Researchers in Australia have discovered why humpback whales jump.
Researchers working in Queensland, Australia have discovered humpback whales breach to communicate with other pods of whales over 4 km (2.5 miles) apart. Wanting to know why these whales breach when migrating, researchers observed 94 different groups of whales during their migration to Antarctica. Their findings were published in Marine Mammal Science in November 2016.
The research into humpback whales surface behaviours was conducted as part of the Behavioural Response of Australian Humpback Whales to Seismic Surveys (BRAHSS) project at Peregian Beach, Queensland. The researchers wanted to know why humpback whales breach and perform other surface behaviours frequently when they are migrating. Whales usually fast during their migration, living off body fat, and such behaviours use a lot of energy they cannot afford to spare without good reason.
Ninety-four groups of whales were observed during their migration south, past the Australian coast en-route to Antarctica, during September and October of 2010 and 2011. Observations were undertaken by staff intensively trained and tested in the weeks prior to the fieldwork. They recorded the occurrence of surface behaviours, such as fin slapping the water and breaching, to discover what they might mean. The observations were combined with acoustic monitoring and data on the social and environmental context of each whale group before drawing their conclusions.
They discovered surface behaviours were more common on windy days and when other groups of whales were far away. The behaviours serve multiple communication purposes for migrating whales; with breaching used to communicate between far-apart groups and fin slapping used close-range. Fin slapping was also used when groups of whales came together or separated.
Researchers concluded the noise from fin slaps and breaching travels long distances and may be used when vocal noises, such as song, would be lost due to boat and weather noise. Whilst only migrating whales were studied, their behaviours may have the same purpose wherever, and whenever, they occur. Humpback whales fin slap and breach throughout the year.
Humpback whale song is complex, only produced by males during their sexual display, and can be audible over distances of 10 km (6.2 miles). The male song lasts ten to twenty minutes and is repeated for hours at a time. The whales’ social sounds, such as from fin slaps and breaches, lack the pattern of song and are produced by both sexes in various contexts. Humpback whales migrate around 25,000 km (16,000 miles) each year; feeding in polar waters and breeding in warmer waters. Entanglement in fishing gear, collision with ships and noise pollution are threats to their survival.