| Of the five freshwater species of dolphins in
the world, the pink Amazon River dolphin, Inia geoffrensis, or "bufeo
colorado” as they are known in Peru and “botos" as they known in
in Brazil, are considered to be the most intelligent.
These friendly, sensitive, mammals with a brain capacity 40% larger
than that of humans, who have lived in harmony with the people of the Amazon
and its tributaries for centuries, now face extinction in some tributaries.
What was considered to be one of the least threatened species of dolphins
20 years ago, has now become one of the most endangered species due to
the accelerated and commercialized rape of the Amazon basin and the destruction
of the South American tropical rainforest.
No one knows the actual number of Inia geoffrensis that live
n the Amazon basin, but according to the reseach and studies that Roxanne
Kremer has conducted in the Upper Basin of the Peruvian Rainforest, 150
kilometers upstream of Iquitos, Peru, the number of pink dolphins from
18 years ago has risen from eight pink dolphins on the Yarapa River to
35 to 45. Ms. Kremer counted the dolphins in July 1998. ISPTR believes
that her work with the Peruvian Forest Police to protection both species
of river dolphins, and empowering the local peoples of their rights and
use of the law, there has been less illegal commercial fishing and logging
in the area, thus saving the natural habitat of the land and aquatic life.
The struggle to save these treasured beings as an important link in
an ecosystem -- currently being encroached upon by industrialized forces
-- is being spear-headed by the non-profit International Society for the
Preservation of the Tropical Rainforest (ISPTR), whose first globally known
project PARD, the Preservation of the Amazonian River Dolphin.
Click here to download a 1/2 minute video that represents
a plea for support from the Pink Dolphins and other animals of the Rainforest.
Biology of River Dolphins
Social Habits
Ecological factors strongly influence social behavior. Because Amazon
River dolphins do not have any known natural predators -- other than humans
-- they do not need to live in large groups, or "pods," protection as many
dolphin species.
Inia geoffrensis (pink dolphins) engage in solitary hunting/feeding
strategies during the high water season when their prey fishes disperse
into the floodplains. At other times, they are found in small "family"
groups of 5-8 animals which seem to be led by a dominant adult male. At
river confluences, we have seen as many as 35 pink dolphins cooperatively
herding and banking fish, often in association with the gray dolphins.
Sotalia fluviatlis (gray dolphins) are strongly gregarious animals
and manifest strong social ties with their own kind. Given that they seem
to practice a polyandrous breeding system and females tend to be a bit
larger than males, they may have a matriarchal social order.
| Pink Dolphin Physical Description
Size: 2.5 to 3 meters (8.25 ft to 9.75 ft) and 90 kilograms (200
lbs.).
Males are generally larger.
Habitat and Distribution: Tributaries and main rivers of the
Orinoco River systems of South America. They tend to gather at confluences
of rivers.
Reproduction: Calves can be born between July and September,
but in front of Dolphin Corners, our lodge becomes a nursery for calves
during December-February. Calves are born about 75 cm (30 in.) long, and
weighing just over 1 kg. (2.2 lbs.) after a gestation period believed to
be nine to twelve months. Sexual maturity in males is reached when they
are about two meters (7 ft.) long, and females at 1.7 meter (5.5 ft.) at
an unknown age |
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Inia geoffrensis
(Pink Dolphin)
|
Diet: Crustaceans, catfish and small fresh water fish. A unique
characteristic of Inia geoffrensis is the unfused vertebrae in its
neck, which allows for the 180-degree head turn, giving them greater flexibility
in floodplain forests, grassland, tributaries and shallow waters. They
have a hump on their back instead of a dorsal fin.
Coloration: The reasons for the unique coloration of Inia
geoffrensis are poorly understood, but the presence of capillaries
near the surface of the skin probably accounts for much of its characteristic
pink flush. Other factors may include age of the animal, chemical disposition
of the water (especially iron content), and the temperature of the water.
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Mother with baby |
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| Ancestors: Ancestors of Inia geoffrensis
were a relatively successful marine group, but were displaced during the
Miocene period by the appearance of more advanced delphinids.
Inia
may have entered the Amazon from the Pacific Ocean approximately 15 million
years ago, or from the Atlantic Ocean between 1.8 million and 5 million
years ago. Their long beaks (often lined with tiny hairs), small eyes,
disproportionately large flippers and highly flexible bodies -- once considered
"primitive" features -- are now recognized as specialized adaptions to
a complex environment.
Soltalia fluviatlis is a warm-water coastal species distributed
from the eastern coast of Central America down along the northeastern coast
of South America. No one knows for sure when some of these delphinids began
to occupy and adapt to freshwater river systems. They are one of the few
delphinid species which can move freely between fresh, brackish, and marine
waters.
Intelligence: The intelligence of Amazon River dolphins has not
been extensively tested. Their encephalization quotient (the ratio of brain
mass to body weight) compares favorably with that of the bottlenose dolphin
(Tursiops). The gray dolphins tend to be more "cautious" than the
pink dolphins, perhaps because of their small size and very delicate skin.
On the other hand,
Inia is known for its highly developed sense
of curiousity and it rapidly associates with man in a variety of serious
and playful ways. |
|
Dolphins and People: Given that these animals are threatened
with extinction in certain tributaries, we do not actively seek or encourage
overtly "friendly" contact with the Amazon River dolphins. Their chances
of survival are greatly enhanced if they remain suspicious of human beings
and maintain a certain distance. |
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Roxanne interacting with dolphin |
Incidental mortality due to fishing nets is very common throughout
the Amazon Basin, although it is impossible to estimate the total number
of net-related deaths. Gill nets, used by commercial fisherman, are regarded
as the most dangerous to the dolphins.
Contrary to popular opinion, all dolphins are capable of behaving
agressively toward human beings at certain times and under certain conditions.
There are a number of reports of pink dolphins pushing people to the shore
after their canoes had capsized. The dolphins figure prominently in the
local mythology and their reputation varies from one tributary to another.
In some locations, the pink dolphins are considered as unpredictable brujos
(wizards), and, in other locations, they are benign and helpful semi-divine
beings. The gray dolphins are usually regarded as "sacred" animals, especially
by various Indian tribes. Up until recent times, the dolphins and people
who live along the Amazon River existed in harmony with each other. It
has only been within the past three decades, more or less, that the psychic
relationship between the people and dolphins has been fractured as a result
of deforestation and habitat degradation. ISPTR/PARD is dedicated to protecting
these unique mammals and their tropical rainforest ecosystem, thus healing
this time-honored relationship, not only for the dolphin's sake but, also,
for the sake of our own human spirit. |
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To purchase a scientific paper on Inia geoffrensis authored by
Roxanne Kremer, click here. |
