This advice relates to garden birds, this being the most common type of baby bird encountered by humans and is taken from www.helpwildlife.co.uk from their excellent advice sections.
There is a great deal of misinformation about what you should do with baby birds and a great number of birds die unnecessarily as a result. Certain national domestic animal charities run huge campaigns each year telling the public never to pick up a baby bird. If you call them you'll be told to leave the bird alone regardless of the situation, any injuries and the age of the bird. It certainly is important not to interfere when not needed but each situation should be assessed individually by a wildlife expert. There is no one single appropriate response to a baby bird situation.
The sad fact is that baby bird casualties run into many many thousands each year. Caring for them is extremely resource intensive, pretty mundane, messy and sometimes disappointing as a fair number will die. As a result some organisations are keen to avoid taking them in and not above giving out incorrect information to achieve this. The advice which follows is unbiased. It is based on many years of experience in caring for baby birds but with nothing to gain from giving you incorrect information. Our only motive is ensuring that baby birds are given the help they need when they need it.
The first and most important thing to remember - the golden rule - is that any bird which has been caught by a cat, regardless of it's age, will need treatment. There are bacteria on cats teeth which will pass into the birds bloodstream when it is bitten. Without antibiotics within a few hours of the attack the bird may develop fatal septicaemia.
The second most important thing to know is that baby birds are fed by their parents as often as every 15 minutes. If they are not fed regularly then they actually start to digest their own stomachs, causing irreparable damage. So if you do find a baby bird you must seek assistance urgently. If you cannot get it to a wildlife rescue quickly, then either keep it somewhere completely dark (which will send the bird to sleep and it will not then need to feed) or feed it every quarter of an hour with moistened cat food (apart from baby pigeons (see below) or waterfowl). Never feed worms (some are toxic), milk or alcohol (very dangerous old wives' tales).
On the subject of old wives' tales it is not the case that parent birds will reject their babies once they have been touched by humans. Birds have quite a poor sense of smell and recognise their young through the sound of their call. So you can safely handle a baby bird to assess it for injuries or move it to safety without fear of upsetting Mum and Dad.
A baby bird may need rescuing if:
the bird has been caught by a cat
the bird is obviously injured
the bird is out if its nest and is not feathered (return to the nest if possible, if not it will need rescuing)
the bird is out of its nest, only partially feathered (eg its tail is short and it still has a fluffy appearance) and there is no sign of any parent birds for a couple of hours
the nest has been destroyed and the occupants are not fully feathered
the bird is in immediate danger from a cat, cars or any other threat. You can try placing the bird in a bush or low branch of a tree but if it is still in danger it will need rescuing.
both parents have been killed
Do NOT intervene if:
the bird is fully feathered, not injured and not in immediate danger. The bird is probably a fledgling taking its first flight. If possible place the bird in a hedge or low branch of a tree to keep it safer. Observe to make sure the bird remains safe.
Thanks to the site www.helpwildlife.co.uk for allowing us to use their advice sheets. Please visit their site for more information on helping wildlife and spread the word amongst your friends.