How many mice are born at one time? - briefly
A typical mouse litter comprises five to twelve offspring, with the average size ranging from six to eight pups.
How many mice are born at one time? - in detail
Mice typically produce litters ranging from three to fourteen offspring, with the most common size falling between five and eight. The exact number per birth depends on species, age, nutrition, and environmental conditions.
Key factors influencing litter size:
- Species: House mouse (Mus musculus) averages six to eight pups; other species such as the deer mouse (Peromyscus maniculatus) often have slightly smaller litters.
- Maternal age: Young females (first estrus) may deliver fewer pups, while prime‑age females reach peak productivity.
- Nutrition: Adequate protein and energy intake correlate with larger litters; scarcity reduces offspring numbers.
- Season and temperature: Warmer months and longer daylight periods generally promote higher reproductive output.
- Genetic lines: Laboratory strains selected for high fertility can produce up to fourteen pups, whereas wild populations rarely exceed ten.
Gestation lasts approximately 19–21 days. After birth, pups are altricial, blind and hairless, gaining independence around three weeks. Females can become pregnant again within 24 hours of delivering a litter, allowing multiple births per year. In optimal conditions, a single female may generate six to eight litters annually, resulting in a potential population increase of several hundred individuals from one founder.
Extreme cases reported in controlled environments include litters of fifteen pups, but such occurrences are rare and often accompanied by increased mortality due to limited maternal resources.