unexpected babies

Question
Hi Tamarah,
We discovered to our surprise a week ago that our new pet fancy mouse had a litter of babies.  When we found them, they had fur but still had their eyes closed.  They are now open and moving around a little bit but not out of their igloo nest.  I am scared to touch them due to warnings from a friend of the mom abandoning them.  I have no idea how to judge how old they are and I am scared that they could reproduce again.  My question is how can I tell how old they are and when can they be handled?

Answer
Hi Christa,

Congratulations on your new litter, even if it was a surprise!  You can guess at their ages using this picture:  http://jaxmice.jax.org/images/literature/pupsposter-large.jpg  If they're too big to tell with the chart now, you can kind of guess around how many days old they were when you first noticed them and count from there.

You should separate the boys from the girls before they are five weeks old, but not until you have seen one or more of them using the water bottle (usually around 3-4 weeks, do not separate before 21 days old).  They usually learn how to eat solid foods while they are still nursing, then will wean themselves once they start getting their hydration on their own.  You can help them out by lowering the water bottle a tad in the cage so everyone can reach it.  The earliest they could reproduce is around 5 weeks, so take the boys out by then, using this as a reference to help you sex them:  http://www.thefunmouse.com/info/sexing.cfm  Their genders can be hard to figure out at first, but if you keep notes of which ones you think are which genders you can check them several times before you actually separate them to be sure.  Once you do separate them, be sure you watch the males closely to make sure they all stay in good health - sometimes as the boys mature they become aggressive toward one another.

As far as handling - you can handle them at any point once they have fur.  Sometimes you can handle them sooner, but since the mom is new and you don't know how she'll handle that, it's best to let them grow coats first (these hold in their own personal scent, so it's harder to confuse mom).  To handle the pups, first wash your hands and wait until mom is off her nest, then pick her up and place her in another cage out of sight from her babies.  If she runs back to her nest before you can get her, leave her alone for a little bit and try again later.  You can play with mom a bit before locking her away to get her scent on your hands, if you like.  Then pick up a little bedding and rub it on your hands to hide any leftover smells, then you can tenderly pick up the pups one by one.  Only handle one at a time, because some can be troublemakers and hop out of your hands or waddle right off, and you'll need to devote your focus to each one.  Keep your hands in the cage or low to the ground in a mouse-safe area to prevent injuries in case they hop (mice frequently enter hopper stage around 2-3 weeks old and bounce around like popcorn).  You can reduce hopping by not touching them from above while holding them - touch them from the side or below to keep from spooking them.  The more you handle them, the sweeter and calmer they'll be when they grow up.  After the first time you play with them, keep an eye on momma's reaction when you put her back in the cage.  Make sure all pups are back in the nest before you replace her, give her a treat to calm  her  nerves, and listen for squeaks or trouble for the next ten minutes or so.  Different moms have different personalities, so there is no predicting how she'll react until you try.  However, every day they grow older increases their chance at survival, and I've never had a mom abandon or injure her pups after about a week old.

Congrats again, and have fun with your new babies!  Let me know if you have any more questions.  :)

-Tam