Meet the Whales
"In the end we will conserve what we love;
we will love what we understand"
Baba Dioum, 1968
The goal of the Keiki Kohola project is to ensure that humpback whale mother and calf pairs are fully protected during their time in Hawaii. To this end we conduct management-based research that can be directly applied to ensure targeted, effective protection.
Recently renamed as the Hawaii Distinct Population segment, Hawaii’s humpbacks comprise around 60% of the North Pacific stock. Within Hawaii, 80% of all mother and calf pairs choose the waters of the Au’Au Channel, between the islands of Maui and Lanai as the wintertime home. Over the last twenty years, we have conducted research focused on the early development of humpback whale calves, the behavior of mother-calf pairs and fluctuating dynamics of Hawaii’s maternal groups.
Humpback whale calves, like many marine mammals, go through a fast and demanding period of development, right after birth. While newborn calves, known as neonates, can barely swim or hold their breath, within 6 weeks they’ll be ready to make the 2500km swim to their feeding grounds.
The youngest calves seen in Maui waters are typically small in size relative to mom. They have pale, floppy pectoral fins, a dimple at the back of the neck and a furled dorsal fin. In some, but not all neonates, fetal folds may still be visible and the calf may be very light in overall color. The calf is often up around the eye of the mother, in front of the pectoral fin.
As calves mature, they grow in length and girth, reaching up to a third of the length of their mother. Their color darkens and typically, they swim along beside the mother, over the pectoral fin. The dorsal fin straightens as the calf matures. We estimate that they will begin their migration to Alaska somewhere between 4 and 6 weeks of age.
Humpback whale calf behavior varies with age
To determine the relative age of a humpback whale calf, look closely at the dorsal fin. From birth onwards, the dorsal fin steadily unfurls. However, the oldest calves have an entirely erect dorsal fin and the proportion stays constant over the season. This suggests that calves with an erect dorsal are ready to migrate.
Cartwright, R., Sullivan, M., 2009. Behavioral ontogeny in humpback whale (Megaptera novaeangliae) calves during their residence in Hawaiian waters. Mar. Mammal Sci. 25, 659–680.
Why do baby whales breach?
There’s no more exciting sight than the view of a humpback whale as they execute a full breach – what an acrobatic feat!
But why would young calves spend so much precious energy breaching? In fact, it’s a key component of their development, leading to a build-up of myoglobin in their major muscles, which in turn supports the development of breath-hold capacity in young calves.
Cartwright, R., Newton, C., West, K.M., Rice, J., Niemeyer, M., Burek, K., Wilson, A., Wall, A.N., Remonida-Bennett, J., Tejeda, A. and Messi, S., 2016. Tracking the development of muscular myoglobin stores in mysticete calves. PloS one, 11(1), p.e0145893.
Got milk: How much milk do humpback calves drink?
While urban myths around the internet suggest that mothers produce upwards of 100 gallons of milk a day, this is not accurate. Given that mothers are not feeding and relying solely on stored energy, thus would actually be impossible to sustain. Updated estimates, based on the calves’ growth rates, daily activity budgets and assimilation efficiency, indicate that calves receive between 11 and 15 gallons of maternal milk per day.
Hawaii’s Gentle Giants; humpback whales of the North Pacific. Published by Golden Plover Press; coming winter 2023.
Maui’s amazing moms
For pregnant humpback whales, their round-trip journey of over 4000 km across the waters of the North Pacific -- while fasting--, is a feat in itself. On top of that these amazing moms give birth to a 2,000 lb. calf, provide milk for their calf, keep their calves safe from predation and guide them back to their feeding grounds, all while still maintaining their fast.
Throughout 3 decades of research around the world, birthing in humpback whales has remained a mystery. However, in recent years, that has changed. Portions of the birth have been documented in multiple different breeding regions. In Maui waters, moms have been seen in the process of giving birth, and in 2021, the KKP research team documented an entire birth, in the waters between Maui and Lanai.
Link to the poster from the upcoming SMM conference
Nursing on the fly
Nursing is another maternal mystery, with very few records of humpback whale moms nursing. Reasons could be that nursing whales are infrequent, or easily disturbed by divers in water. During KKP research activities, nursing has been recorded both by divers in the water and from the air, however the mom is typically in motion. Nursing on the fly like this may seem challenging, however it would ensure that the calf follows the mother continually, staying close – and safe – during these early days.
Publication in preparation.
Favored regions for Maui’s moms
In the waters around Maui, moms can raise their calves in safety, beyond the range of their key predator, the transient Orca. Mom-calf pairs travel widely through the island chain, however they typically favor the coastal waters around West Maui. In the seventies, mom-calf pairs were most frequently seen within a half mile of this shoreline, where calm, sheltered waters provided perfect nursery conditions. Today, vessel traffic in these areas has increased. Although mom-calf pairs still favor Maui waters, their favored region now lies one to two miles from shore, where water depths range between 120 to 180 feet.
Cartwright, R., Gillespie, B., LaBonte, K., Mangold, T., Venema, A., Eden, K., & Sullivan, M. (2012). Between a rock and a hard place: Habitat selection in female-calf humpback whale (megaptera novaeangliae) pairs on the Hawaiian breeding grounds. PLoS ONE, 7(5). doi:10.1371/journal.pone.0038004
Fluctuating birth rates
Between 2014 and 2015, a marine heatwave spread across the Central North Pacific. Nicknamed the blob, these warm waters reached the feeding grounds used by North Pacific humpback whales by 2016. Water temperatures increased by 4 degrees, sending food stocks into a steep decline. Numbers of whales seen in Maui waters declined, and by 2018, sightings of new calves in Maui waters had fallen by over 75%. In recent years, numbers have rebounded. Still, these events highlight both the fragility of the recovery of humpback whales, and their vulnerability to the impending impacts of climate change.
Cartwright, R., Venema, A., Hernandez, V., Wyels, C., Cesere, J., & Cesere, D. (2019). Fluctuating reproductive rates in Hawaii's humpback whales, Megaptera novaeangliae, reflect recent climate anomalies in the North Pacific. Royal Society open science, 6(3), 181463.
Escorts – friend or foe?
While 80% of mother-calf pairs in Maui waters are accompanied by a male escort, the escort’s interest in the mother is something of a conundrum: As some mothers may be fertile shortly after birthing, the mother presents a possible mating opportunity. But for a new mom with a calf in tow, mating again can carry heavy costs. A single male can act as a body guard, steering rowdy multiple male groups away, however in this recently captured clip, the escort seems to be attempting to come between a mother and her young calf. Clearly, this story continues…
Cartwright, R., Sullivan, M., 2009. Associations with multiple male groups increase the energy expenditure of humpback whale (Megaptera novaeangliae) female and calf pairs on the breeding grounds. Behaviour 146 11: 1573-1600
For the full story of Maui’s humpback whales, pick up a copy of the new book, “ Hawaii’s Gentle Giants”, compiled and published by the Keiki Kohola Project. Profits support the work of the Keiki Kohola Project.