In most locations, yes. Check with your location's Department of Wildlife (may be called something else, like "Department of Fish & Game") to see if it's true in your area for the specific type of animal you're interested in.
In some cases, injured or orphaned animals may be temporarily cared for by private citizens, but this usually requires the explicit permission of and supervision by the department to insure that it is not being raised as a pet; the goal in such cases is to eventually release it back into the wild.
In what country? The answer depends on too many things. In most countries it is illegal to remove most eggs from the wild, but in almost all there are exceptions.
First of all, you probably shouldn't keep a WILD bird, because they are meant to be WILD and it's not right to keep them. It's fine to keep a "domestic" bird, but not a WILD bird.
in some states
it is not illegal but you must make sure you report it
The ministry of fisheries,environment and agriculture is responsible for keeping up the fish hatcheries bird sanctuary's and wild refugees.
No, but they won't last long.
Different bird species require different diets, and there are many bird species that could be found in any given area. Simply knowing the geographic location is not enough to narrow down what would be an appropriate food. If you find a wild baby bird, your best option is to find a licenced wild bird rehabilitator. In most cases, keeping native bird species without a license is illegal in the United States. "Keeping" includes hand-rearing orphaned baby birds.
yes it is.
In the U.S., it is, and in many other lands as well.
In most countries it is ILLEGAL to collect or POSSES wild bird eggs.
This depends on the species. Some birds are protected. There are species which you may be able to look after but cannot release back into the wild. The best thing to do with a wild bird is to consult a Vet.
No debate, it is illegal by NM and Federal laws
From a sanctuary or simply by finding an injured raven to rehabilitate. Ravens are wild animals, and are therefore illegal to own or purchase under normal means. Look to your local bird sanctuary to volunteer.
It's illegal to keep any wild animal in the United States unless you have a permit or a licence.
a very wild bird is an ostrich.