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Despite regularly changing their roost, bats will choose to lodge with the same social groups of 'friends' following each move, claims research. 

By tracking movements of bats in Oxfordshire woods, researchers discovered that different social groups roost in separate, though adjacent, parts of woodland.

The findings have important implications for conservation as bats may not be able to move to another area if a section of woodland is felled.

A study carried out over five years in Wytham Woods, Oxfordshire has found that bats like to stick together. This image shows a network analysis of how individual bats interact in social groups. Nearly 1,500 bats were fitted with small aluminium arm bands to make the findings

The research was carried out by scientists from the Centre for Ecology and Hydrology, the University of Exeter and the University of Oxford.

Experts concluded that the structure of bat social groups differs between two different, but closely-related, species living in the same woodland.

TRACKING THE MOVEMENT OF BATS 

Bats are pictured roosting together in Oxford

The study was carried out over a five-year period in Wytham Woods, Oxfordshire.

Nearly 1,500 bats were fitted with small aluminium arm bands, and four bats were tagged with lightweight radio-transmitters.

The radio tracking showed the bats changed roost site about once every two days.

Each social group was found to occupy a home patch in the wood.

Although the bat species occupied the same area of woodland, the home patches of the different social groups within the species did not overlap, suggesting that social groups may defend their roost areas. 

One species, called Natterer's bat (Myotis nattereri) forms mixed-sex social groups, while a second species, the Daubenton's bat (Myotis daubentonii), has largely separate male and female groups.

Dr Tom August from the Centre for Ecology and Hydrology, who conducted the study, said: 'When the first results came through it was a real eureka moment, I hadn't expected to see so many separate social groups in the woodland.'

The study was carried out over a five-year period in Wytham Woods, Oxfordshire.

Nearly 1,500 bats were fitted with small aluminium arm bands, and four bats were tagged with tiny lightweight radio-transmitters to enable them to be tracked.

The radio tracking showed that the bats changed roost site frequently - about once every two days.

Each social group was found to occupy a home patch in the wood.

Although the two bat species occupied the same area of woodland, the home patches of the different social groups within the species did not overlap, suggesting that social groups may defend their roost areas.

The relationships between bats in the same social groups were found to be enduring, in many cases lasting more than a year.

Dr Mathews from the University of Exeter who led the research team added: 'This work has really important practical implications for bat conservation.

The research at Wytham Woods (shown on map) was carried out by scientists from the Centre for Ecology and Hydrology, the University of Exeter and the University of Oxford

Experts concluded that the structure of bat social groups differs between two different, but closely-related species living in the same woodland. One species, called Natterer's bat (shown left), forms mixed-sex social groups, while a second species, the Daubenton's bat (right), has largely separate male and female groups.

'We now realise that although social groups of woodland bats 'move house' every few days, they remain within a very small geographical range.

'This means that even quite small-scale tree felling may destroy all the roosts potentially available to a group.'

The research has highlighted that the social networks of animals are poorly understood, but they are 'fundamentally important to processes ranging from information transfer to the spread of disease'.

Dr Matthews concluded: 'Just as some types of people are super-connected on Facebook, this work shows that in animal systems, two very closely related species living in the same habitat can have very different kinds of social network.'

The findings are published in the journal Plos One.