Behavior

Whales perform a spectacular array of surface behaviors that are among the most dramatic displays in the natural world. These behaviors serve various functions including communication, parasite removal, play, and social bonding, and they vary significantly across species and contexts. Breaching is perhaps the most iconic whale behavior. A breaching whale propels most or all of its body out of the water and crashes back down with an enormous splash. Humpback whales are the most frequent and acrobatic breachers among the great whales, sometimes launching their entire 40-ton body clear of the surface and twisting in midair before landing on their backs or sides. The force of a humpback breach generates a thunderous sound that can be heard for miles underwater, leading some researchers to suggest that breaching serves as a long-distance acoustic signal. Other hypotheses include parasite removal, since the impact can dislodge barnacles and whale lice, as well as communication of excitement, alarm, or dominance. Right whales are also enthusiastic breachers, and their breaches are particularly spectacular given their stocky, heavy-bodied build. Sperm whales, gray whales, and even blue whales have been observed breaching, though less frequently. When a 150-ton blue whale breaches, it is one of the most awe-inspiring sights in nature, though it occurs so rarely that few people have witnessed it. Spy-hopping is a behavior in which a whale rises vertically out of the water, head first, until its eyes are above the surface, then holds that position for several seconds before sinking back down. This behavior appears to be a deliberate attempt to look around above the waterline. Killer whales and gray whales are particularly known for spy-hopping. Killer whales have been observed spy-hopping near ice floes, apparently scanning for seals resting on the ice, and near boats, seemingly inspecting the humans aboard. Lobtailing, or tail slapping, involves a whale lifting its tail flukes out of the water and slapping them forcefully against the surface. This produces a loud crack that carries both above and below the water. Humpback whales lobtail frequently and may repeat the behavior dozens of times in a row. Studies have shown that lobtailing rates increase in windy conditions and when other whales are farther away, supporting the hypothesis that the behavior functions as an acoustic signal. Pectoral fin slapping, in which a whale lies on its side and repeatedly slaps the water with its long pectoral fin, is common in humpback whales and may serve similar communicative functions. Gray whales exhibit a unique surface behavior called friendly behavior, particularly in the breeding lagoons of Baja California. Mother gray whales and their calves actively approach whale-watching boats, allowing and even seeking physical contact with humans. This remarkable behavior, which has developed only in recent decades after the end of gray whale hunting in these lagoons, demonstrates the behavioral flexibility and curiosity of these animals.

Whale social structures are remarkably diverse, ranging from largely solitary lifestyles to some of the most complex and enduring social systems found in any mammal. The type of social organization a species exhibits is closely tied to its feeding ecology, predation risk, and reproductive strategy. Killer whales have one of the most stable and complex social structures of any animal. Resident killer whale populations are organized into matrilineal pods, groups centered around a matriarch and her descendants. Both sons and daughters remain with their mother's group for life, an extremely unusual arrangement in the animal kingdom. These pods form larger clans that share a common vocal dialect, and clans are grouped into communities. The matriarch, often the oldest female in the pod, serves as a repository of ecological knowledge, guiding her family to productive feeding areas and leading them through difficult conditions. Research has shown that the death of a matriarch significantly reduces the survival rate of her offspring, particularly her adult sons, highlighting the critical role these elder females play. Sperm whales have a different but equally fascinating social system. Females and their young live in stable family units of 10 to 20 individuals that travel, feed, and care for calves cooperatively. These groups practice communal babysitting, with one or more adults remaining at the surface to watch over calves while other group members dive to great depths to hunt squid. Adult males leave these family groups as adolescents and either live alone or form loose bachelor groups, only rejoining female groups temporarily during the breeding season. Each sperm whale family unit has its own distinctive pattern of echolocation clicks, called a coda dialect, that serves as a group identifier. Humpback whales have a more fluid social structure described as fission-fusion, in which associations between individuals change frequently. Humpbacks may be seen alone, in pairs, or in small groups that form and dissolve over hours or days. The most stable humpback association is the mother-calf bond, which lasts approximately one year. During the breeding season, males form competitive groups around females, jostling and battling for mating access in dramatic displays that can involve head-butting, tail slashing, and underwater charging. Beluga whales are highly gregarious, often gathering in groups of hundreds or even thousands at river mouths and coastal areas during summer. These large aggregations appear to serve social and reproductive functions, and belugas within them engage in frequent physical contact, play, and vocal interaction. Narwhals also form groups of varying sizes, with loose aggregations of hundreds sometimes observed during migration. The social organization of bowhead whales is less well understood due to the remote Arctic habitat they occupy, but they appear to form small, fluid groups that may aggregate at feeding areas. Pilot whales, like killer whales, live in stable matrilineal groups with strong social bonds that persist for life, contributing to their vulnerability to mass strandings when group cohesion leads an entire pod to follow a stranded individual onto shore.

The bond between a whale mother and her calf is one of the strongest and most enduring parent-offspring relationships in the animal kingdom. Whale mothers invest enormous energy and time in raising each calf, a strategy that reflects the long lifespans, slow reproduction rates, and complex social lives of cetaceans. From the moment of birth, a whale calf is dependent on its mother for nutrition, protection, and learning. Newborn calves must surface to breathe within seconds of being born, and mothers have been observed gently nudging their calves to the surface for their first breath. In the early days of life, mothers and calves maintain almost constant physical contact, with calves often swimming in their mother's slipstream to conserve energy. This close positioning, called echelon swimming, allows the calf to be carried along by the hydrodynamic wake created by the mother's body. Humpback whale mothers are fiercely protective of their calves. They will position themselves between their calf and any perceived threat, including killer whales, boats, and even human divers. Humpback mothers have been documented actively defending not only their own calves but also the calves of other whale species and even seals from killer whale attacks, a behavior that has puzzled scientists and may represent a generalized anti-predator response or a form of altruism. The nursing period varies by species but typically lasts 6 to 12 months for most great whales. Blue whale calves consume approximately 380 liters (100 gallons) of their mother's milk per day, gaining about 90 kilograms (200 pounds) daily. This milk is extraordinarily rich, containing 35 to 50 percent fat, compared to about 4 percent in cow's milk. The energy cost to the mother is enormous; a nursing blue whale mother may lose up to 50 tons of body weight during the months she is feeding her calf, converting her own blubber reserves into the calorie-dense milk her calf needs. Killer whale mothers maintain the longest mother-offspring bonds of any whale species. Both sons and daughters remain with their mothers throughout their lives, and mothers continue to share food with their adult offspring. Research on Southern Resident killer whales has demonstrated that mothers share salmon with their adult sons, particularly during periods of food scarcity. The death of a mother dramatically increases the mortality risk for her adult sons, suggesting a level of lifelong dependence that is rare among mammals. Sperm whale calves benefit from the cooperative care system of their family unit. While their mothers dive deep to hunt, calves remain near the surface under the watchful protection of other adult females in the group. These babysitters nurse, protect, and socialize with calves that are not their own, a form of alloparenting that strengthens group bonds and increases calf survival rates. This communal approach to childcare allows sperm whale mothers to make the long, deep foraging dives they need without leaving their calves unprotected.

Whales communicate using a rich array of acoustic signals, physical gestures, and body language. The complexity and flexibility of whale communication systems are among the strongest evidence for their high intelligence and social sophistication. Acoustic communication is the primary means by which whales maintain social bonds, coordinate activities, and convey information. Killer whale pods use distinctive vocal dialects, repertoires of call types that are unique to each pod and passed down from mothers to offspring. These dialects serve as acoustic badges of group identity, allowing killer whales to identify pod members even over long distances. The complexity of these learned vocal traditions has been compared to the cultural transmission of language in human societies. Humpback whale males produce the famous whale songs that can last for hours and evolve over time within and between populations. These songs represent one of the most elaborate acoustic displays in the animal kingdom and may serve as honest signals of male fitness to potential mates. The cultural transmission of song innovations across entire ocean basins demonstrates a capacity for social learning that is exceptionally rare among non-human animals. Play behavior is widespread among whale species and is another indicator of cognitive complexity. Young humpback whales have been observed surfing ocean swells, rolling seaweed on their fins, and chasing each other in what appears to be playful interaction. Beluga whales are particularly playful, frequently observed blowing bubble rings, playing with objects, and interacting with other species including humans. Young killer whales play with prey items, tossing seals or fish into the air, behavior that may serve both as play and as practice for hunting skills they will need as adults. Sperm whales engage in social rubbing, in which group members press their bodies together and glide against each other, apparently as a form of social bonding. Right whales form surface-active groups during the breeding season, with multiple whales rolling, touching, and vocalizing together in extended social interactions that can last for hours. Evidence for whale intelligence extends beyond social behavior. Killer whales and some other toothed whales have been shown to possess mirror self-recognition, a cognitive ability associated with self-awareness that is found in only a handful of species including great apes, elephants, and corvids. Whale brains are among the largest of any animal, and the brains of sperm whales, at approximately 17 pounds, are the largest of any species that has ever lived. The neocortex of whale brains is highly convoluted and contains specialized spindle cells (von Economo neurons) that in humans are associated with social cognition and emotional processing. The growing understanding of whale intelligence and emotional complexity has significant implications for conservation ethics. If whales possess self-awareness, cultural traditions, and complex emotional lives, it strengthens the moral argument for their protection beyond purely ecological or economic considerations.

One of the most groundbreaking discoveries in cetacean science in recent decades is the extent to which whale behavior is shaped by culture, the social transmission of information and behaviors from one generation to the next. Cultural traditions in whales influence feeding techniques, vocal dialects, migration routes, and social customs, making whales one of only a few animal groups in which culture plays a major role in shaping behavior. The best-documented examples of whale culture come from killer whales. Different killer whale populations living in the same waters but belonging to different ecotypes maintain entirely separate cultural traditions. In the northeastern Pacific, resident killer whales eat fish while transient killer whales eat marine mammals, and the two groups never interbreed despite overlapping ranges. Each ecotype has its own distinctive hunting techniques, vocal dialect, social structure, and even greeting ceremonies when pods meet. These differences are maintained through cultural learning rather than genetic separation, as the two ecotypes are capable of interbreeding but simply do not. Humpback whales provide another compelling example of cultural transmission. Bubble net feeding, the sophisticated cooperative hunting technique in which whales blow bubbles to corral prey, is found in some humpback populations but not others. When individual humpbacks from non-bubble-netting populations observed and learned the technique from experienced practitioners, it spread through social networks, demonstrating horizontal cultural transmission. Similarly, a novel feeding technique called lobtail feeding, in which humpbacks slap the water with their tails before lunging, was first observed in a single individual in the Gulf of Maine in 1980 and has since spread to a significant proportion of the population through social learning. The cultural transmission of humpback whale songs across ocean basins is another striking example. Research in the South Pacific has documented revolutionary changes in humpback songs that originate in the western Pacific and spread eastward across populations over periods of several years, eventually reaching the eastern Pacific. Each population adopts the new song from its western neighbor, creating a cultural wave that spans thousands of miles. Sperm whales in the Pacific Ocean organize themselves into vocal clans based on shared patterns of coda clicks. These clans, which can number in the thousands of individuals, share not only vocal dialects but also behavioral traditions including preferred habitat use, diving patterns, and social behavior. Calves learn their clan's coda dialect from their mothers and other family members, perpetuating these cultural traditions across generations. The existence of culture in whales has important implications for conservation. When a population of whales is lost, the unique cultural knowledge it carries, including knowledge of feeding areas, migration routes, and survival strategies, is lost with it. This means that repopulating an area with whales from a different cultural background may not be as effective as preserving the original population, because the transplanted whales lack the local ecological knowledge that generations of cultural transmission had produced. Conservation strategies must therefore consider cultural diversity within species, protecting not just genetic diversity but also the behavioral traditions that make each whale population unique.