"Bats use a lot of different types of sounds, from singing to each other to find a mate and to using echoes from their tweets to find their way around, " explained Kate Jones, joint University College of London (UCL) and Zoological Society of London (ZSL) chairwoman of ecology and biology.

BBC: Website calls on people to become 'bat detectives'

Last year the pandas were introduced to each other several times but did not mate.

BBC: Edinburgh Zoo's pandas may be ready to mate

These strains do not ordinarily mate with each other, and their hybrid offspring tend to show abnormal growth.

ECONOMIST: Genes are not all there is to heredity