The humpback whales have well-known geographic and temporal patterns: during winter and spring they remain at low latitudes to breed and to calve, and in summer they use higher latitudes to feed. The species occurs in both hemispheres and in all oceans and is divided into different populations. The population that migrates to the Brazilian coast between July and October belongs to the Breeding Stock A.
The size of an adult can reach 16 meters and weigh up to 40 tons, while a calf is born with approximately 4 meters and weighing 1 ton. The pectoral fins can measure up to 1/3 of their total length, and one of the reasons why the scientific name of the species is Megaptera novaeangliae, since “Megaptera” means big wings in Greek, while “novaeangliae” is associated with the first place where the species was registered - New England (United States of America).
Credits: Daniel Danilewicz
Humpback whales prefer warm waters closer to the coast to give birth, where their calves have a more favorable environment to spend the first days of their lives. Males also migrate to tropical regions looking for females available to mate. After copulation, the female goes to the sub-Antarctic regions to feed and return to Brazil for the birth of its calf, with a gestation period of approximately 1 year. In the first months of its life, the calf is usually observed in resting behavior while feeding on its mother's nutritious milk to grow and prepare for its first 4000 km migration, a distance that separates the coast of Bahia from South Georgia and Sandwich Islands, where the population feeds. After 1 year, in which the calf suckles and learns to feed itself, it returns to Brazil accompanying its mother, and ready to start its journey alone. The only social link established by these animals is between mother and calf, while the calf is dependent on its mother.
In addition to the breaches and tail and pectoral slaps performed by humpback whales, producing sounds underwater that can be used for example to call attention, males produce a set of complex and standardized sounds known as "song". Singing occurs predominantly in the breeding areas, and thus it is believed to be associated with reproductive behavior or to attract females willing to mate or to keep out potential competitors. All males in the same population emit the same song as if it was a "hit", but each breeding season the song changes and progressively evolves into a new "hit", and all males learn the new stretches with each other and continue singing in the same way.
It is worth noting that humpback whales remain fasting off the Brazilian coast, save some exceptions recorded in southeastern Brazil. For this reason, they need to eat the best they can during the summer, accumulating a layer of fat that can reach 15 cm thick, which will be converted into energy for the rest of the year. Humpback whales feed by filtering small crustaceans known as krill (Euphasia superba) through plates composed of keratin that descend from the top of the mouth and work as curtains called baleen. The ventral folds that run from the navel to the mandible extend like an accordion to increase the volume of water with food inside the mouth.