Scientists based at the Chinese Academy of Sciences and University of California investigated the behaviour of Babina dauchina, better known as the Emei music frog because of its distinctive banjo-like call. The male frogs build burrows along the edges of ponds to provide a suitable location for mating, laying eggs and rearing tadpoles, and the researchers noticed that they seem to make different calls from inside and outside the burrows.
By analysing the acoustic properties of the calls and examining the way that female frogs react to them, the researchers discovered that the male frogs actually not only advertise whether they have a burrow or not, but also its physical characteristics such as the size of its entrance and its depth. Female music frogs are then able to choose the male with the most desirable real estate, without having to go through the time-consuming business of waiting to be shown round.
As the authors state, “males of this species faithfully advertise whether or not they possess a nest to potential mates by vocal communication...These results suggest that females are able to evaluate the resources of their potential mates and select against males lacking such resources, mainly depending on advertising calls.”