Researchers compared the mating calls of the tiny male tungara frogs living in Panama City's urban streets and those living in the nearby tropical forests.

Male tungara frogs, native to central and south America, use their distinctive mating calls to attract females.

The researchers from the Smithsonian Tropical Research Institute (STRI) said the frogs - dubbed the "acoustic equivalents of peacocks" - can add extra elements to their love songs to lure the females in.

Scientists played recordings of male tungara frog calls in urban and forest locations and monitored the number of approaching females, predators and parasites using remote, infrared-sensitive cameras.

They found that urban males call at higher rates using more complex and conspicuous calls than forest frogs.

Researchers also found that when given the choice, three-quarters of females chose the speakers playing the call of an urban male compared to a forest one.

When the team took frogs from the city into the forest they found urban males made their calls simpler, but forest frogs took longer to develop more complex calls when introduced to urban environments.

The study, published in Nature Ecology and Evolution, said that the city frogs had fewer predators and parasites but also fewer females to entice, which might explain why their calls were more complex and "sexier".

STRI staff scientist and study co-author Rachel Page said: "Just as we change our social relationships in cities, animals are changing their relationships and their behaviour in the radically altered biological communities we are creating across the globe."

Australian Associated Press