Broody chuck

Depending on the breed.  Some will do it more then others. 

But yes its totally natural (as far as a chicken goes!)

They can starve them selves when they go broody so your best to break her as soon as you can.

Try locking her out of the coop if you can.  If your unsure shout up there are plenty of "how to guides" kicking about on here - or just search "breaking a broody" on the forum.

Broodiness has reached epidemic proportions in mt coop.    Each of my six pullets has had a turn at being broody in the last few weeks.  The first five I just chucked them off the nest whenever I saw signs of broodiness and they soon gave up. 

Unfortunately with #6 I wa away for a few days and when I came home I found her determinedly sitting on the nest.  Kicking her off the nest did no good, nor did locking her out of the coop (she just paced up and down all day, fretting).  I locked her in a wire-bottom cage for two days but it made no difference.

In the end I took away the nest boxes completely for a day.  All the girls were terrribly distressed - one laid her egg on the floor, and another on the shelf where the nest boxes used to be.  It rolled off and broke.   Thinking I had messed things up completely, I put the nest boxes back the following morning, and my broody girl wasn't broody any more!  Hooray!  It was all very stressful though, and I wish they would stop it!