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Bella is a humpback whale from Australia that our research team has sighted in seven different years since 1992. During that time, we’ve learned so much about her!
We identify Bella (and other individual whales) through a technique known as photo-identification. Each humpback whale has a unique pattern of marks and coloration on its tail flukes. Pacific Whale Foundation researchers photographically identify individual animals using these marks and develop long-term case histories of known whales. You can see one of Bella’s identification photos on your adoption certificate. And as you’ll learn from this story, this technique has allowed us to identify Bella repeatedly.
Humpback whales are migratory animals, generally moving between cool water feeding areas (where they spend summer, the warmer months of the year) and warmer water breeding areas (where they spend winter, the cooler months of the year).
Bella is part of a population of East Australia humpback whales that migrates each year along the east coast of Australia, following this schedule:
During December-April, these East Australia whales feed in Antarctic waters, many near the Balleny Islands.
In late May, the whales begin to migrate along the east coast of Australia northward towards the Great Barrier Reef, where they mate, give birth and care for their young.
In mid-July, the whales begin to travel south to their Antarctic feeding grounds. During this return trip, many stop in Hervey Bay and other bays along the Queensland coast.
By November, most of the whales have left Queensland waters.
Pacific Whale Foundation has been studying whales in Hervey Bay for 28 years. In fact, all of our sightings of Bella have occurred in Hervey Bay.
Hervey Bay is a fascinating place to study humpback whales. Of the 14,000 humpback whales that migrate along Australia’s eastern coast each year, more than 30% of this population is believed to stop in Hervey Bay during the migration. The large number of whales in this relatively small area results in extraordinary whalewatching.
Hervey Bay is 4,000 square kilometers, bound to the west by the mainland of Australia and by Fraser Island to the east. Most of the bay is shallow (less than 18 meters deep) and has a sand or mud floor. Hervey Bay is part of the Great Sandy Marine Park.
The first time we encountered Bella was in Hervey Bay on August 16, in 1992. At the time, Bella was a subadult, a whale that had not yet reached adulthood and the point where she could mate or bear offspring. Bella was with two other whales.
We sighted Bella there again on August 17, in about the same area.
We didn’t see Bella again until September 28, 1998 – six years later! She had matured and was now a mother with a calf.
A humpback whale’s gestation period is nearly a year. The calf survives on its mother’s fat-rich milk for 6 to 8 months, drinking about 300 litres per day.
Two male whales were milling around her with her and the calf. When people see a male whale with a female and calf, they often mistakenly assume the male is the father – but that’s not the case. Males and females do not form long term bonds. In fact, their association with each other may last for a few hours or less than a day. The female brings up the calf alone. From time to time, males will spend time with the mother and calf. Because female humpback whales can become pregnant again even while raising a calf, the males may simply be looking for an opportunity to mate with her.
Our researchers also saw Bella in Hervey Bay on October 1 of that year.
A mother whale will remain with her calf for about a year in order to feed it the fat-rich milk she produces – superfood that allows the calf to grow rapidly! The calf nearly doubles in length during the first year. Calves begin to feed on fish at around 6 months and are usually weaned after about 10 to 12 months.
This fact is important to know, because when we saw Bella again two years later, in the year 2000, she was with a calf – meaning she had become a mother again! We sighted Bella in Hervey Bay on three different days that year, on September 9, 11 and 12. When we saw Bella and the calf on September 12, they were very active and were breaching!
Two years went by again. And then, on September 13, 2002, right on schedule, there was Bella in Hervey Bay – and once again, she was with a calf! This was the third known calf that she’s produced. The calf was breaching and Bella was slapping her peduncle fins (the long fins on either side of the body that whales use to turn and steer) on the surface of the sea. Peduncle fin slaps create a loud “thwack” that can be heard underwater and are thought to be a means of communication.
After the passage of four years, Bella was again found in Hervey Bay, on September 8, 2006. Again, she was with a calf, and the twosome were very active. Both Bella and the calf were breaching. She was “pec slapping” and also head slapping – lifting her head above the sea and slapping it down with a huge splash. These high energy behaviors are reason to believe that Bella is very good at producing robust, healthy calves – and is also adept at staying healthy herself.
Another four years passed, before we saw Bella again. We were rewarded with two sightings of her that year (2008) on September 11 and 16. She was with yet another calf. At the time we encountered them, both animals were resting at the surface. Humpback whales don’t “sleep” as we know it, but they are known to “log” at the surface, as a form of resting.
A year later, we saw Bella again, on September 3, 2009. She was with a calf. What was especially notable was that Bella was in a pod that included another mother and calf. Our research team never sees mother and calf pods associating with other mother and calf pods in Hawaii, but it is fairly common in Australia. At the time of our encounter, both calves were proving to be energetic youngsters. They were breaching! At one point, Bella was observed pushing her calf towards our boat. Perhaps she was comfortable with our research boat, after having seen it on so many occasions over the years.
Our researchers are intrigued with multiple mother/calf pods, such as the ones encountered in Hervey Bay. In general, humpbacks are considered a relatively asocial species and in Hawaii, we have noted that mothers with calves appear to actively avoid one another. However, our researchers have repeatedly observed multiple mother-calf pods at two points on southward migration along Australia’s coast – in Hervey Bay, and also further south along the coast, near our research site in Eden.
Our team has observed multiple mothers with calves in Hervey Bay since 1987. Their sightings of multiple mother-calf pods have increased in frequency since 2000. On average, 2 multiple mother-calf pods were observed each season prior to the year 2000, whereas 14 pods have been observed each season since.
The multiple mother-calf groups were most frequently engaged in surface active behaviors (including pec slapping, head slapping and breaching). It is possible that the mother-calf groups serve a social function.
Another theory is that association between mother-calf pairs may simply be the result of increasing numbers of whales attempting to utilize a limited areas of preferred habitat.
The population of East Australia humpback whales is increasing. Prior to commercial whaling, this population was estimated to be at around 10,000 but it was decimated to fewer than 500 individuals during the early 1960s.
The increasing number of whales is good news. During the 1950s and early 1960s, humpback whales along Australia’s eastern coast were hunted to near extinction. It was believed that fewer than 500 whales were left.
Humpback whales became listed as a vulnerable species under the Queensland Nature Conservation Act 1992, and Nature Conservation (Wildlilfe) Regulation 2006 and as vulnerable under the Federal Environment Protection and Biodiversity Conservation Act 1999. Thanks to these protective measures, the east Australia humpback whale population is increasing at a rate of about 11% each year. Scientists estimate there are 14,000 whales in this population today.
Bella, as a very productive female who has given birth to at least six calves, is a hero in the story of the whales’ recovery. Through the data that we’ve gathered about her and other female humpback whales in Hervey Bay, we’ve learned that mature females in this area give birth on average every 1.75 years. About 24% have given birth annually for at least a two or three year consecutive stretch. Our longest known reproducing female has been calving for at least 22 years.
We look forward to learning more about the reproductive rates of humpback whales in the future, and we especially hope to see Bella again and again in Hervey Bay! We will let you know when we encounter this beautiful and valuable female whale again. Most of all, we thank you for adopting Bella and supporting our research and advocacy efforts on behalf of all humpback whales in the Pacific.