Mating and Reproduction
Reproductive histories of females.
Calving intervals for individually identified females ranged between
1 to 5 years. Calving rates (calves per mature female per year)
were estimated as .58 based on Hawaii
sightings of calves and .37 based on sightings in Alaska (Baker,
Perry & Herman, 1987). The lower figure in Alaska
was likely attributable to calf mortality during the first year
of life.
Mating system of the humpback whale.
The social organization and behaviors of male humpback whales in
the winter ground had characteristics similar to that a lekking
system seen in some insects, ungulates and birds (Herman & Tavolga,
1980). In a lekking system, males aggregate in a mating ground known
as a lek, and females visit the lek to mate with the males. The
males will engage in vigorous behavioral and sometimes vocal displays
from an individual territory they hold within the lek. More dominant
males occupy the territories preferred by the females, and these
males will perform most of the breeding activity. There are some
important differences between the mating system of the humpback
whale and a classic lek, however; most noticeably, male humpback
whales do not appear to be territorial, as described above for a
classic lek. However, many other characteristics are similar to
a lekking system, such as the assembly of humpbacks on their winter
mating grounds, synchronicity of reproductive activities between
males and females, an operational sex ratio of 2:1 favoring males
on the breeding grounds, single parental care of young, the fact
that no feeding occurs on the mating grounds, and the possible sexual
display nature of whale song.
Baker,
C. S., Perry, A., and Herman, L. M. (1987).
Reproductive histories of female humpback whales Megaptera novaeangliae
in the North Pacific. Marine Ecology Progress Series 41,
103-114.
Herman, L. M. and Tavolga, W. N. (1980). The
communication systems of cetaceans. In: L. M. Herman (Ed.), Cetacean
behavior: Mechanisms and functions (pp. 149-209). New York:
Wiley Interscience.
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