What can I do to save the life of a domestic pigeon?

Time is critical usually. Place the bird in a paper or towel lined cardboard box and place the box atop of a heating pad set on low. Be sure the box has openings for air.

Never force water down a bird's gullet. Get in touch with a local Re-habber as fast as possible to discuss symptoms etc. until then, keep it calm, warm, and place a small water bowl and seed,  or broken up dry dog food if that is all you have for the bird to access. There are too many reasons for a downed bird. You have to go case by case. Volunteer somewhere so you might be more prepared in the future. It can be really rewarding.

Hi there, you would have to give me more information as to what is wrong with the pigeon. Food and water are an obvious start. Let me know.