Kategorie: News
A Very Special Courtship
For animals of this size, even the most intimate of acts is a logistical challenge. Whales and dolphins must find each other underwater - without solid ground, without hands, and with the constant need to surface regularly to breathe.
The nature conservation organization Whale and Dolphin Conservation (WDC), which has been studying the social and reproductive behavior of these animals for years, is among those documenting how different species solve this problem.
Before mating takes place, many species invest considerable effort in courtship. Male humpback whales sing elaborate songs, often lasting several minutes, that change over the course of a season and are “echoed” by several animals at the same time. Other large whales rely on spectacular body language: breaching—in which these animals, weighing several metric tons, launch themselves almost entirely out of the water - or powerful tail slaps are part of the repertoire males use to attract attention or demonstrate to rivals who is in control of a group.
Dolphins take a more cooperative approach. In some species, several males temporarily form alliances to circle a female ready to mate and keep rivals at bay - a behavior closely linked to their complex social structure. Added to this are acoustic signals such as clicks and whistles, as well as conspicuous swimming patterns, which males use to attract attention.
A Brief Act with a Long Build-Up
As elaborate as the courtship may be, the actual mating act in dolphins is surprisingly brief. It often lasts only a few seconds but is repeated multiple times within a short period. In large whale species, by contrast, mating takes significantly longer - which is hardly surprising given their size and the inability to hold onto one another. Unlike many land mammals, whales and dolphins are constantly in motion during this process, which makes it even more difficult.
Reproductive strategies also vary greatly between species. While humpback whales are promiscuous and both sexes mate with multiple partners, narwhals tend to form stable pair bonds. Orcas, on the other hand, live in matriarchal groups in which females often remain with their mothers for life and reproduce within these close-knit social structures.
After successful fertilization, a long gestation period begins, lasting between about 10 and 18 months, depending on the species. Toward the end of pregnancy, many females specifically seek out sheltered, warmer waters to give birth to their calves there. Almost all whale and dolphin species share a distinctive trait: the calves are born tail-first rather than head-first, as is typical for most mammals. If the head were to emerge first, there would be a risk that the calf would drown before its body is fully delivered and it can reach the water’s surface to take its first breath.
Immediately after birth, the mother begins providing intensive care: She helps the calf reach the water’s surface, nurses it, and protects it during its first months of life - in social species such as dolphins, often with the support of other group members.
Further information:
Danny Groves (WDC), in Discover Wildlife
Smithsonian Ocean Portal