BAT populations are booming along a stretch of Lincolnshire river – to the delight of environmental groups.

The River Witham is the perfect place for bats to thrive and the Environment Agency said the area should be protected to keep the numbers up.

Plummeting numbers mean all bat species are protected by law and the 1,430 recordings along the stretch of Witham surveyed have been heralded as vital to the continued survival of the winged mammal.

The recordings do not represent the number of bats, but they do show a lot of activity along the river.

Lincolnshire Bat Group spokesman Annette Faulkner said: "I think this emphasises the fact rivers and all waterways are immensely important to bats.

"The findings do not surprise me because bats live off insects that live near the water.

"I'm very pleased they have found some Noctule bats as they are in decline in the south and middle of the county."

Ruth Snelson, of the Environment Agency's Fisheries, Recreation And Biodiversity Team, said: "These results show the River Witham is an important area for feeding and provides a corridor that links urban areas such as Lincoln and Boston with the wider countryside.

"It is important habitats such as this are protected because intensive farming and the use of pesticides have led to a reduction in the insects bats rely on as their only source of food.

"The Environment Agency's work to improve water quality in our rivers and reduce the impact of farming and industry will help ensure the River Witham continues to support a healthy bat population."

Common Pipistrelle, Soprano Pipistrelle and Daubenton's bat were all found in impressive numbers and a fourth species, known as Noctule bats, were found in some areas.

Two surveys were carried out on the Witham, one between Bardney Lock and Lincoln and another between Bardney Lock and Boston.

They were done using an Anabat detector, which records the sonar echolocation calls of the creatures.

Rachel Shaw, of the Lincolnshire Wildlife Trust, said: "It is very encouraging to see these species are thriving in Lincolnshire.

"All bat species have struggled with loss of habitat and reduced numbers so it is great news they're doing well along the river banks."

Another survey will be carried out this autumn to monitor any changes in the population.

Protection laws mean bat roosts cannot be disturbed at anytime of year. If you have bats in your roof space you can still have work done, but should contact Natural England for advice first.