Life Sciences Paper 1, November 2024, question 3.1.3

Pigeons are birds that nest in sheltered spots such as ledges and roof corners. A female pigeon usually lays two eggs, and both parents take turns to keep them warm until they hatch. After hatching, the parents feed the young on a milk-like substance produced in their crops. The young stay in the nest for about four weeks before they can fly. Birds whose young hatch in this way are said to show altricial development.