Hundreds of animals spawning near world edited places

Hi, recently i have been having problems with world edit. I have copy and pasted some buildings with world edit around my world, but the problem is, is that around these pasted areas, hundreds of animals have been spawning close to them.

I would like to know if this is happening to anyone else or if it is just me. Also if anyone has a solution to this, i would be grateful (I have used the killall command, but eventually they all spawn back).

Thanks