What is woodpigeon milk?

Kirsi Peck Supporter Adviser I have a life-long interest in wildlife and birdwatching. Having completed my PhD on woodland birds, I joined the RSPB in 1990, first as a member of the research department, later in Wildlife Enquiries. I write and manage many information leaflets, and have extensive knowledge of bird biology, habitat management, wildlife law, planning and many other subjects.

Sent in by Shirley Walters, Milton Keynes

Pigeon's milk is not really milk at all, but a secretion produced by pigeons to feed their chicks with.

Both the male and the female start to produce it just before the time their chicks hatch. The secretion is also known as crop milk, since it is produced from special cells in the crop, a sac-like distension in the digestive system where birds store food.

The parent birds regurgitate the crop milk to their chicks. At first, the chick eats nothing else, and it thrives on the extremely high protein and fat content of the milk.

As the chick grows, increasing amount of other crop contents, such as seeds and grass, are added to the feeds. By the time the chick is ready to fledge, parent birds have stopped producing the milk, and the chick receives the normal adult diet.

Very few bird species produce milk. Apart from all species of pigeons and doves, this is only fully documented in the greater flamingo and emperor penguin.

Comparable secretions are found in certain other birds. For instance, fulmars feed their young with a mixture of regurgitated crop contents and a very rich stomach oil. They produce the stomach oil all year, not only during the breeding season. Being foul-smelling, the oil is also used to drive away a predator.