You might not be that impressed to receive a clump of grass or branches on a first date, but a boto dolphin might think differently. A new study suggests that these Amazonian dolphins wave bits of flotsam to attract mates.

The boto is a freshwater river dolphin that swims through the currents of the Amazon and the Orinoco. They are elusive creatures that are difficult to study, so very little is known about their social lives.

The botos pick up branches, sticks, vegetations and lumps of clay in their mouths, often thrashing them against the water surface or throwing them with jerks of the head. None of the objects are edible and the carriers often swim in a ritualised way, spinning