The original rodent whisperer, the Pied Piper, employed a low-tech method: a wooden recorder has a much lower environmental footprint than your average rodenticide.
Rats and mice are not covered by the International Humane Trapping Standards. If they were, glue traps or boards, peddled by just about every hardware store despite criticism from the RSPCA, would presumably be outlawed. Rodents run on to the glue-covered board and are stuck fast. In a slow and agonising death they are liable to chew their own legs off. Then there are poisons. Rodenticides are usually anticoagulants causing the mouse to haemorrhage, leading to a protracted death as it crawls off to die under the floorboards, or similar.
The old Tom and Jerry-style snap traps are also a grim prospect. But your mice visitors obviously have to go. Rodents carry 35 zoonotic diseases (those capable of transferring from animal to human) and breeding rates are startling: one mouse can produce 2,000 progeny in a single year.
There are humane traps such as the Trap Man Humane Mouse Trap (£18, wigglywigglers.co.uk), which house the unwanted pest - some have extra ventilation, and facilities to feed and water the captive. You must check these every six hours (if you are using humane traps outside to catch grey squirrels, you are legally obliged to check them every day), otherwise the mouse might die from starvation. The idea is then to release the mouse away from your home. Apocryphal tales suggest that they have a knack of finding their way back, which is why many people drive to a park a few miles away. But how ethical is this? Unless supplied with a nest, food, family and seemingly a mobile phone, all the evidence suggests a domestic house mouse will be finished off pretty quickly in this real-world environment.
Which is why Peta (People for the Ethical Treatment of Animals) recommends a mousetrap that actually kills the animal, and gave the Radar (Rodent Activated Detection and Riddance device) an award last year. This is allegedly the world's smartest mouse trap: when a mouse trips it, the doors close and a tiny canister releases carbon dioxide. In 10 seconds the mouse is out cold, in 60 it's dead. The device then sends an email to a pest controller - all 'without any toxins going into the environment', boasts Rentokil (0800 917 1989).
There are other professional helpers who focus solely on humane methods, including John Bryant from Humane Urban Wildlife Deterrence (jbryant.co.uk) or humanegroup.com. You can also experiment with sonic waves. A Victor device (izola.co.uk, 0800 542 5307) emits between 32 and 62 kilohertz of ultrasonic sound. The idea is that the mice find this din (inaudible to humans) so irritating that they soon move out.
Once they've gone, revert to a low-tech method to keep them out. Even accounting for its eco pawprint, a cat padding around the house on mouse watch should prove a suitable deterrent.