In pigeons and doves, a male brings sticks and other materials and a female assembles a loose nest. They are unique among birds in making milk to feed their young. Distinct from mammal milk, it is made in a pouch on the bird's throat (the crop). Males and females both start to make crop milk just before eggs hatch. They tend to lay just one or two eggs, and the thick, high-protein milk sustains hatchling pigeons and doves (squabs) for their first week or so. After a week, their digestive system is ready for the mature diet of seeds or fruits. Parents include adult food with the crop milk, continuing to feed squabs for up to a month. If a squab dies, the other squab gets extra milk and grows bigger quickly. When a hawk or other predator approaches the nest, the parents may pretend to be injured, using a broken-wing display to distract the predator.