The droppings in the one photo indicate starvation droppings (green and creamy). If he has not started eating yet, you will need to handfeed him. Defrost frozen peas in warm water and place one at a time deep inside the beak over the tongue. Feed about 20 peas and when that gets digested (droppings will become bulkier) feed 20 more. An adult pigeon needs abput 150 peas divided into 3 meals of 50 each (depending on how quick the crop empties).