Life History
Very little is known about the life histories of beaked whales. The oldest one ever recorded was 84 years for a male Baird’s beaked whale, and the oldest recorded female Baird’s beaked whale is 54 years. For all other beaked whale species studied, the highest recorded age is between 27 and 39 years. Sexual maturity is reached between seven and 15 years of age in Baird’s beaked whales and northern bottlenose whales. Gestation varies greatly between species, lasting 17 months for Baird’s beaked whales and 12 months for the northern bottlenose whale. There are currently no data available on their reproductive rates.
It is difficult to determine group size of beaked whales, due to their inconspicuous surfacing behavior. Groups of beaked whales, defined as all individuals found in the same location at the same time, have been reported as ranging from one to 100 individuals. Nevertheless, some populations’ group size has been estimated from repeated observations. For example, northern and southern bottlenose whales (H. ampullatus and H. planifrons), Cuvier’s beaked whales and Blainville’s beaked whales (Mesoplodon densirostris) have a reported maximum group size of 20 individuals, with the average ranging from 2.5 to 3.5 individuals. Berardius species and Longman’s beaked whales (Indopacetus pacificus) are found in larger groups of up to 100 individuals.
Not much information is available about group composition of beaked whales. Only three species have been studied in any detail: northern bottlenose whales, Blainville’s beaked whales, and Baird’s beaked whales. Female northern bottlenose whales appear to form a loose network of social partners with no obvious long-term associations. In contrast to females, some male northern bottlenose whales have been repeatedly recorded together over several years, and possibly form long-term associations. Studies of Blainville’s beaked whales have revealed groups usually consist of a number of females, calves and/or juvenile animals. These whales are assumed to live in "harem-like" groups, where several females and young are accompanied by a single male. Baird’s beaked whales are known to occur in multiple male groups, and in large groups consisting of adult animals of both sexes.
Read more about this topic: Beaked Whale
Famous quotes containing the words life and/or history:
“With liberty and pleasant weather, the simplest occupation, any unquestioned country mode of life which detains us in the open air, is alluring. The man who picks peas steadily for a living is more than respectable, he is even envied by his shop-worn neighbors. We are as happy as the birds when our Good Genius permits us to pursue any outdoor work, without a sense of dissipation.”
—Henry David Thoreau (1817–1862)
“The history of the Victorian Age will never be written: we know too much about it.”
—Lytton Strachey (1880–1932)