Can deer mouse and house mouse mate?

Question
Hi there,

We rescued a baby Deer Mouse a year ago in February.  She (Daisy) was less than 2 weeks old, eyes still closed.  She became very tame and until recently she seemed happy enough alone in her cage and enjoyed the occasional roll in her ball throughout the house.  About a month ago, she chewed through the plastic cage edges until she could slip through between the bars.  She found us a day later and returned to her cage.  Since then, she has left and returned twice.  We most recently had to trap her to get her back again since we knew she was running around the house.  Now that she's back, we're looking to rehome her to an aquarium tank.  We just want her to be happy, especially now that she's had a taste of freedom.  Luckily, she hasn't found her way outside.  
Two weeks ago we discovered a House Mouse (guessing as he has much smaller eyes)in our basement and that night he opened both eyes.  He's (Benjamin) off of the kitty milk and now eats fruits, grains, etc.  He's in his own cage but I was hoping since he is so young and a different species than the older female Deer Mouse, that we could possibly cage them together.  Is this possible?  
Possibly this is a question for Tamarah but we are looking to figure out what to do sooner than later, hopefully.  
THANK YOU!!!

Answer
Dear Tracey,

Deer mice and house mice can't mate. The reason pet/fancy mice and house mice can mate is that pet mice are descendants of house mice. I think it is a great idea to put them together-- but watch super carefully. They will not recognize each other's smell as a normal mouse, but lots of species of all kinds cohabit, so it certainly is likely to work. Wait till the baby is 4 weeks old (eyes opened for two weeks). Introduce them on very neutral territory first-- for instance the bathtub. First dab each mouse on the rump and neck with REAL vanilla essence. The fake stuff doesn't work. That way they will smell alike. Keep your hands near them just in case. Afterwards I would recommend putting the adult in the cage which smells nicely of the baby mouse. That way Benjamin isn't encroaching on Daisy's territory, and Daisy is the visitor, for a short amount of time (it won't take long for Daisy to take over).  You can continue with the vanilla essence periodically for a day or two if you see any aggression.

When mice meet, there is usually a lot of chasing and squeaking. With a baby, this can end (recurrently) in a situation where the baby is on its hind legs baring its belly to the adult. I believe the baby is giving the adult the chance to kill it-- thus putting itself at the adult's mercy-- which the adult generally respects.

When should you give up and decide it won't work? Only if there is blood; if the baby becomes depressed and doesn't want to move around much; or if Daisy isn't letting Benjamin near the food or nest.

You are right to put them in a cage they can't escape from. Even though she has known the world and wants more space, it is too dangerous for a mouse to be out in the house. And of course there is always the chewing and mess she will make. Do get her a 30 gallon aquarium. That is a good amount of space for two mice. She might resent it for a little while but hopefully she will get used to it. I know what it is like to have a mouse taste freedom and get frustrated. After my mouse Brandy escaped from an unlocked door and ran through the apartment, she was hooked. When I caught her, she even jumped from my shoulder to get back down. She spent the next two days solid trying to chew the bars of the cage. But when I got her a 4-story converted bird cage (and six wheels for 5 mice) she was finally happy. I hope Daisy can settle down enough to be happy!

Have fun with your little creatures. I'd love to see a picture of the two of them!

squeaks n giggles,

Natasha
<:3  )--~

--yeah, Tamarah is on vacation. The poor woman took over for me for two months while I dealt with a family situation, and she was exhausted! I'm hoping she'll take a long vacation.