What sounds like harmonious song is really the noise of males trying to appear macho, say researchers.

And, just like humans, most of the boasting and trading of insults is done to impress the girls.

“Song sharing among sparrows is actually an aggressive behaviour akin to flinging insults back and forth,” said lead researcher Janet Lapierre, from the University of Western Ontario in Canada.

Sparrows have a large repertoire of songs but, when advertising for a mate, males stick to a ‘greatest hits’ selection that they perform repeatedly.

“The birds sing as aggressively and loudly as possible,” said Ms Lapierre.

Sparrows living in more competitive environments are likely to perform a more aggressive but smaller selection of songs, the researchers say.

This is like trying to prove themselves in a tough neighbourhood.

Those living in less competitive areas are more likely to sing their own songs rather than compete with other males by chirping the same tunes as them, the study adds.