Should you feed baby pigeon

As often as they are fed, or if they are precocial (they leave the nest after hatching - like chickens), as often as they find food. It also depends on the species - some sea-birds in particular may be fed only once a day or even less often. For most garden birds, in good weather and good habitat, chicks will eat every few minutes, but they can only go for a day or so with very little to eat before they will die.