A South American river dolphin uses branches, weeds and lumps of clay to woo the opposite sex and frighten off rivals, scientists have discovered.However, just like other river dolphins such as the Baiji, the prospects for the Boto are not great, despite its apparent decent population of "tens of thousands".
Researchers observed adult male botos carrying these objects while surrounded by females, and thrashing them on the water surface aggressively.
Projeto Boto scientists are regularly finding dead dolphins, either harpooned or entangled in ropes.
"We lost half of the animals from our study area in just five years," said Tony Martin. [Sea Mammal Research Unit at St Andrews University]
"They may be fairly numerous now, but they're going downhill fast and we can't see any end to it."