Social structure and play Belugas are highly sociable and they regularly form small groups, or pods, that may contain between two and 25 individuals, with an average of 10 members. Pods tend to be unstable, meaning individuals tend to move from pod to pod. Radio tracking has even shown belugas can start out in one pod and within a few days be hundreds of miles away from that pod. Beluga whale pods can be grouped into three categories, nurseries (which consist of mother and calves), bachelors (which consist of all males) and mixed groups which contain both sexes. Many hundreds and even thousands of individuals can be present when the pods join in river estuaries during the summer. This can represent a significant proportion of the total population and is when they are most vulnerable to being hunted. They are cooperative and frequently hunt in coordinated groups. Often individuals will surface and dive together in a synchronized manner, in a behavior known as milling. In captivity, they can be seen to be constantly playing, vocalising and swimming around each other. In one case, one whale blew bubbles, while the other one popped them. There have also been reports of beluga whales copying and imitating one another, similar to a game of Simon-says. There have also been reports of them displaying physical affection, via mouth to mouth contact. They also show a great deal of curiosity towards humans and frequently approach the windows in the tanks to observe them. Belugas also show a great degree of curiosity towards humans in the wild, and frequently swim alongside boats. They also play with objects they find in the water; in the wild, they do this with wood, plants, dead fish and bubbles they have created. In captivity, mothering behavior among belugas depends on the individual. Beluga calves will often require sustenance and care from both their mothers but also other belugas who serve as
alloparents in their community. Beluga calves are often nursed by their mothers for the first year of its life before they become a juvenile. During this same stage in their lives, they also require their mothers to draft them through the stream, as the newborn beluga is likely to be an uncoordinated swimmer. Between the ages of 2 and 5, the beluga becomes a juvenile and is likely to start seeking independence from its mother. However, it will still continue to maintain its involvement in its social circle. Among free-ranged belugas, it has been observed that calves will often form bonds with each other while their mothers were out foraging. These social groups of immature calves have been referred to as "kindergartens", and furthermore it has been noticed that an alloparent, referred to as an "aunt", can attend to these groups. A study in 2014 revealed that most beluga whales swam in formation with both parents and alloparents. They frequently swim at speeds between , although they are able to maintain a speed of 22 km/h for up to 15 min. Belugas swim on the surface between 5% and 10% of the time, while for the rest of the time they swim at a depth sufficient to cover their bodies. although they are capable of diving to greater depths. Individual captive animals have been recorded at depths between 400 and 647 m below sea level, while animals in the wild have been recorded as diving to a depth of more than 700 m, with the greatest recorded depth being over 900 m. A dive normally lasts 3 to 5 minutes, but can last up to over 20 minutes. In the shallower water of the estuaries, a diving session may last around two minutes; the sequence consists of five or six rapid, shallow dives followed by a deeper dive lasting up to one minute. During a dive, these animals will reduce their heart rate from 100 beats a minute to between 12 and 20. Lastly, the beluga's muscles contain high levels of the protein
myoglobin, which stores oxygen in muscle. Myoglobin concentrations in belugas are several times greater than for terrestrial mammals, which help prevent oxygen deficiency during dives.
Diet , the staple diet of belugas from Alaska Belugas play an important role in the structure and function of marine resources in the
Arctic Ocean, as they are the most abundant toothed whales in the region. They are opportunistic feeders; their feeding habits depend on their locations and the season. For example, when they are in the
Beaufort Sea, they mainly eat
Arctic cod (
Boreogadus saida) and the stomachs of belugas caught near Greenland were found to contain
rose fish (
Sebastes marinus),
Greenland halibut (
Reinhardtius hippoglossoides) and
northern shrimp (
Pandalus borealis), while in Alaska their staple diet is
Coho salmon (
Oncorhynchus kisutch). In general, the diets of these cetaceans consist mainly of fish; apart from those previously mentioned, other fish they feed on include
herring,
capelin,
smelt,
cod,
salmon,
flatfish,
sculpin,
lingcod, and
eulachon. Belugas feed mainly in winter as their blubber is thickest in later winter and early spring, and thinnest in the fall. Inuit observation has led scientists to believe that belugas do not hunt during migration, at least in Hudson Bay. The diet of Alaskan belugas is quite diverse and varies depending on season and migratory behavior. Belugas in the Beaufort Sea mainly feed on staghorn and shorthorn sculpin,
walleye pollock,
Arctic cod,
saffron cod and
Pacific sand lance. Shrimp are the most common invertebrate eaten, with octopus,
amphipods and
echiurids being other sources of invertebrate prey. The most common prey species for belugas in the Eastern Chukchi Sea appears to be shrimp, echiurid worms, cephalopods and
polychaetes. The largest prey item consumed by beluga whales in the Eastern Chukchi Sea seems to be saffron cod. Beluga whales in the Eastern Bering Sea feed on a variety of fish species including saffron cod,
rainbow smelt, walleye pollock,
Pacific salmon,
Pacific herring and several species of flounder and sculpin. The primary invertebrate consumed is shrimp. The primary prey item in regard to fish species for belugas in Bristol Bay appears to be the five species of salmon, with sockeye being the most prevalent. Smelt is also another common fish family eaten by belugas in this region. Shrimp is the most prevalent invertebrate prey item. The most common prey items for belugas in Cook Inlet appear to be salmon, cod and smelt. Animals in captivity eat 2.5% to 3.0% of their body weight per day, which equates to . Like their wild counterparts, captive belugas were found to eat less in the fall. Foraging on the seabed typically takes place at depths between , although they can dive to depths of in search of food. --> Their flexible necks provide a wide range of movement while they are searching for food on the ocean floor. Some animals have been observed to suck up water and then forcefully expel it to uncover their prey hidden in the silt on the seabed. As their
teeth are neither large nor sharp, belugas must use suction to bring their prey into their mouths; it also means their prey has to be consumed whole, which in turn means it cannot be too large or the belugas run the risk of it getting stuck in their throats. They also join into coordinated groups of five or more to feed on
shoals of fish by steering the fish into shallow water, where the belugas then attack them.
Reproduction Estimations of the age of sexual maturity for beluga whales vary considerably; the majority of authors estimate males reach sexual maturity when they are between nine and fifteen years old, and females reach maturity between eight and fourteen years old. The average age at which females first give birth is 8.5 years and fertility begins to decrease when they are 25, eventually undergoing menopause, and ceasing reproductive potential with no births recorded for females older than 41. There is a slight difference on the sexual maturation period between males and females. The male beluga whales take seven to nine years to become sexually mature, while the females take four to seven years. Female belugas typically give birth to one calf every three years. During the mating season, the testes of belugas double in weight. Testosterone levels increase, but seems to be independent of copulation. Copulation typically takes place between 3 and 4 AM. Calves are born over a protracted period that varies by location. In the Canadian Arctic, calves are born between March and September, while in
Hudson Bay, the peak calving period is in late June, and in
Cumberland Sound, most calves are born from late July to early August. Births usually take place in bays or estuaries where the water is between 10 and 15 °C. The newborn calves nurse under water and initiate
lactation a few hours after birth; thereafter, they feed at intervals around an hour. The milk contains about 92
cal per
ounce. The calves remain dependent on their mothers for nursing for the first year, when their teeth appear. Hybrids have been documented between the beluga and the narwhal (specifically offspring conceived by a beluga father and a narwhal mother), as one, perhaps even as many as three, such hybrids were killed and harvested during a sustenance hunt. Whether or not these hybrids could breed remains unknown. The unusual dentition seen in the single remaining skull indicates the hybrid hunted on the seabed, much as walruses do, indicating feeding habits different from those of either parent species.
Communication and echolocation Belugas use sounds and
echolocation for movement, communication, to find breathing holes in the ice, and to hunt in dark or turbid waters. In special circumstances, beluga whale sounds have been reported to resemble human speech. A Japanese researcher claimed that he taught a beluga to "talk" by using these sounds to identify three different objects, offering hope that humans may one day be able to communicate effectively with sea mammals. Belugas communicate using high frequency sounds; their calls can sound like bird songs, so belugas were nicknamed "canaries of the sea". Like the other toothed whales, belugas do not possess
vocal cords and the sounds are probably produced by the movement of air between the nasal sacks, which are located near to the blowhole. They use their vocalisations for echolocation, during mating and for communication. They possess a large repertoire, emitting up to 11 different sounds, such as cackles, whistles, trills and squawks. There is debate as to whether cetacean vocalizations can constitute a language. A study conducted in 2015 determined that European beluga signals share physical features comparable to vowels. These sounds were found to be stable throughout time, but varied among different geographical locations. The further away the populations were from each other, the more varied the sounds were in relation to one another. == Habitat and distribution ==