Humpback whales generally swim in pods; the basic social group consists of the cow (female), a single calf, and the "escort" male. Most Humpback behaviors seen in the Hawaiian Islands are related to courtship and mating, which places the cow at the center of socialization during the winter months. Escorts do little to help raise the calves because their primary attention is directed to mating and fending off other males.
When two or more escort males are accompanying a cow, mating competition can become intense. Male Humpbacks have been witnessed using glancing rostrum blows, lateral fluke swipes, bubble streaming, head lunging, and various vocalizations during mating challenges. Scars and gouges are common amongst adult males; some display dorsal fins that have been sheared off during past confrontations. This brutal competition puts serious pressure on cows and their calves, often forcing them to expend great energy avoiding rushes and collisions from challenging escorts. These competitions can range in size from three whales to two dozen and are an amazing sight to witness.
Although female Humpbacks are capable of producing sounds, only the males produce highly structured 'songs' which feature distinctive melodies and themes. Scientists have found that all the males in a Humpback population sing the same song at any one time. The song pattern changes over time, but all the males still sing the same new song. The songs can be heard more then 20 miles away and may last up to 20 minutes.
Humpbacks don't have vocal chords; their songs are most likely produced by circulating air through the tubes and chambers of their respiratory system. No air escapes during the concerts and they are almost always performed on breeding grounds. The males usually sing suspended deep below the surface, their long pectoral fins jutting rigidly from their sides. Scientists have documented that the majority of the whales approaching singers were other males. Since the ensuing meetings often end in a competitive tussle, it is now believed the whales are issuing threats rather than singing love songs.