When do rats mate? - briefly
Rats reach sexual maturity at roughly 5–6 weeks and mate year‑round, with heightened activity during warmer periods. A female can become pregnant within 24–48 hours of estrus and may produce a new litter every 3–4 weeks.
When do rats mate? - in detail
Rats reach sexual maturity at 5–6 weeks for females and 6–8 weeks for males under standard laboratory conditions. Female rats exhibit an estrous cycle lasting approximately 4–5 days, divided into proestrus, estrus, metestrus, and diestrus. Ovulation occurs at the onset of estrus, and females are receptive to copulation only during this brief window, typically for 12–24 hours.
Mating behavior follows a predictable pattern:
- Estrus detection: Swelling of the vulva and a moist vaginal discharge signal the receptive phase.
- Courtship: Males approach the female, emit ultrasonic vocalizations, and perform olfactory investigation.
- Copulation: A single ejaculatory event lasts 3–5 seconds; females may receive multiple intromissions within the receptive period.
- Post‑copulatory interval: After successful mating, females enter a refractory phase lasting the remainder of the cycle, during which they are not sexually receptive.
Environmental factors such as photoperiod, temperature, and population density can shift the timing of the estrous cycle, but under controlled conditions the 4‑day rhythm remains stable. In breeding colonies, the majority of successful matings occur between 8 weeks and 6 months of age, after which fertility gradually declines.
In summary, rat reproduction is confined to a short, predictable receptive phase each 4‑day cycle, beginning at sexual maturity and persisting throughout the adult lifespan, with each estrus offering a limited 12–24‑hour window for successful copulation.