How many pups does a mouse have? - briefly
A mouse usually produces a litter of 5–12 young, with the average size being about 6–8. The exact number varies with species, health, and environmental conditions.
How many pups does a mouse have? - in detail
Mice usually produce between three and fourteen young per reproductive event, with the average for the common house mouse (Mus musculus) falling around six to eight. The exact count varies according to species, age, health, and environmental conditions.
- Species differences: Small-field mice (Apodemus species) often have litters of four to six, while deer mice (Peromyscus maniculatus) may reach up to twelve.
- Maternal age: First‑time breeders tend to have smaller litters (three to five), whereas mature females can achieve the upper range.
- Nutrition and stress: Adequate protein and low stress levels increase litter size; poor diet or overcrowding reduces it.
- Seasonal effects: In temperate zones, breeding peaks in spring and summer, when larger litters are more common.
Gestation lasts 19‑21 days, after which the newborns are altricial—blind, hairless, and dependent on maternal care. Litter size directly influences the mother’s ability to nurse; excessively large litters may result in lower survival rates for some pups. Consequently, natural selection balances reproductive output with offspring viability.