Years ago, when my kids were young, we were out walking and our dog went in a garden and discovered a young swift It may have fallen out of its nest . Its wings were not ready for flying.
I actually thought that its legs were damaged as it seemed unable to walk. Anyhow, I rang the RSPCA and they told me how to feed it. Swifts are high-protein eaters, so baby swifts need to eat cut-upworms, cut-up egg yolk, and cut up raw meat. We named him Jonathan.
His first meal - tiny pieces of chopped egg yolk - he refused to open his beak. I had to carefully prise his beak open and dropped some cooked egg yolk in. After a few beak fulls he realised he was being fed and was waiting with beak agape. From then on when it was feeding time he fed readily and when he was full he clamped his beak shut.
I was given the number of a farmer’s wife who lived in the country, who was wel known locally for rescuing birds. When I told her that Jonathan was unable to walk, she told me that that is normal for swifts - they have very weak legs. If he needed to get from point A to point B he would grab a piece of carpet with his beak and haul himself slowly where he wanted to go. I was amazed, but th upside of this (handicap) is that swifts have incredible wings and are master flyers. They eat (flying insects ) take forty winks, and almost totally live their lives in the air. They never land on the ground. But they do build nests up high.
Jonathan was living in a large cardboard box, ( segregated from the cat and dog ) After a day or two I noticed he wa perched on the edge of his box energetically flapping his wings .
This is how they strengthen their wings for flight. He exercised his wings for days and Janice ( the farmer lady ) told me it was time to take him out for flying practice. I was to throw him up into the air a bit, so he could gain momentum. I tried this a few times - he could fly vertically, but couldn’t gain height. She told me that his wing feathers needed to grow some more. He could fly vertically and then would plop down out of sight somewhere. So she took pity on me and told me to bring Jonathan to her and she and her husband would oversee his final care before release. It worked out very well and about a week later she told me that they had successfully released him . He had taken to the sk,y, did about three circles around the farm and then flew off, presumably to find some other swifts.