IgA antibodies. Both these are useful to the newly born bird, giving it a head-start in terms of build an immune system.

So, which birds produce milk?

There are only a few types of birds that produce milk for their offspring, and we find most of the bird species to be either doves or pigeons. These both belong to the family Columbidae, and all 310 species produce crop milk. In addition to this the four flamingo species produce crop milk, as well as a few species of penguins.

So most birds to not do this, but we find some examples of it. It’s really cool that all pigeons and doves do it, because these are pretty common birds, so all of you have seen a milk-producing bird!

Thanks for reading!

I hope you enjoyed this quick funfact about milk production in birds! Don't be afraid to leave a comment below if you got anything you want to share with the rest of us :)