Mouse breeding advice

Question
I would like a pet store that sells both male and female mice; do you know of any? Every time I go to a store I see "Male mice" or "female mice" only, never one that has both cages for them. I ask this because I am hoping to breed once to get the experience of raising mice.

Answer
Dear Oliver,

The best place to get mice, if you want to breed them, is from a private breeder. Pet store mice are not bred for longevity, and if they use the same mice as feeders, they are often not even bred for health. Also if one mouse in the cage gets sick, they can all get sick and you can bring home a sick mouse. If you do go to a pet store, be very sure that your mouse is healthy: It should be running around, bright-eyed, slender with no posture problems, with neat fur, and have no visible scabs, fluids, etc.

But the first thing you need to do is read about breeding mice. Mice will certainly propagate without your assistance, but the problem is how to keep the numbers down afterwards. It is hard to adopt out male mice because males have to live alone (because they will fight to the death). Females can all live together.

Let's take an example of mouse husbandry gone awry. Say you start with a pair of mice on day 1. In three weeks you will have a litter, generation A. A litter can be anywhere from 1 to 18 babies in my experience alone. So let's say every litter is ten. We'll assume five of each sex. At day 21 you have 12 mice. The babies are old enough to mate as young as 4 1/2 weeks, but this will be easier if we assume six weeks. Because mice mate immediately after birth (which is why you must separate the pair before the birth), on day 42, there will be a second litter, generation B. That will make another ten, totaling 22 mice. The original pair mates again. On day 63, the original pair gives you another litter, generation C. You now have 32 mice. On that day, the first litter is ready to mate. So that will be 5 more breeding pairs. Thus on day 84, you will get the usual 10 with generation D, plus another 50 babies from the first litter, making 92 mice. At that point, generation B is ready to mate. Generation A will also continue to mate. On day 105, you will get 11 new litters of ten mice each. Let me try this more numerically:

0:  Gen 0 : 2 mice
21:  Gen A:  2 + 10
42:  Gen B : 2 + 20
63:  Gen C: 2 + 30
84:  Gen D: 2 + 40 + 10*5
105: Gen E: 2 + 50 + 10*5 + 10*5*5
126: Gen F: 2 + 60 + 10*5 + 10*5*5 + 10*5*5 + 10*5*5*5...

Or something like that. That's 4 months and you have over a four thousand mice.

Remember, since half are boys, you will need at least 2,000 cages!

That's to put it in perspective.

So, my advice is:

1. Read about breeding mice
2. Get two healthy mice from a private mouse breeder. This isn't as expensive as you think. Most breeders breed for fun and not profit.
3. Separate the pair after the female is 2 weeks pregnant
4. Find homes for the boys as soon as you know their sex (after a week)
5. Keep the pair separated and the females all together. Rehome the males.
6. Don't breed again until you are sure you have good homes for the all babies.

I don't know where you are but I may be able to help you to find a good private mouse breeder. You can also try one of the national mouse sites:

American Fancy Rat and Mouse Association:
http://www.afrma.org/

Rat and Mouse Club of America
http://www.rmca.org/

North American Rat and Mouse Club, Inc
http://narmci.8k.com/index.html

As for pet stores, I'm surprised you couldn't find one store with both sexes, though it is good that they have them separated. I haven't bought from a pet store in decades, but the Petco where I live has mice of both sexes.

Best of luck! Have fun with the babies!

squeaks n giggles,

Natasha