Many birds will nest in areas that may be less than convenient for people. Prevention is the key to this situation.
If a bird is in the process of building a nest in a problem area but no eggs are present the nest can be taken down. This may take a little repeating but the bird will quickly get the idea this area is not suited for raising a family. Placing vertical sticks or twigs in potted or hanging plants can also help prevent nest building. Metallic streamers hung in a twisted fashion while secured at both ends will serve as a visual deterrent from an area as well.
If eggs or infants are present the nest must be left alone. Almost all species of songbirds and migratory waterfowl are protected by federal law under the United States Fish & Wildlife Service. The average egg incubation period for songbirds is about two weeks however each species is different. Luckily songbirds are very quick to grow up, most fledge and leave the nest about two weeks after hatching, proving to be a short term inconvenience. After the babies have left, the nest can be removed and prevention techniques implemented to stop future nesting.
While rearing their young some birds may dive-bomb human “intruders”. This behavior is meant to frighten you away, and often it is frightening, but the birds will rarely actually make contact with you. Due to their small size an impact would more likely result in injury to the bird, it would be extremely unlikely for a human to get injured. A person can always wear a thick coat and a hat for additional protection if one feels necessary.
Ducks and geese can pose a slightly increased inconvenience as the incubation period for their eggs is about 25-30 days however after the babies have hatched the mother will lead her young to a nearby water source and not return to the nest.
If a bird has nested inside an air vent the same methods should be followed. A screen placed over the vent slats will prevent future usage.