How do you get birds that are living in your house to leave?

So apparently a bird decided to go down our chimney and made a nest in the walls of my family's house. For the past few weeks we've been hearing the birds chirping non-stop, but we're not sure how we're going to get them out without causing a big ruckus. We're kind of hoping that they'll just leave, but so far there's no luck. Any advice?