Sousa teuszii.
Usually seen in groups of two to ten, hump-backed dolphins
do not seem to develop strong social bonds. Researchers speculate,
however, that the animals are part of larger groups that maintain
their identities over time. A distinct breeding season has
not been observed, although calving increases during the summer
months.
Unlike Tursiops, Sousa do not bowride. The surfacing styles
of the two genera are different. Hump-backed dolphins fully
expose their rostrum and melon, unlike most bottlenose dolphins,
then sharply roll and arch their backs to accentuate their
humps. To dive, they flex far forward and often expose their
flukes, with a distinctive notch between them, before disappearing
beneath the surface.
Feeding on nearshore, estuarine, and reef fish, the dolphins
are seldom spotted more than one kilometer offshore. Some
have even been reported in rivers, though it is not known
if they reside in them or were merely visiting.
One of the best known stories of dolphin-human interaction
occurs at Cap Timiris in western Africa. There, Atlantic hump-backed
dolphins cooperate with Mauritanian fishermen to catch mullet.
When the fishermen spot a school of the fish, they beat on
the water with sticks to attract the dolphins. The dolphins
then drive the mullet into the fishermen's nets along the
beach.
Accidental drowning in fishing nets and occasional hunting
for human consumption were historically the greatest threats
to the hump-backs. A new concern has arisen with the development
of African and Asian countries as mangrove and estuarine habitat
is destroyed. These dolphins have not been studied in great
detail, so the health of the population is questionable.
Jefferson, T.A., S. Leatherwood, and M.A. Webber. FAO Species
Identification Guide: Marine Mammals of the World. FAO. Rome,
1993
Leatherwood, S., and R. Reeves. The Sierra Club Handbook
of Whales and Dolphins. Sierra Club Books. San Francisco.
1983. By Laurie Stepanek
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