How long do water rats live? - briefly
In natural habitats water rats typically survive 2–3 years, while individuals kept in captivity can reach up to about 5 years.
How long do water rats live? - in detail
Water rats (Hydromys spp., commonly the Australian rakali) typically reach 3–5 years in natural habitats. Individuals that avoid predators, have access to stable food supplies, and occupy high‑quality riparian environments may live up to 7 years, though such cases are rare.
In captive settings, where diet, veterinary care, and protection from predation are controlled, the average expectancy extends to 6–9 years. Exceptional specimens have been recorded at 11 years, reflecting optimal husbandry conditions.
Key factors influencing longevity include:
- Predation pressure – mammals, birds of prey, and introduced feral cats account for most premature deaths.
- Water quality – pollution and eutrophication reduce prey availability and increase disease risk.
- Nutrition – a diet rich in fish, crustaceans, and occasional amphibians supports robust health; deficiencies accelerate aging.
- Disease – parasitic infestations (e.g., helminths) and bacterial infections such as leptospirosis can curtail life span.
- Genetic variability – isolated populations may exhibit reduced vigor, affecting overall survival rates.
Reproductive effort also impacts lifespan. Females breed annually, producing 2–4 young after a 30‑day gestation. The energetic cost of lactation and territorial defense can shorten adult life, especially in resource‑limited environments.
Overall, water rats demonstrate a moderate lifespan relative to other semi‑aquatic rodents, with the longest survivals observed under protected, well‑managed conditions.