The Squatting Bird

This started either a couple or a few weeks ago.  You know those small lights right next to the top of your front door that is there to, you know, illuminate the front door?  Well, on the left one, a bird has built a nest.

I don't get it.  First of all, the, uh, bracket that connects the light apparatus with the vinyl siding isn't big at all.  But this bird decided that it was big enough to gather sticks and grass and set up a home right there.  Second of all, it is always startled whenever one of us opens the front door.  I step out, open the screen door, and I'm get startled (I keep forgetting there's a squatting bird that has built a tiny nest behind the door light) as I see that bird furtively fly away.  And though I have not been able to accurately track its trajectory, it seems as if it has another nest in a nearby tree in the neighbor's yard.  Oh, so this bird isn't a squatter so much as this nest next to our door is a second home to him, and he sees fit to travel between his main place and his, uh, "cabin nest" whenever he gets scared.  And by the way, this bird might in fact have a third home; when I approach the front door after coming home, it sees me and flies the other way, and it appears as though it goes up to another nest in another tree in another neighbor's yard.

Don't know how long this will last.  Not like I'm going to destroy the nest; that'd be rude.  But what happens when leaves start to bloom on the trees which serve as the homes for this bird's, uh, two homes?  Those nests can't stay, can they?  And if they can't stay, well, that means that this bird is moving in right next to our front door for the whole year now.  Right?