Studies need to be undertaken in areas where the mammals are not habituated to humans in order to verify possible differences between populations with and without contact with humans. They feed mainly on fish, aided by echolocation. The time of divergence corresponds to the time the Amazon and Araguaia-Tocantins river basins became separated, implying vicariant speciation. It became the first newly recognized variety in nearly 100 years. Sounds were categorised according to duration and the presence of non-linear phenomena such as subharmonics or biphonation. There is still more work to do. However, commercial fishermen around the park have been killing them because they sometimes steal fish from nets. The inhabited section of the Araguaia River probably extends over about 1500 km out of a total length of 2110 km. (2014). This truly fascinating species of mammal only received recognition as a separate species from the Amazon River Dolphin in 2014. +61 8 7120 8600 (International) One aspect of the behavior of Araguaia River Dolphin, distinct from other dolphins in the Amazon basin, is its ability to navigate in extremely shallow waters, pushing their bodies over shallow sandbanks. More than half of the studied animals were able to be identified as individuals. Instituto Araguaia has tested several methods to study these dolphins since the species was first described in January 2014, by INPA and University of Dundee. The most common sound made was a short two-component call, produced by baby dolphins when they approached their mothers after a short separation. Underwater recordings were taken at the same time as video footage, resulting in 15.7 hours of acoustic material. Instituto Araguaia has already adopted Inia araguaiensis as a flagship species, using it in presentations, the Internet, and media interviews to generate public interest for the protection of the species and its habitat. Here are some facts about the Amazon River Dolphin. The Araguaian river dolphin (Inia araguaiaensis) is a close relative of the Amazon river dolphin (Inia geoffrensis). In June 2015 Brazilian biologist Julia Furstenau Oliveira began field work for a master's thesis at the University of Freiburg (Germany) in association with Instituto Araguaia and University of Brasilia, on methods for population censuses of river dolphins. The Araguaia River comes from Goiás-Mato Grosso south borders. [3], However, I. araguaiaensis is still not recognized as a separate species by the Committee on Taxonomy of the Society for Marine Mammalogy, the largest international association of marine mammal scientists in the world. (Aquatic mammals are mammals that have adapted to live in water). A major constraint in studying river dolphin behaviour is that, unlike their marine relatives, they do not perform conspicuous surface displays, making identification of individuals in the field very difficult. They have a much greater vocal range than previously thought. that they live in muddy water. 'Cosmos' and 'The Science of Everything' are registered trademarks in Australia and the USA, and owned by The Royal Institution of Australia Inc. T: 08 7120 8600 (Australia) echo-location to find Like other river dolphins, I. araguaiaensis has a prominent forehead and a much longer snout than those of most marine dolphins, as well as smaller eyes than marine dolphins. “We can’t say what the evolutionary story is yet until we get to know what sounds are produced by other river dolphins in the Amazon area, and how that relates to what we found,” May-Collado adds. “Their vocal repertoire is very diverse.”. The Amazon River Dolphin is a freshwater dolphin. Dolphins are members of a group of marine mammals known as … Like all known species of river dolphin, many individuals consider this beautiful creature highly threatened. Unfortunately, destruction of its native habitat continues at a rather prodigious rate, with no apparent end in sight. leaves fresh water in the winter and moves to the coastal waters along They rely on heavily on their They Diagnostic osteological differences were also reported. The Araguaia River Dolphin ( Inia araguaiaensis or Araguaian boto) is one of the rarest and most endangered dolphins in the world. The recognition of I. araguaiaensis as a distinct species is still debated. “There are a lot of obstacles like flooded forests and vegetation in their habitat, so this signal could have evolved to avoid echoes from vegetation and improve the communication range of mothers and their calves,” she says. [3] Major rapids in the lower Tocantins River (into which the Araguaia River flows) are thought to have contributed to isolating the two species, as the Pará River (into which the Tocantins flows) connects with the Amazon River. The truly remarkable Araguaian River Dolphin represents a newly discovered species of river dolphin. Rundle Mall SA 5000, Australia, 55 Exchange Place, The middle and lower basin of the river is in the Xingu-Tocantins-Araguaia moist forests ecoregion. The southernmost population of the species is a small group of isolated individuals in the Tocantins river above the Serra da Mesa dam. The river dolphin genus has been little studied, so the researchers expected to find more acoustic signals than those previously recorded – but, even so, the results were a big surprise. It was explored in part by Henri Coudreau in 1897. Follow, If you are a nature enthusiast, if you care about our amazing planet and want to be part of our cause. [3] The ecology of its habitat has been adversely affected by agricultural, ranching and industrial activities, as well as by the use of dams for hydroelectric power. Shooting is common, but around protected areas like Cantão, where the sound of a gun might attract park rangers, some fishermen have taken to putting out poisoned bait for dolphins. dolphins in their appearance. The Committee made these comments regarding the decision to not include I. araguaiaensis as an independent species: "Inia araguaiaensis, was described by Hrbek et al. An Amazon River Dolphin is also often referred to as a Pink River Dolphin, a Boto or a Bufeo. Their appearance is much like the Boto and Bolivian River Dolphins with a long snout, and a large rounded forehead. They have a dorsal ridge rather than a fin. This area is an integral part of the Amazon biome; however, the Araguaia River is not a tributary of the Amazon. Unfortunately, there are only 1000-5000, which puts them on the endangered list. We've surveyed lakes throughout the park and found that in the dry season all of Cantão, dolphins concentrate in a few large lakes whose period of isolation is shorter than most. extiction of a marine mammal in 50 years. The additional knowledge and images generated by this project will greatly strengthen our ability to do so. Araguaian River Dolphin The Araguaian lives only in the Araguain River basin has been declared a new species! Back in the lab, the sound recordings were first subjected to a spectrographic analysis. [3], Inia araguaiaensis (Araguaian river dolphin), Inia boliviensis (Bolivian river dolphin), Pontoporia blainvillei (La Plata dolphin), †Lipotes vexillifer (baiji or Yangtse river dolphin), The estimated times of divergence with I. boliviensis, P. blainvillei and L. vexillifer are 2.9, 12.0 and 16.2 Ma ago, respectively. May-Collado speculates that the riverine habitat has been a driver in the evolution of the intermediate frequency. This makes it one of the few known such creatures on earth. Credit: Danita Delimont/ Getty Images. It has a total length of approximately 2,627 km. The combined watershed of Araguaia and Tocantins rivers (named the Araguaia Tocantins Basin) covers approximately 9.5% of Brazil's national territory. Inia araguaiaensis. This is the first record of the They are only found in the water of the Amazon River, the Orinoco River and the Araguaia River. We have continued this aerial survey ever since. Its principal tributary is the Rio das Mortes, which rises in the Serra de São Jerônimo, near Cuiabá, Mato Grosso, and is navigable to Pará. However, it does not yet have an official classification with the. At Cosmos, we publish stories from people who cherish evidence-based knowledge and showcase the really exciting scientific, technological and engineering breakthroughs that are happening right here, right now. Home to Whale Facts and Dolphin Facts from River Dolphins. The Tocantins River habitat is fragmented by six hydroelectric dams, so the population there is at particular risk. Because their aquatic environment is often turbid, their vision is not as well developed. All whistles and pulsed calls were selected for further examination using a program called ARTwarp. Your email address will not be published. We developed and tested a method to count the dolphins from the air using drones and balloon cameras, and through field trials established that this was far more accurate than the standard method of counting dolphins from a boat.