Harvest mouse Micromys minutus, adult on wheat, Hertfordshire

Houses for harvest mice

Tennis balls provide perfect penthouses for harvest mice.

Providing homes for harvest mice

You might not think there’s much to celebrate about a grubby old tennis ball, but these seemingly uninspiring objects are being put to use in an unusual way by one of our country’s cutest critters.

In autumn 2015, wardens at the RSPB’s Dee Estuary nature reserve discovered an empty harvest mouse nest, alerting the team that these tiny creatures – not usually found so far north – had moved into their Cheshire site. Since then, the team have come up with a creative way of providing more homes for their resident rodents: by using old tennis balls.

Alasdair Grubb, warden at Dee Estuary nature reserve, said: “Sadly harvest mice numbers are falling in the UK due to changing farming practices and other pressures on our countryside, so we were delighted to discover they had made a home at Burton Mere Wetlands and were eager to find out how many and whereabouts they were living.”

Game, set, match!

The RSPB got in touch with a local tennis club to help deliver more of these unusual homes which, as well as an excellent recycling solution, will also allow harvest mice numbers to be more closely monitored.

Alasdair continued: “Tennis balls might seem like an odd solution, but it’s actually a trick that’s been used with balls from Wimbledon for years. So, I contacted the tennis section at Neston Cricket Club and enquired if they would consider donating any of their used balls.

“The club coach, Dan Stickland, was more than happy to help and provided 35 old tennis balls for me to drill a hole in and put around the reserve in suitable locations; which means next summer I’ll be able to revisit each tennis ball and see whether it has been used as a nest.

“As well as allowing us a means of surveying the numbers, the tennis balls also protect the mice from predation and bad weather, and provide extra homes by giving them chance to nest in areas where there might be ample food, but not quite the right conditions.”

Did you know?

  • England’s smallest rodent, the harvest mouse weighs an average of five grams – that’s about five paperclips.
  • It is the only British mammal to build nests of woven grass above ground in tall grasses, reeds, cereals or hedgerows.
  • You’ll be lucky to see one, however. Not only are they very secretive, harvest mice as a species are in decline due to changes to habitat and agricultural methods.