Did you know?
The Humpback whales of Eastern Australia.
Each year between May and November, Australia’s eastern coastline comes alive with the spectacular acrobatic displays of humpback whales.
After a summer of feeding on krill in Antarctic waters, these charismatic animals migrate north to sub-tropical waters where they mate and give birth.
During their annual migration of up to 10,000 kilometres, humpbacks attract thousands of visitors to coastal towns such as Eden, Nelson Bay, Byron Bay and Hervey Bay.
The exact timing of the migration period can vary from year to year depending on water temperature, sea ice, predation risk, prey abundance and the location of their feeding ground.
The majority of humpbacks in Australian waters migrate north from June to August, and back towards the Southern Ocean from September to November. Groups of young males typically lead the migration while pregnant cows and cow-calf pairs bring up the rear. Adult breeding animals form the bulk of the migration in the middle stages.
At a maximum length of 16 metres, the humpback is not the largest whale found in Australian waters but it is arguably the most iconic.
Everyone in Australian waters must follow regulations on how to behave around these animals, for example, touching or feeding them is not allowed. Vessels must travel carefully at low speed and stay at least 100 metres away, although a closer look is sometimes possible if curious whales choose to approach the vessel.
Physical Characteristics and Appearance
When it comes to physical size an adult humpback whale can grow to an average length of 16 metres long and weigh as much as 40 tonne. Note: One of the largest ever recorded humpback whales measured in at 27 metres long.
These marine mammals are generally either a dark grey or black color with white patches on their stomach and knobs (known as tubercles) covering their head.
From a visual standpoint the humpback whales body is thickest in the middle and tapers down towards the head and flukes.
The whales back is largely flat with a small dorsal fin located down the far side of its back, however when swimming the humpback may arch its back and flukes causing its back to look like a large hump.
In order to navigate the ocean these whales possess a large fluke and unusually long pectoral fins (about 1/3 the length of its body) which it uses for swimming, turning and propelling itself through the water.
Because the humpback is a baleen whale it possess baleen plates instead of teeth.
The baleen plates have bristles attached to them that act as a catchers mitt for capturing various small prey.
The bristles are bunched close together in order to prevent small prey from escaping but are spaced apart enough to allow water to easily pass through.
Another characteristic that is unique to baleen whales such as the humpback is the presence of two blowholes which are located on top of its head.
Diet and Hunting Methods
Humpback whales have a pretty diverse diet when it comes to the baleen whale suborder and are known for eating small fish, krill, salmon, herring, mackerel and capelin among other small prey.
Because the humpback does not possess teeth and has to swallow its food whole, these marine mammals are limited to consuming small aquatic animals.
These whales hunt and feed during the summer months in cold waters and migrate toward warmer tropical areas during the winter months to mate and bare offspring.
During the humpbacks feeding season, the whales hunt using a technique known as bubble net fishing, which involves a group of humpback whales swimming around their prey in a circle and blowing bubbles around their prey in order to herd the fish into a tight ball.
The whales will also create loud vocal sounds to scare the fish to the surface of the water and slap their fins against the water to stun the fish and immobilize them.
Once the fish are unable to move, the whales will swim up and lunge at the fish with an open mouth and engulf hundreds or thousands of small fish in a single gulp, while using their baleen bristles to separate the water and debris from their prey.
After capturing a mouth full of fish, the humpback will then push the water out of its mouth using its tongue and swallow the remaining prey.
Humpback whales feed most frequently during feeding season and use this time to build up their blubber stores in preparation for mating season.
During mating season humpback whales will fast (stop eating) and live off of the body fat/blubber reserves they acquired during feeding season so that they can focus on migration and mating.
Although they may feed from time to time during mating season, it is rare.
Habitat and Migration
Humpback whales are known to migrate to different locations depending on the time of year.
These marine mammals are known for their massive size and haunting whale songs that are often produced during mating season when male humpback whales sing to compete against other males for the right to mate with a female humpback.
In terms of location and habitat, humpback whales can be found traveling throughout all of the worlds major oceans.
During the summer months, which is their feeding season, these whales can be found inhabiting the colder regions of the world such as Alaska and Antarctica where large quantities of fish, squid and krill can be found.
Once the winter time rolls around and large ice caps begin to form, these whales can be seen migrating to locations such as Hawaii and the gulf of Maine where they spend the majority of their time mating and bearing offspring.
As with other species of baleen whale the humpback whale has two primary seasons known as feeding season (the summer months) and mating season (the winter months).
During their migration these whales are known to travel as far as 16,000 miles making them one of the furthest migrating species in the world.
Despite being able to consume large quantities of food, these whales are known to almost completely forgo eating during the mating months and will live primarily off of the fat stores they obtained during feeding season.
Once these whales have finished mating and bearing offspring, they travel back towards the northern and southern polar hemispheres where they can stock up on large quantities of food and prepare for the next mating season.
In many cases the mature and experienced whales will travel ahead of the younger whales during migration trips and lead them to the right destinations.
Interestingly, although these whales can be seen migrating, hunting and mating in large groups they are generally very solitary and non social creatures that prefer traveling alone or in small groups of two to three.
In these cases a pod may consist of a mother whale and her child or two friends that have formed a temporary loose bond.
When it comes to hunting, traveling or mating however, several dozen whales may be seen aggregated together and working cooperatively, in order to obtain their goals.
During reproduction cycles, female whales will bear a single offspring once every 2 – 3 years while they are fertile, with the average gestation period lasting 11 – 12 months.
The 11 – 12 month gestation period allows the female whale to return to its warmer, safer mating environment where it can bear its young, nurture it and prepare for the long migration trip back to its feeding grounds.
Humpback whales prefer to feed in areas where large supplies of food are available and mate in warm climates that may provide some safety during mating season, when they give birth to their new-borns and nurse their young.
When compared to other animals, humpback whales are known for traveling great distances during migration periods and may travel as much as 16,000 miles per year, making them one of the furthest traveling animals in the world.
Why do whales breach?
Breaching is when most or all of the whale’s body leaves the water. Humpback whales can use their powerful fluke (or tail fin) to launch themselves out of the water. And while many other whale species breach, humpback whales seem to breach more frequently.
Scientists suspect humpback whales are breaching and slapping their fins and flukes on the surface as a way of communicating. It is believed that all slapping creates sounds used to send messages to other whales, and the big splashes are for sending messages long-distances. Sound travels further and more rapidly underwater than it does on land and could possibly communicate messages to other whales.
These forms of communication are believed to be used to show dominance, youth and health during mating season in order to prove to other whales that they are healthy, fit and a good partner to mate with.
Some males whales will even charge other males to show their dominance and claim their territory, however it is rare that any serious harm will come to either whale.
As a species, humpback whales typically travel alone or in small pods of two or three.
They are largely solitary animals, however they do communicate under certain circumstances such as when hunting for food, mating and during migrations.
Whale Songs & what they mean
The Humpback is well-known for its majestic whale songs which are often heard during mating season when groups of male whales sing in order to attract a female to mate with.
In addition to playing a role in their mating rituals whale songs are also believed to play other roles in the humpback whales social structure, however as of now little is known about why they produce these sounds.
Due to their large size the sounds these whales make can be heard many miles away and are described as a combination of moans, howls and cries among other sounds which can go on for hours at a time.
In fact whales that are miles apart can be heard creating the same sounds together in unison and will change their songs in harmony with other whales.
How do whales breathe?
Whales and dolphins are mammals and breathe air into their lungs, just like we do. They cannot breathe underwater like fish can, as they do not have gills. They breathe through nostrils, called a blowhole, located right on top of their heads.
On average, adult humpbacks surface every 7-15 minutes.
Calves must swim up to the surface every 3-5 minutes to catch some air to breathe.
Reproduction and Lifespan
When it comes to giving birth female humpback whales are known to reproduce once every two or three years on average while fertile.
The average gestation period (the period between fertilization and birth) for a humpback whale often lasts between 11 and 12 months.
The calves (baby whales) are typically nursed by their mother for the first year and are fed milk daily through the mothers nipples.
The milk carries a very high fat percentage of around 35% which helps the milk travel through the water and to the baby whales mouth.
The mothers milk is packed with essential nutrients and fats to help the child grow and remain healthy during its first year.
Calves can drink as much as 600 litres of milk per day and over the course of several months they can develop a thick layer of blubber which helps protect them from the cold waters as they travel back towards the polar ice caps during their feeding season.
When the young humpback whale becomes sexually mature (usually between the ages of 5 – 9) they may begin mating and reproducing offspring of their own.
In terms of lifespan a healthy humpback whale is believed to have a lifespan of up to 50 years.
How do whales sleep?
Marine mammals such as whales spend their entire lives at sea. So how can they sleep and not drown? Observations of whales and dolphins in the wild, show two basic methods of sleeping: they either rest quietly in the water, vertically or horizontally, or sleep while swimming slowly next to another animal
When marine mammals sleep and swim at once, they are in a state similar to napping. Young whales and dolphins actually rest, eat and sleep while their mother swims, towing them along in her slipstream--a placement called echelon swimming. At these times, the mother will also sleep on the move. In fact, she cannot stop swimming for the first several weeks of a newborn's life. If she does for any length of time, the calf will begin to sink; it is not born with enough body fat or blubber to float easily.
Lots of swimming will tire an infant, producing a weak animal susceptible to infection or attack. Adult male dolphins, which generally travel in pairs, often swim slowly side by side as they sleep. Females and young travel in larger pods. They may rest in the same general area, or companionable animals may pair for sleeping while swimming.
It is not clear whether cetaceans undergo dream sleep. Rapid Eye Movement (REM)--a characteristic of deep sleep--is hard to discern. But a pilot whale was noted as having six minutes of REM in a single night.
To avoid drowning during sleep, it is crucial that marine mammals retain control of their blowhole. The blowhole is a flap of skin that is thought to open and close under the voluntary control of the animal. Although still a matter of discussion, most researchers feel that in order to breathe, a dolphin or whale must be conscious and alert to recognize that its blowhole is at the surface.
Finally, these animals have a higher tolerance for carbon dioxide (CO2). Their brains do not trigger a breathing response until the levels of CO2 are much higher than what humans can tolerate. These mechanisms, part of the marine mammal diving response, are adaptations to living in an aquatic environment and help during the process of sleeping.
Threats from humans & the environment
Even though they are no longer considered highly endangered, these whales still face a number of threats from humans such as:
Noise pollution – As more and more artificial sounds enter the oceans atmosphere growing concerns are developing regarding the likelihood of man-made sounds affecting the hearing of various marine mammal species. These sounds may include sonar, loud jet engines and explosives among other noises.
Water pollution – Chemical pollution from oil and other toxic chemicals can have a dramatic affect on whale populations and affect their food supply. Poisoned fish could lead to sickness and death among the whales that consume these foods.
Collisions with boats – The increasing use of commercial/personal boats can lead to congested areas of water that may increase the chances of a whale being struck by a passing boat.
Overfishing – Areas that are being over fished could lead to shortages in food supplies which could force the marine mammals to relocate or deal with having difficulties finding food.
Although not fully understood some researchers and biologists are showing growing concerns regarding the impact some of these types of activities can have on various marine life.
How you can help protect whales
Please don’t litter – rubbish that ends up in our oceans can be deadly to marine animals.
Always stay at least 100 meters away from whales and never touch or feed them, even if they approach you.
Report any injured or stranded whales to your local environment agency.