Gerbils have some nasty habits. WHen I worked at a pet store, my friend/co-worker and I took care of small animals. One female gerbil was like that, she would eat the limbs off her offspring slowly. They were still nrusing so to remove them would kill them, so everyday we would see babies missing more and more body parts. Finally, they started dying off. When there was only one left, it was old enough to be seperated from her and my friend bought it (yeah, the owner of the store woulnd't even give it to her fro free, and the thing was missing a rear leg!) Tripod lived out his days happily and was spoiled pretty well.
Gerbils (and hamsters...and mice) are SICK!