Baby birds
Jumping on the ground, possibly beeping and whistling, young songbirds (blackbird, thrush, tit, etc.) usually do not need help! These are birds that have already left the nest but can't fly yet, so they hop around and beep to call their parents who are still feeding them!
Only if the bird is moving along a busy road, if there is a dog or cat nearby or if small children want to play with it, then carefully pick it up and move it to the nearest bush or tree within a radius of approx. 20-25 m, where, according to the beeping, the parents can safely find it and feed it.
Birds do not have a good sense of smell, so there is no danger that the parents will reject the chick after your touch!
It is the same with young raptors and owls, when young owls sit on the branches of the "native tree" and young kestrels on the ledges and windowsills of nearby houses. If they are on the ground and have no obvious injuries, then place the young owl on the branch of the nearest tree and the kestrel on a windowsill, ledge or balcony, if possible at least on the second floor. If there is no other way, do not be afraid to move the cub to a suitable place even 30 m from the place of discovery, the cub loudly demands food and the parents will find it and feed it without any problems.
Young rorys require different care. The common swift is a bird that spends its entire life (outside of nesting) in the air. It has long wings and short but strong legs, with the help of which it hangs on the vertical walls of prefab houses, in the ventilation holes of which it likes to build its nest. Due to its short legs, it needs an elevated place to take flight, from which it literally "washes away". Picking up a young rory on a branch is therefore pointless. Help consists in returning the chick to its original or adoptive nest as quickly as possible, which is a job for an experienced ornithologist. Place the young rory in a paper box of an appropriate size and hand it over to the nearest rescue station.
Young non-feeding birds
Chicks of pheasants, partridges and quails, ducks, geese, young swans stay with their siblings for several weeks near their parents. If you find a lone cub and its parents are definitely not in sight, then place it in a paper box of the appropriate size and hand it over to an animal rescue station as soon as possible.