Whales may sing for their supper, a study in the open access journal Scientific Reports suggests.
Humpback whales (Megaptera novaeangliae) work together whilst foraging on the bottom for food – but how do they co-ordinate their behaviour? Susan Parks of Syracuse University believes she may have the answer.
Her research group have been monitoring humpback whales for a decade.
This study used digital acoustic tags to record sounds made by the whales when feeding on the bottom (at around 30-35 m depth) of the Northwest Atlantic. The data showed that whales often feed on the seafloor in close co-ordination, matching diving and behaviour on the seabed. The researchers heard the whales making a previously undescribed sound which sounded like “tick-tock”.
The scientists noticed that the bottom-feeding sounds, were only produced under low-light conditions whilst other humpback whales were nearby.
Why the whales make the noises is unclear. It may be to co-ordinate timing of feeding activities under low light conditions, to alert other humpback whales to the location of particularly good patches for feeding – acting like a dinner bell – or to flush out the prey.
“Hints of behaviour suggest that other whales who overhear the sounds are attracted to them and may eavesdrop on other whales hunting for food,” Professor Parks says.
Dinner for the humpbacks feeding on the bottom was mainly sand lance. These are eel-like fish which bury themselves in the sand of the ocean floor.
Humpback whales forage across habitats on a wide diversity of prey, ranging from krill to larger schooling fish species, using a variety of feeding strategies. This novel acoustic cue used whilst foraging on a bottom-dwelling prey provides yet more evidence of the learning abilities of humpback whales.
Scientific Reports is a primary research publication from the publishers of Nature.
Parks, Cusano, Stimpert, Weinrich, Friedlaender & Wiley. Evidence for acoustic communication among bottom foraging humpback whales Scientific Reports 4, Article number: 7508 (2014)
Biologist reveals how whales may sing for their supper