Ah, cannibal rat mommies. I have a litter right now that, the individuals, are just around 2 inches long (not counting tails.) Their mother was viciously eating her babies; I watched her rip one apart before my eyes. I left her in for a few days because the babies are, well, too small to be weaned really, but the carnage went on. Once half the litter was dead, I had to do something, and that evil wench is now in rattie heaven (or hell, lol!) Now what I am doing is, giving them a low-hung water bottle and moistened lab blocks for food. They ate it all overnight and appear to be doing very well so far; if I had left the mother in there, they would probably all be dead now.
I never have this happen; I have about ten regular breeding females and none of the others ever did this. Any ideas why she did? The babies appear healthy and active, and don't look sick or deformed.