In the United Kingdom beholds the RSPB's Dee Estuary nature reserve where in 2015, they started to discover mice nests everywhere! The Harvest Mouse, England's smallest rodent, weighs an average of only 0.176 ounces or 5 grams! It is also the only British mammal to build nests above ground in tall grasses. The team created a way to provide more homes for their 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.” The RSPB got in touch with local tennis clubs around the area to deliver the tennis balls, around 35 of them! They then drilled holes in them and put them throughout the nature reserve. This allows a safe home from predators as well as weather conditions and also will allow the harvest mice numbers to be closely monitored.