How long is the gestation period of street rats? - briefly
Street rats have a gestation lasting roughly three weeks, typically 21‑23 days.
How long is the gestation period of street rats? - in detail
The pregnancy of urban Norway rats typically lasts between 21 and 23 days. This interval can shift slightly depending on temperature, nutrition, and stress levels. Warmer conditions tend to shorten the period by a day or two, while poor food availability may extend it.
Embryonic development proceeds rapidly. By day 5, organogenesis is underway; by day 10, fetal limbs are distinguishable; by day 15, the pups acquire fur and begin to move within the uterus. The final three days involve rapid growth and preparation for birth.
Key variables that influence the length of gestation include:
- Ambient temperature: 20‑30 °C accelerates development; lower temperatures delay it.
- Maternal diet: high protein intake shortens gestation; caloric restriction lengthens it.
- Parasitic load: heavy infestations may prolong pregnancy.
- Social environment: high density and frequent disturbances can increase stress hormones, modestly extending the gestation period.
Litter size does not markedly affect duration; litters of 6‑12 pups follow the same 21‑23‑day schedule. After delivery, females become receptive again within 24‑48 hours, allowing multiple litters each year, especially in temperate urban settings where breeding can occur year‑round.