Serin
Crowing
Too late to make a difference in this case but to future readers that will see this.. Pigeons are a domesticated animal and if they are hand raised their odds of survival are very low if set free. They're even worse for birds with unnatural coloring. Pigeons outside the sea coasts of western Europe are feral donesticated animals. Letting captive raised birds loose is similar to releasing a kitten when it is ten weeks old. It might survive and cats do live feral but they don't live very long or good lives and without learning skills from their parents the pigeons stand very little chance. In this case the bird has been socialized with a predator species which is a huge no no in wildlife rehab (which pigeons are not anyway.) He might do ok in the setting you be released him in if food is provided and the house is predator proof.
Hand raised pigeons should ideally be placed in pet homes or with a loft of captive birds that will be provided food, shelter and a flock for protection from predators.
Hand raised pigeons should ideally be placed in pet homes or with a loft of captive birds that will be provided food, shelter and a flock for protection from predators.