A survey of bat activity on the Thames last week found that bats are much happier in Richmond than Kingston - where too much light is driving the furry mammals away.

The survey, commissioned by the Environment Agency, was carried out by bat workers Alison Fure and Jackie Wedd and compared bat levels in the dead of night in Richmond on August 29 with previous data gathered in Kingston on August 18.

Ms Fure said that light levels on Richmond Bridge stood at 6.7 lux compared to a massive 31 lux on Kingston Bridge - due to better lighting which directs glare away from the river.

Bats, a protected species, are usually only found inhabiting areas with levels of zero to four lux.

An increase in light levels has seen rarer, dark-loving bat species such as the Natterer diminish, while more light-tolerant Pipistrelles are more abundant.

Ms Fure criticised the unnecessary and expensive lighting in Kingston and said cover from glaring lights is crucial for the mammals.

She found plenty of the creatures living on the dark Thames islands near Richmond, describing these river santuaries as "stuffed with bats", and added that on Stevens Ait, an island closer to Kingston, deforestation has driven the bats away and added to the light pollution threat.

She said that if light pollution is not tackled soon, bats will abandon the Thames altogether.

"Land owners should consider how they light their land and property. The less light used the better," she said.