Maya Skocilas — Year 12 Project website
Every winter, tens of thousands of humpback whales leave the icy feeding grounds of Antarctica and swim north along both coasts of Australia. It is one of the longest migrations of any mammal on Earth, and for a few months each year it passes right by our beaches.
Humpbacks (Megaptera novaeangliae) are baleen whales, which means they have no teeth. Instead they filter tiny krill through plates of baleen, gulping thousands of litres of water in a single mouthful. Adults grow to around 15 metres long and can weigh as much as 30 cars, yet they are famous for their acrobatics: breaching, slapping and singing in ways scientists still do not fully understand.
The name comes from the way they arch their back into a hump just before a deep dive. Look closely and every whale carries its own pattern of black and white markings on the underside of its tail, as unique as a fingerprint.
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Humpbacks feed almost entirely in summer, in the cold, krill-rich waters around Antarctica. When winter arrives the water is too cold for newborn calves, which are born without the thick blubber that keeps adults warm. So the whales head north to the warm, sheltered waters of the tropics to mate and give birth, and they barely eat for months on the way.
Two separate populations pass Australia. The east coast group swims up past Sydney and Byron Bay to the Great Barrier Reef; the west coast group travels up to the Kimberley. On the way home in spring, mothers and calves hug the coast, resting in bays like Hervey Bay and Eden, which is why spring is the best time to see them from land.
The pattern on the underside of a humpback's tail is unique. Researchers and citizen scientists upload tail photos to catalogues like Happywhale, which match the same whale year after year across the whole ocean.
Small tags attached to the whale's back send a GPS position each time it surfaces, showing the exact route, speed and how long each whale rests along the way.
Male humpbacks sing long, complex songs. Hydrophones moored on the sea floor can hear whales passing day and night, even when no one can see them.
Volunteer surveys from places like Cape Solander in Sydney have counted whales from the same cliffs every winter for decades, tracking how the population has recovered since whaling ended.
Tap a month to see where the whales are and what to look out for.
Whales do not spend much time at the surface, so each glimpse is a clue. Here is what each one means.
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breach.jpgThe classic humpback moment. The whale rolls forward and arches its back high out of the water, showing the small dorsal fin on the hump that gives the species its name. It usually means a deep dive is coming, so keep your eyes on the same spot.
Spot it: look for a low, dark curve and a puff of mist from the blowhole just before.
When a humpback dives steeply, its tail lifts clear of the water and the underside of the flukes faces you for a second or two. The black and white pattern is unique to each whale, which is how researchers tell them apart.
Spot it: a fluke-up dive means the whale may stay under for five to fifteen minutes.
Also called lobtailing. The whale hangs head-down and smacks its tail flat onto the surface, sometimes again and again. The sound carries a long way underwater and is thought to be a warning or a signal to other whales.
Spot it: a sudden white splash with no body visible, often repeated.
Humpbacks have the longest pectoral fins of any whale, up to five metres, almost a third of their body length. Rolling onto their side or back, they raise a fin and slap it down. It may be communication, play or a way to shake off barnacles.
Spot it: a long white "arm" waving from the water, usually while the whale is lying still.
The big one. A humpback drives itself upward with a few powerful tail beats and launches most of its 30-tonne body out of the water, twisting as it falls. Nobody is certain why: it could be communication, dislodging parasites, or simply fun.
Spot it: watch for white water a long way off. Breaches often come in sets, so a second one may follow.
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Humpbacks have made one of the great comebacks. After commercial whaling ended in the 1960s the east Australian population had fallen to a few hundred animals. Today it is more than forty thousand. But the ocean they migrate through is busier and dirtier than ever.
Boats that chase, crowd or cut across a whale's path force it to change course and waste energy it cannot spare on a months-long fast. Engine noise drowns out the songs whales use to find each other, and collisions with fast ferries and ships can be fatal. Entanglement in fishing gear and shark nets is now one of the biggest dangers on the east coast.
Humpbacks filter enormous volumes of water, so microplastics end up in their food and their stomachs. Long-lasting chemicals such as PCBs and heavy metals build up in blubber over a lifetime and are passed from mother to calf through milk. Warming seas are also shifting the krill the whales depend on.
Australia has national rules for getting close to whales. The idea is simple: we are visitors in their water. These are the main ones to remember.
Mothers and calves rest here on the way south. Calm, shallow water and very close encounters.
Jul – OctBoats leave from Main Beach for the "humpback highway", or watch for free from the Point Danger lookout.
Jun – NovThe warm, sheltered waters of the breeding grounds, where calves are born. Tours run from Airlie Beach.
Jul – SepWhales feed in Twofold Bay on the way home, something they rarely do on migration.
Sep – NovThe most easterly point in Australia. Whales pass almost under the lighthouse.
Jun – NovCape Solander and North Head: free, from the cliffs, with thousands of whales a season.
May – NovClear water and white sand beaches. Mothers and calves rest in the bay on the way south, often close to shore.
Jun – NovHumpbacks alongside whale sharks and manta rays on the west coast route.
Jun – OctThe first stops on the west coast as whales arrive from the Southern Ocean.
May – AugThank you to everyone who helped with this project. Maya: add the people, organisations and whale-watching crews you would like to thank here.
All photographs are by Maya Skocilas unless noted.