Gede: However, throw in a cat or a bird of prey, and you can see them taking flight and performing evasive manoeuvres in flock. It is quite curious.
Cats are used as a final host for a mind-altering parasite, Toxoplasma gondii (it can only reproduce in cats).
It uses rats/mice as an intermediary host, then alters their behaviour so the rat can get eaten and the parasite can enter the cat to reproduce.
There's a YouTube video where they placed two boxes at each end of the room.
One was sprayed in cat urine, the other in rat urine.
Two lots of rats were then released, infected and uninfected.
All the ones without the parasite ran straight for the box with rat urine and hid terrified.
All the ones with the parasite were seeking out the cat urine and smell.
Absolutely incredible that a tiny organism can do that.