Rand- 16 bits only????

I've started working on evolving constraints using verlet physics, and set up the seed configurations code. I'm using one bit per constraint, representing whether or not the constraint exists. I decided to be clever and fit it all into an int, but rand appears to only create 16 bits. sure, the bits cover a wide range, all the way to the max, but it only generates 16 bits. This is what I get in the debugger:
(displaying the bits)

0100010101001010100000000000000
0010001010111011100000000000000
0100010111101110100000000000000

and so on and so on.....

Any ideas/ fixes