Wildlife in False Bay - Humpback whales

Humpback whale underwater. 

South Africa is a famous destination for watching marine mammals such as southern right whales, humpback whales and various species of dolphins. Humpback whales are friendly, often interacting with other marine animals, and the males are known for performing magical songs. This species of whale generally lives between 40 to 45 years of age and thrives in all oceans of the world.  

Humpback whales from the southern hemisphere are slightly smaller in size than those from the northern hemisphere, with females reaching 13,7 metres in length and males at a smaller size reaching 3,1 metres in length. These pleasant and giant mammals, weigh anything between a heavy 27 215,5 kg to 45 359,2 kg. The four-chambered heart of an average humpback whale weighs in at about 195 kg.

Their bodies are stocky in shape, dark in colour with white patches and a distinctive, sloping hump, hence the name of humpback whale. They have a large head on which three irregular rows of knobs called tubercles are situated, and throat grooves that run from their chin to navel. Their bodies are equipped with white coloured pectoral fins that are almost a third of its body length and a short, dorsal fin.

Habitat

Humpback whales follow a migration route during winter for mating and calving after feeding in polar waters during summer.

In the southern hemisphere, during winter these whales migrate further north from the pole, in order to mate and birth their calves, with numbers at the highest in June and July. In Africa, humpback whales are found along the Southern-African coasts off Angola, Mozambique and of course South Africa.

Humpback whale breaching. 

Diet

Much like the southern right whale, humpback whales are seasonal feeders, eating mostly during summer and living off their fat reserves during the colder months. Humpback whales, on average, eat between 2000 – 2500 kilograms of food, and have a large and varied diet that include various subspecies of krill and small fish.

They hunt using various methods but the most common would be ‘bubble netting’ which entails a pod forming a circling under water, then blowing a wall of bubbles as they swim to the surface in a spiral formation. The wall of bubbles traps their prey which the whales then catch as they move to the surface.

Behaviour

While both male and female humpback whales produce vocalisations, only males perform ‘songs’ of varied pitches and sounds, lasting up to 30 minutes and ranging between 20 to 9000 Hz. ‘Songs’ differ according to the locality of the male humpback whales and patterns each year.

Whales live in the ocean but are air-breathing mammals that must surface in order to breath in fresh air to fill up their huge lungs. While sleeping they must continue to breathe and so it is believed that one half of their brain sleeps while the other half that is not asleep surfaces, breathes and then returns beneath the water without awakening the half asleep.

Humpback whale mother with calve.

Reproduction

During the breeding season, unlike southern right whales, male humpback whales form competitive groups around a female and fight to win her over. Humpback whales pass through False Bay in May and June on route to mate and birth in warmer waters off the coast of Mozambique and Angola, and are later seen in October and November on their return trip.

Like southern right whales, female humpback whales birth a calf every three years. Gestation lasts about a year after after which a single calf is born, and although seldom, twins are known to occur. Calves are generally about 4.2 metres in length when born and go on to suckle for between ten to eleven months.

Did you know?

The only known natural predator to hunt humpback whales are a pack of killer whales.  

These whales are listed as an endangered species and are protected against hunting by law.