If the hatchling is too immature to leave the nest, carefully pick it up and return it to its nest. If you are unable to locate the nest, or if it is inaccessible or damaged, line a tiny basket, such as a pint berry basket, with tissue or grass clippings and hang it as close to the nest location as feasible. Place the hatchling in the basket, cover it with more tissue or grasses, and place the basket in a safe location where it will not be disturbed by people or animals. The hatchling will grow feathers and open its wings, and when ready, it will fly off into the future.
Of all the birds we take care of at the zoo, baby birds hit us hardest at first glance. They're so small and helpless, and they need help getting over their initial fear of humans. However, it's important to remember that although they may appear fragile, many baby birds are actually quite resilient. It's likely that if they were returned to their nest, they would survive despite being alone for awhile.
If they can't locate it, they could abandon their children.
The best thing to do is to return the baby to the nest, if there is one. If you find nestlings in your yard, try for a nest within a few yards of where the bird was discovered. Replace the nestling as soon as possible if it can be done safely. Don't attempt to replace the eggs or the parent birds. If you cannot locate a nest, then call your local wildlife organization or pet store and ask them how to handle the situation.
In addition to replacing nests and babies, there are several other options for dealing with orphaned birds. An animal rescue group or wildlife rehabilitator may be able to take the bird in. A foster home or even an individual who wants to help out but isn't willing to adopt the bird can provide food and water for it while it recovers.
Finally, some species of birds will attack anything that looks like food so don't worry about hurting the bird by keeping it as a pet.
You can remove the nest if it is empty and the birds have moved on. Just be certain that the nest has been actually abandoned. The easiest way to be sure is to keep an eye on it for a week or so and see if any birds return. If not, you can get rid of the nest. Avoid getting wet feet when removing the nest from inside the building though, as this could be dangerous.
If you find that you are unable to remove the nest because it's stuck fast within the wall, there are several things you can try. First of all, make sure that you aren't trying to remove the nest from inside a wall cavity. If you go about it from the outside, you have greater chance of being successful.
Secondly, if possible, try to locate the nest within the wall before you start working. This will allow you to avoid breaking off small pieces of wood which may later need to be repaired.
Thirdly, try not to irritate the birds by making lots of noise while you work. This could cause them to defend their nest aggressively, thereby preventing you from taking it out.
Finally, remember that bird nests are basically just bulky objects which can get in the way when repairing walls or ceilings. So take your time and don't worry about ruining the structure of the house - you'll have another one soon enough!