Amazon Pink River Dolphins
The pink Amazon river dolphin, alternately Bufeo, Bufeo Colorado (pink), Boto, is a freshwater river dolphin endemic to the Orinoco, Amazon and Araguaia/Tocantins River systems of Brazil, Bolivia, Peru, Ecuador, Colombia and Venezuela. The largest of the river dolphins, the pink river dolphin is not to be confused with the Tucuxi or gray river dolphin (Sotalia fluviatilis), whose range overlaps that of the Amazon pink river dolphin but is not a true river dolphin since they also range into the ocean. The pink dolphin lives exclusively in the freshwater of the Amazon River basin. Because pink river dolphins have unfused neck vertebrate, they are able to turn 180 degrees. The Amazon pink river dolphin looks like the grey dolphin, but the pink dolphins are bigger, and, instead of a dorsal fin, they have a hump on their back. This serves as good field mark to identify them as they surface for air. Another way to tell them apart even at night time is by the sound they make when the surface for air. The pink reiver dolphins sound like a smoker's cough as they expell and intake air. The gray river dolphin makes a more smooth sound when they surface. The heads of both dolphin species are also different. The gray river dolphin as a typical head and snout similar to ocean dolphins. The Amazon pink river dolphin had long beak and large and round forehead. The pink river dolphin has been listed as endangered by the International Union for Conservation of the Nature (IUCN) due to pollution, overfishing, excessive boat trafficking and habitat loss. The brain of the pink river dolphin is 40% larger than a human brain.
The IUCN lists various other names to describe the Amazon pink river dolphin, these include: Amazon Dolphin, Boto Vermelho, Boto Cor-de-Rosa, Bouto, Inia, Pink Dolphin, Wee Quacker, Pink Freshwater Dolphin, Pink Porpoise, Tonina and Encantado. The pink Amazon river dolphin is particularly common in lowland rivers with extensive floodplains. During the annual rainy season these rivers flood large areas of forests and marshes along their banks. The pink Amazon River dolphin specializes in hunting in these habitats, taking advantage of its unusually flexible neck and spinal cord to maneuver among the underwater tree trunks, and using its long snout to extract prey fish from hiding places in hollow logs and thickets of submerged vegetation.
When the water levels drop, the pink dolphins move either into the main river channels or into large lakes in the forest, and take advantage of the concentrated prey in these reduced water bodies.
Amazon pink river dolphins do not have any known natural predators, hence they do not need to live in large groups, or "pods," for protection as many other dolphin species. 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 individulas. Gray river dolphins are more gregarious animals and manifest strong social ties with their own kind. Females tend to be a bit larger than males, they may have a matriarchal social order.
Pink river dolphins have relatively small eyes and while eyes are of little use in the murky water of the Amazon, the dolphins rely on echolocation to navigate and find their prey. Pink dolphins are constantly emitting sounds of frequencies higher than what a human ear can detect. These sounds waves collide with objects around the dolphin and bounce back providing information on the distance, size and nature of the objects the dolphin is travelling through. The bulky forehead is thought to act as receptor of bouncing sounds. Recording of pink river dolphin vocalizations played at frequencies audible by humans reveal a series of sharp humming sounds combined with shrieks, clicks and chirps. Dolphins seem to be in constant communication as they travel in the murky waters of the Amazon and its tributaries. Pink river dolphins are believed to use sound while fishing. Pink dolphins appear to corner small schools of fish and blast high frequency sound that stuns the fishes momentarily making them vulnerable to the fishing dolphins. Their long beaks and maneuverability of their head allows them to pick the fish from tangled aquatic vegetation.
Pink Amazon River Dolphins: The Legend
In traditional Amazon River folklore, at night, a pink Amazon river dolphin becomes a handsome young man who seduces girls, impregnates them, and then returns to the river in the morning to become a pink Amazon river dolphin again. This pink dolphin shapeshifter is called an encantado. It has been suggested that the myth arose partly because pink dolphin genitalia bear a resemblance to those of humans. Others believe that the myth served (and still serves) as a way of hiding the incestuous relations which are quite common in some small isolated communities alongside the river. In the area, there are tales that it is bad luck to kill a pink Amazon river dolphin. Legend also states that if a person makes eye contact with a pink Amazon river dolphin, that person will have nightmares for the rest of his/her life. Local legends also state that the pink dolphin is the guardian of the Amazonian manatee, and that, should one wish to find an Amazonian manatee, one must first make peace with the Amazon pink river dolphin.
Associated with these legends is a culture of use of various fetishes such as dried pink dolphin eyeballs and genitalia. The use of these fetishes may or may not be accompanied by the intervention of a priest. Although sold as boto objects, a recent study has shown that, despite the claim of the seller and the belief of the buyers, none of these fetishes are derived from the boto of pink river dolphin. They are derived from the grey river dolphin, which are most likely harvested along the coast and the Amazon River delta, and then are traded up the Amazon River. In inland cities that are far from the coast, many if not most of the fetishes are derived from domestic animals such as sheep and pigs.
The pink amazon river dolphin is particularly common in rivers with extensive floodplains such as the Samiria River. Photo: kevin Schafer
In contrast to the gray river dolphin, pink river dolphins have a hump on their backs. They can travel in family groups or often individually. Photo: Pablo Puertas
Gray river dolphins are smaller in size and more gregarious. While the coloration can be similar to some pink river dolphins, the dorsal fin is distinctive and is a field mark used to quickly tell the two species apart. In the Pacaya-Samiria National Reserve both species can be seen fishing side by side. Photo: Pablo Puertas
