Where do water rats spend the winter? - briefly
During winter, water rats shelter in insulated burrows or nests constructed in riverbanks, under rocks, or within dense aquatic vegetation. These refuges keep them dry and protected while they continue to forage in the water.
Where do water rats spend the winter? - in detail
Water rats remain active throughout the cold months, relying on specific environmental features to survive winter conditions. They favour habitats that provide both shelter and access to unfrozen water, allowing continued foraging and protection from predators.
Key winter refuges include:
- Burrows dug into riverbanks, stream margins, or lake shores where the substrate remains moist and insulated.
- Dense riparian vegetation, such as reeds, cattails, and submerged root systems, which offers concealment and a steady supply of aquatic invertebrates.
- Ice‑free sections of ponds and slow‑moving streams, often found in shallow areas or where groundwater inflow prevents surface freezing.
- Anthropogenic structures like drainage culverts, levee crevices, and abandoned fishing nets that retain water and create microhabitats insulated from extreme temperatures.
Physiological adjustments support these choices. A denser undercoat and increased body fat improve thermal regulation, while a modest reduction in metabolic rate conserves energy when food is scarce. Water rats also shift their diet toward more readily available prey, such as crustaceans and small fish that remain active under ice.
Geographically, populations in temperate regions of southern Australia and New Zealand retreat to the aforementioned microhabitats, whereas individuals in milder coastal zones may remain on open banks throughout winter. In all cases, the combination of secure burrowing sites, persistent water flow, and protective vegetation determines where these semi‑aquatic mammals endure the cold season.