Trimming hedges only once a decade a boon for bats

HEDGEROWS should be left unkempt for up to 10 years to help the bat population, researchers have suggested.

A study by the University of Bristol and the Bat Conservation Society found that some of Britain’s rarest species – the greater horseshoe, lesser horseshoe and types of long-eared bat – were found in greater numbers if hedges were left untrimmed, as were their insect prey.

Under Agri-environment Schemes (AESS) run by the Department of Agriculture, Environment and Rural Affairs, hedgerows in the countryside should be trimmed only one year in three unless permission is sought from the local council.

In the study, scientists monitored 64 hedges in various states of trim, and surveyed the wildlife they found in and around them over the summer of 2016.

They found that insect and bat species richness significantly increased with the time since last trimming. Taller hedgerows have more space for bat and insect life, and leaving them untrimmed creates a complex branch structure that is perfect for wildlife.

Researcher Jérémy Froidevaux said: “While the less severe trimming regime prescribed by previous and current AESS in England encourages farmers to trim hedgerows only one year in three, our study largely supports the longer term benefits of nontrimming on bats and their insect prey.

“Keeping some hedgerows untrimmed for up to 10 years would enhance bat species richness and insect family diversity.”

But the National Farmers’ Union disagreed. An NFU spokesman said that many farmers were in voluntary AESS that already helped deliver an array of environmental benefits, including increased wildlife.