Cargo pigeons

Pigeons have remarkable homing abilities. Flying long distances back to their roost. For years this has been used to send mesages, and for racing. But now with the arrival of Genetic technology why not engineer bigger pigeons? Pigeons that have a useful cargo capacity? Big enough for small items at first, parcels and the like then gradually building over time to full light cargo carriers. They could be trained to swallow small items and carry them in their crops or just tied to their legs as with messages. They'd not be a big as a cargo jet but they'd be emmision free, relativly cheap to maintain and are their own pilots. You'd not even need to worry about trafic control if "Pigeon lanes" were set up through wich conventional aircraft cannot fly. Airports would cease to be so noisy, the roar of the jets replaced by the sound of deep coos of giant cargo pigeons resting between flights. The feeding troughs and preening technicians. Company logos sprayed on their wings. However while airports would cease to be such big noise poluters, the smell would need looking into. The droppings could be collected and sold to farmers for fertiliser.