Breeding an animal is never a decision to be taken lightly and it is always best to have had a few years experience of them as pets before embarking on it. There are many things you need to consider; one vital aspect of breeding rodents knowledge of genetics and ethics.
Check your local rescues, as if they have rodents needing homes in your area you must think very carefully and have a good reason for adding more. You must have potential homes lined up as if you supply a pet shop with your rodent's offspring you stand a high risk of them ending up as a meal for a reptile.
For more details, see our article on when to breed rodents - ethics and care.
Breeding and Gestation
Breeding pairs have more stability than trios as the latter can be more volatile however some European keepers advocate keeping them in larger colonies for better breeding success although unless the habitat is large enough it is likely only the alpha pair will breed. Before breeding try asking other keepers in Exotic Forums what setup they use.
Egg food is a good addition to the diet of a breeding pair of Zebra mice and a constant source of protein should be available.
Females are sexually mature at around 4 months, and males at 7 weeks. The female remains in season for 3-5 days and has a gestation of 21 days. Some keepers have had success with placing the female in with a male just during the time she is in season, however this will vary according to temperament as some Zebra Mice can be extremely aggressive. Fighting can occur during mating and animals should be separated if blood is drawn. Zebra Mice females should not be bred after the age of 14 months.
The father should be left in with the mother since re-introductions are extremely difficult, so it is advisable to have two nests so the male has somewhere to sleep if the female forces him out of the birthing nest.
A gap between litters should not be longer than 3 months, as this could lead to birthing problems. However your female Zebra mouse will need 1-2 months of rest after every 3 litters since these can be occurring every 3 weeks. Sometimes your Zebra mouse may delay implantation if her body needs time to recover after a litter.
Litters
Litter size can be anything from 1-12 with an average size of 2-5. When born pups have been likened to mint humbugs due to the prominent striping. Like a lot of rodents, mum will come into heat soon after giving birth.
Eyes open between day 6-8 and they begin to wean at around 14 days. When handling pups, ensure you place them back in the nest after handling even if they are mobile. The pups will become full-sized at 6 months of age.
Sexing
Male pups should be separated out by 8-10 weeks of age although females can stay with their parents until around 4 months providing your habitat is large enough.
You can make your first attempt at sexing at around 4 days, but this must be repeated as it can be easy to make mistakes early on. A male zebra mouse has a larger distance between the genitals and the anus than the female, and should have a darker pigmented patch of skin at the base of the tail where testes will be. Nipples can be seen on the girls from around 5 days just as belly fur is beginning to grow.
For a photo guide to sexing see Barbary Striped Grass Mice guide to sexing.
Mutations
There are currently two colour mutations in Zebra mice, a banded Zebra mouse that is born with white "spot" and silver zebra mice that are born with normal colouring and then develop the white spot as they get older. These variations are sometimes called banded, or pied - see example photo.
Introductions
Zebra mice can be a very aggressive species and it is very hard to introduce two adult mice. Introductions to make unrelated pairs for breeding are best done once pups have weaned and are ready to leave mum and can be done directly. For lone adults a split-cage introduction can sometimes match them up.