When are rats born? - briefly
Rats are usually born after a gestation period of about 21‑23 days. Litters commonly consist of 6 to 12 offspring.
When are rats born? - in detail
Rats reach sexual maturity at approximately 5–6 weeks for females and 6–8 weeks for males. After a single mating event, the female undergoes a gestation period of 21–23 days, after which the litter is delivered. The timing of parturition is not tied to a specific season; breeding can occur throughout the year in controlled environments, while wild populations may show peaks in spring and autumn when food availability rises.
Key factors influencing birth timing:
- Estrous cycle length: 4–5 days, allowing frequent conception opportunities.
- Light exposure: longer daylight periods can accelerate reproductive activity in some species.
- Nutritional status: adequate protein and energy intake support regular ovulation and successful gestation.
Typical litter characteristics:
- Size: 6–12 pups on average; extremes range from 1 to 20.
- Birth time: primarily during the early night hours, aligning with the species’ nocturnal nature.
- Neonatal development: pups are altricial, opening eyes around day 14 and weaning by week 3–4.
In laboratory settings, breeding colonies are often managed to produce a new litter every 3–4 weeks, ensuring a steady supply of offspring for research. Wild rats, however, may experience longer intervals between litters due to environmental pressures and predation risk.