'Squashed poo' a sign of water voles' success
Signs suggest the water vole population on the Hogsmill River in Surrey has been reestablished.
Pia Trevelyan-Ashby, an urban rewilding officer, expressed excitement upon discovering water vole droppings, noting that they "are the best way of getting an indication of how the rodent's population is doing". One year ago, South East Rivers Trust and Citizen Zoo introduced 42 water voles into the Hogsmill River in Surrey. The population appears to be thriving, with signs of survival and growth.
South East Rivers Trust's catchment officer, Laura Nee, explained that mink prey on water voles daily. Removing a mink from the ecosystem protects various species, including water voles. The UK has lost nearly 90% of its water vole population since the 1970s.
To monitor the population, Citizen Zoo has set up camera traps and latrine rafts where water voles excrete. Trevelyan-Ashby spends an abnormal amount of time searching for droppings, which indicate the population's health. Recent surveys confirmed water voles in both upstream and downstream areas of the original release site.
Burrows in the riverbank are another sign of water vole activity. Trevelyan-Ashby pointed out squashed poo as proof of active burrows. Once common in the Hogsmill River catchment, water voles were locally extinct until a release in 2025 marked their return to the county after more than two decades. The presence of water voles suggests a healthier river with adequate vegetation and natural bank erosion.
Written by urgent.news from BBC Science's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
