Hi Jane. It is quite common for racing or homing pigeons to join up with Ferals. By doing so they learn to forage and stand more chance of survival. Many stranded or exhausted homing pigeons are not fortunate to find their Feral cousins and die of starvation as they have no foraging skills. The Pigeon rescue people that I know caution against contacting owners of lost or stranded pigeons. This is because in some cases the birds might not be considered as fit for racing and are disposed of. This is not true of all pigeon fanciers, but I wouldn't take the chance. Maybe you could try squirrel proof feeders. That might deter the Ferals?
Unicum arbustum haud alit duos erithacos
(One bush does not shelter two Robins)
Zenodotus (3rd Century B.C.)
Thank you very much for you answer and advice monkeycheese and also for confirming my suspicions about the ringed pigeons having been ex racers who joined the feral flock. I'll try the squirrel proof feeders for the smaller birds and keep feeding the pigeons too!