Migration. Photograph: Fredrik BromsHumpbacks are widely distributed and can be found in all oceans of the world. Most humpback populations undertake extensive annual migrations from high-latitude summer feeding grounds to low-latitude winter breeding grounds and back. Their migrations are among the longest known for any mammal on Earth and the distance between breeding and feeding areas can be up to 8000 km or more.
During their stay in high-latitudes, most of their time is spent on feeding and building up fat stores while they hardly eat during migration or in low-latitude mating grounds. On mating grounds, males are competitive and are well known for their complex songs. Sexual maturity is thought to be reached at 4-5 years of age and females usually produce a calf every two to three years.
Associations between individuals vary somewhat depending on social context but do not last long, with the exception of mother and calf pairs who stay together approximately one year. Calves travel together with their mothers back to the northern feeding grounds and typically return to the same feeding ground that they were first brought to as a calf by their mother later in life, meaning that individuals return to the same regions over periods of years. Some whales may overwinter in high latitudes.