Cannibal mouse

Question
Hi, I had two white male mice for nearly two years in a cage together. They ate and slept together. One died and the other had eaten her head???? Is this normal behavior?. They were well fed.

Answer
Hi Robert,

I am very sorry for your loss.  Mice cannibalize for a variety of reasons, but in this case it sounds like he was trying to get rid of the body.  Unfortunately, as gross as it seems, it is very common in rodents for eating other mice to start from the head down.  It is possible that this is out of mercy - if the mouse is still alive but dying, the other will have killed it before it continues eating, so he will not feel any more pain.  Another possibility is that it is simply the most efficient.  However you look at it - this is a very common occurrence, especially in male rodents, and serves to keep from wasting any nutrients in the natural environment.

Unfortunately, as natural or normal as it is, it can also make the survivor ill, so it is important that you keep an eye on his health in the coming week.  Not only can eating a mouse who died from unknown causes risk making the survivor sick, too, but he will also have a lowered immune system due to natural grief that he will experience at the loss of his buddy.  He will be relying on you more than usual for compassion and friendship, so try to give him a little extra time and watch him closely.  It would also be a good idea at this point to give the cage a good cleaning and sanitizing, since the cause of death for his friend was unknown.

Best wishes, and I am so sorry again to hear about your loss,
-Tam