Dolphins in the Amazon river.
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Species Corner
Amazon River Dolphin (Inia geoffrensis)
by Laurie Stepanek
The distinctive pink coloration of the boto, or Amazon river dolphin, makes it easy to distinguish from other odontocetes. Born with dark gray pigmentation, the dolphins become more translucent with age so that blood circulating beneath their skin gives them a vivid pink appearance, especially on the ventral side. Botos living in clear waters tend to have darker pigmentation than those living in turbid waters.
In addition to their unique coloration, botos can be identified by their long beak containing many stiff hairs. Although all dolphins originally have hair, a characteristic of mammals, most lose it soon after birth. Scientists believe that the botos hairs are used as tactile sensory organs. These may help make up for reduced eyesight.
The mouth of Amazon river dolphins is fairly straight with a slight upturn at the corners. They have heterodont dentition, with conical front teeth and molar-like rear teeth. They eat a wide variety of benthic organisms, including catfish. Heavily armored fish and crustaceans can be crushed with the rear teeth.
Echolocation is probably a major tool in food-finding and navigation. Botos have the ability to change the shape of their melons, like beluga whales, from flat to bulbous. Also, Amazon river dolphins are often seen "scanning" - turning their heads 90° to the side. This is possible because their cervical vertebrae are unfused, as in many ancestral dolphin species. Besides turning their necks, botos can paddle one flipper forward while paddling the other backwards.
When prey is scattered, as in high-water seasons, botos are generally seen in singles or pairs. During low-water seasons, when prey is more concentrated, botos congregate in groups of about 15. Most births occur between June and September. Some females have been observed as lactating and pregnant at the same time.
Botos move at a slower pace than most marine dolphins, swimming between 1.6 and 3.2 km/hour on average. They have occasionally been observed leaping above the surface. They rarely dive longer than two minutes at a time.
Living throughout the Amazon and Orinoco River basins in Brazil, Peru, Bolivia, and Venezuela, botos were historically safe from capture in much of their range because of superstitions of the native people. Children born with spina bifida, in which the skull fails to close, appear as if they have a blowhole and are known as "botos babies." Natives feared that harming a boto will cause their children to be born with this disease.
The species name, Inia geoffrensis, is derived from the name used for botos by a native Bolivian tribe, and from the name of a French naturalist, Geoffrey St. Hilaire. St. Hilaire worked for Napoleon Bonaparte to collect zoological specimens, and his boto specimen serves as the type specimen for the species.
The biggest threat to all species of river dolphins now is land development by humans. Hydroelectric dams limit dolphins movements, and pollution causes developmental and other health problems. Some dolphins are captured in fishing nets, or are captured to be put in aquarium displays.
Amazon River Dolphin (Inia geoffrensis)
by Laurie Stepanek
The distinctive pink coloration of the boto, or Amazon river dolphin, makes it easy to distinguish from other odontocetes. Born with dark gray pigmentation, the dolphins become more translucent with age so that blood circulating beneath their skin gives them a vivid pink appearance, especially on the ventral side. Botos living in clear waters tend to have darker pigmentation than those living in turbid waters.
In addition to their unique coloration, botos can be identified by their long beak containing many stiff hairs. Although all dolphins originally have hair, a characteristic of mammals, most lose it soon after birth. Scientists believe that the botos hairs are used as tactile sensory organs. These may help make up for reduced eyesight.
The mouth of Amazon river dolphins is fairly straight with a slight upturn at the corners. They have heterodont dentition, with conical front teeth and molar-like rear teeth. They eat a wide variety of benthic organisms, including catfish. Heavily armored fish and crustaceans can be crushed with the rear teeth.
Echolocation is probably a major tool in food-finding and navigation. Botos have the ability to change the shape of their melons, like beluga whales, from flat to bulbous. Also, Amazon river dolphins are often seen "scanning" - turning their heads 90° to the side. This is possible because their cervical vertebrae are unfused, as in many ancestral dolphin species. Besides turning their necks, botos can paddle one flipper forward while paddling the other backwards.
When prey is scattered, as in high-water seasons, botos are generally seen in singles or pairs. During low-water seasons, when prey is more concentrated, botos congregate in groups of about 15. Most births occur between June and September. Some females have been observed as lactating and pregnant at the same time.
Botos move at a slower pace than most marine dolphins, swimming between 1.6 and 3.2 km/hour on average. They have occasionally been observed leaping above the surface. They rarely dive longer than two minutes at a time.
Living throughout the Amazon and Orinoco River basins in Brazil, Peru, Bolivia, and Venezuela, botos were historically safe from capture in much of their range because of superstitions of the native people. Children born with spina bifida, in which the skull fails to close, appear as if they have a blowhole and are known as "botos babies." Natives feared that harming a boto will cause their children to be born with this disease.
The species name, Inia geoffrensis, is derived from the name used for botos by a native Bolivian tribe, and from the name of a French naturalist, Geoffrey St. Hilaire. St. Hilaire worked for Napoleon Bonaparte to collect zoological specimens, and his boto specimen serves as the type specimen for the species.
The biggest threat to all species of river dolphins now is land development by humans. Hydroelectric dams limit dolphins movements, and pollution causes developmental and other health problems. Some dolphins are captured in fishing nets, or are captured to be put in aquarium displays.
Inia geoffrensis - Amazon river dolphin, Boto, Inia
Looks like they're CITES II. So, if you have the room for them and found a licensed exporter, you can get them with a US importers license on a bonafide licensed animal business.
Size and Weight:
Length: 2 - 2.6 m (6.5 - 8.5'); Weight: females: 80 - 120 kg (180 - 260 lb); males: 120 - 180 kg (260 - 400 lb) (da Silva & Martin 2000).
Habitat:
The boto uses fresh waters of all types as habitat but is not found in estuaries or other saline waters. It is found at water temperatures from 23 - 30 deg C (73 - 86 deg F). It appears to favor microhabitat areas such as confluences, sharp bends, areas below rapids, smaller channels running parallel to the main river, and sandbars, particularly the deeper waters in these areas. In large white water rivers, most of its activity seems to be directed swimming, as though the animals were transiting between patches of the preferred microhabitat areas. (Klinowska 1991, Leatherwood et al. 2000, Culik 2003b)
In the central Amazon basin, large changes in water levels affect the local distribution of botos. A 10 - 15 m (33 - 49') increase in water level during the flood season leads to the inundation of large areas of forest. (The flood season occurs during December - June. Water levels peak in May and June, and reach their lowest levels between September and early November.) Botos move out of the main river into channels and small lakes, and then into the forest itself, as the rising waters flood the forest. It is then able to use both the flooded forest and grasslands, even swimming among the trees. Shallow water is frequently used for feeding. (IWC 2000, Klinowska 1991, da Silva & Martin 2000)
The boto occurs in the Brazilian Shield Amazonian Rivers & Streams and Varzea & Igapo Freshwater Ecosystems Global 200 Ecoregions. (Olson & Dinerstein 1998, Olson & Dinerstein 1999)
Age to Maturity:
Age of females at first birth is estimated to be between 6 - 10 years (IWC 2000).
Females become sexually mature between 1.6 - 1.8 m (5.3 - 5.7') in length. Males appear to reach sexual maturity at body lengths over 2.0 m (6.5'). (Klinowska 1991)
Gestation Period:
The estimated gestation period is 11 months (IWC 2000).
Birth Season:
Calving occurs during the months of May, June, and July, coincident with peak river levels and their initial decline at the start of the dry season. This seasonality means that the female boto's high energy demands near birth and during early lactation are met by increased availability of fish driven from flooded forests by falling water levels and forced back into, and concentrated in, the remaining waterways. (Culik 2003b)
Birth Rate:
Females give birth to a single calf. Inter-birth intervals are typically 4 - 5 years. The annual pregnancy rate of mature females is around 10 - 15%. (IWC 2000)
Early Development:
Lactation appears to be prolonged (well over a year) (Klinowska 1991). Mother and offspring stay together for at least 2.5 years (Montgomery 2000).
Maximum Age:
One animal was still alive after 18 years in captivity; longevity is probably about 30 years (Nowak 1999).
Diet:
The boto is a generalist feeder. Its diet is known to include over 50 species of fish, usually less than 30 cm (1') long, as well as freshwater crabs and river turtles. Its diet varies markedly on a seasonal basis in synchrony with the flood cycle. Its front teeth are peglike, for seizing prey, but the rear teeth are flatter with peaks or cusps, and thus suited to crushing freshwater crabs, river turtles, and armored catfish. Stomach content analysis showed that less than half the fish species the boto eats are commercially important, and these are taken in relatively small quantities. The boto eats 2.7 - 4.5 kg (6 - 10 lb) of fish each day. Feeding is usually done close to shore, in shallow bays, in flooded forests, or where two rivers meet. Although more often a solitary feeder, the boto sometimes forms loose groups that cooperate in herding and attacking schools of fish. (Klinowska 1991, Best & da Silva 1993, Schmidt-Lynch 1994, Montgomery 2000, Burnie & Wilson 2001)
Behavior:
Activity Patterns: The boto's activity is more intense during early morning and late afternoon, when significant movement into lakes from the river has been noted. Weather conditions affect activity, with more dolphins in evidence on cloudy or rainy days. It apparently is non-migratory, in that regular long journeys do not appear to be undertaken. (Klinowska 1991)
One unusual example of dolphins utilizing both the deeper and shallower portions of habitat was reported by Leatherwood et al. 2000. Thirteen boto were observed continuously for 85 minutes in a sharp river bend with a sandbank. The boto appeared to follow a pattern. Calves circled slowly over the shallow water on the sandbank side, alone or in pairs. The larger boto, some of which were presumed to be the calves? mothers, dived and surfaced in deep water near mid-river for up to four minutes, then returned to the shallows, each joining one of the calves. After a brief reunion with the calves, the larger animals would return to the deep water. There was no suggestion that fish were being brought to the calves in the shallows. Rather, this scenario seemed to represent a kind of "nursery," with the microhabitat partitioned to accommodate the needs of both the adults and the young, dependent calves.
Senses: Though its eyes appear small, they are actually, in the skull, as large as those of marine dolphins. Thus the boto can see quite well, except that its bulging cheeks hamper downward views. This is overcome by swimming upside down. On the other hand, in the murky water of some rivers, the boto relies on its sonar. Utilizing its flexible neck, as it swims through the flooded forest, a boto turns its head from side to side, sounding its way through the maze of drowned branches with a series of pulsed clicks at frequencies up to 170 kilohertz. The boto also has sensory bristles on its beak that allows it to feel for food in the river?s depths. (Cetacea, Schmidt-Lynch 1994, Montgomery 2000)
Diving: The boto's dives usually last less than 1 - 2 minutes, but they can last up to 4 minutes. In central Brazil, botos surface very briefly, rarely twice in quick succession, and almost never in a predictable position (da Silva & Martin 2000).
Swimming: The boto is a slow-moving animal that usually swims at 2.4 - 5.1 km/h (1.5 - 3.2 mi/h) with bursts of more than 23 km/h (14 mi/h). It is able to move its head in any direction, due to the unfused vertebrae in its neck. It is exceptionally flexible and maneuverable, able to swim in confined and shallow areas, and among trees in the flooded forest. (Cetacea, da Silva & Martin 2000).
Social Organization:
As is typical for river dolphins, the boto is predominantly solitary, with only 12 - 26% of sightings involving pairs. Larger groups are occasionally seen; e.g., loose aggregations have been observed at feeding areas. Most groups of two are apparently mothers and calves. There do not seem to be seasonal differences in group size.
Density and Range:
Density:
- Estimates of up to 25 individuals/sq km (65 individuals/sq mi) have been made during the dry season when animals are aggregated in the channel (IWC 2000).
- In a study in the Peruvian Amazon, the densities of boto in confluence areas were found to be much greater (by two to six times) than the overall density in the entire river. This was the case for all of the water levels that were sampled (river flows ranging from medium-low to high). (Leatherwood et al. 2000)
- Densities of botos reported from several surveys (Culik 2003b):
* 0.28 individuals/km (0.44 individuals/mi) in a 1200 km (744 mi) section of the Amazon River between Manaus and Santo Antonio de Ica
* 0.25 individuals/km (0.4 individuals/mi) over 130 km (81 mi) on Rio Ichilo, 1.1 individuals/km (1.8 individuals/mi) on Rio Ipurupuru, and 1.0 individuals/ km (1.6 individuals/mi) on Rio Ibare
* 1.12 individuals/km (1.8 individuals/mi). (Tijamuchi River, in Bolivia)
* tributaries: 4.8 individuals/sq km (12.5 individuals/sq mi); areas around islands: 2.7 individuals/sq km (7.0 individuals/sq mi); along main banks: 2.0 individuals/sq km (5.2 individuals/sq mi) ( along 120 km of the Amazon River bordering Brazil, Colombia, and Peru)
Range:
Seasonal movements of botos are related to the migration of fish and the annual flooding cycle of the river. Botos have undefended home ranges, and seasonal movements are probably slight shifts in the boundaries of the core area. Animals from the central Amazon region (Negro and Tocantins Rivers) occupy the same range year-round. (Best & da Silva 1993)
Conservation Status
Human pressures are causing population concerns. Seine and gill nets pose a real threat to dolphins that get caught in them. Also, hydroelectric power stations are causing changes in fish concentrations and the isolation of dolphin populations within river systems. Another problem is that mercury, which is used in refining fluvial gold, is found in high concentrations in the fish the dolphins consume.
CITES-app II, IUCN-vulnerable
Looks like they're CITES II. So, if you have the room for them and found a licensed exporter, you can get them with a US importers license on a bonafide licensed animal business.
Size and Weight:
Length: 2 - 2.6 m (6.5 - 8.5'); Weight: females: 80 - 120 kg (180 - 260 lb); males: 120 - 180 kg (260 - 400 lb) (da Silva & Martin 2000).
Habitat:
The boto uses fresh waters of all types as habitat but is not found in estuaries or other saline waters. It is found at water temperatures from 23 - 30 deg C (73 - 86 deg F). It appears to favor microhabitat areas such as confluences, sharp bends, areas below rapids, smaller channels running parallel to the main river, and sandbars, particularly the deeper waters in these areas. In large white water rivers, most of its activity seems to be directed swimming, as though the animals were transiting between patches of the preferred microhabitat areas. (Klinowska 1991, Leatherwood et al. 2000, Culik 2003b)
In the central Amazon basin, large changes in water levels affect the local distribution of botos. A 10 - 15 m (33 - 49') increase in water level during the flood season leads to the inundation of large areas of forest. (The flood season occurs during December - June. Water levels peak in May and June, and reach their lowest levels between September and early November.) Botos move out of the main river into channels and small lakes, and then into the forest itself, as the rising waters flood the forest. It is then able to use both the flooded forest and grasslands, even swimming among the trees. Shallow water is frequently used for feeding. (IWC 2000, Klinowska 1991, da Silva & Martin 2000)
The boto occurs in the Brazilian Shield Amazonian Rivers & Streams and Varzea & Igapo Freshwater Ecosystems Global 200 Ecoregions. (Olson & Dinerstein 1998, Olson & Dinerstein 1999)
Age to Maturity:
Age of females at first birth is estimated to be between 6 - 10 years (IWC 2000).
Females become sexually mature between 1.6 - 1.8 m (5.3 - 5.7') in length. Males appear to reach sexual maturity at body lengths over 2.0 m (6.5'). (Klinowska 1991)
Gestation Period:
The estimated gestation period is 11 months (IWC 2000).
Birth Season:
Calving occurs during the months of May, June, and July, coincident with peak river levels and their initial decline at the start of the dry season. This seasonality means that the female boto's high energy demands near birth and during early lactation are met by increased availability of fish driven from flooded forests by falling water levels and forced back into, and concentrated in, the remaining waterways. (Culik 2003b)
Birth Rate:
Females give birth to a single calf. Inter-birth intervals are typically 4 - 5 years. The annual pregnancy rate of mature females is around 10 - 15%. (IWC 2000)
Early Development:
Lactation appears to be prolonged (well over a year) (Klinowska 1991). Mother and offspring stay together for at least 2.5 years (Montgomery 2000).
Maximum Age:
One animal was still alive after 18 years in captivity; longevity is probably about 30 years (Nowak 1999).
Diet:
The boto is a generalist feeder. Its diet is known to include over 50 species of fish, usually less than 30 cm (1') long, as well as freshwater crabs and river turtles. Its diet varies markedly on a seasonal basis in synchrony with the flood cycle. Its front teeth are peglike, for seizing prey, but the rear teeth are flatter with peaks or cusps, and thus suited to crushing freshwater crabs, river turtles, and armored catfish. Stomach content analysis showed that less than half the fish species the boto eats are commercially important, and these are taken in relatively small quantities. The boto eats 2.7 - 4.5 kg (6 - 10 lb) of fish each day. Feeding is usually done close to shore, in shallow bays, in flooded forests, or where two rivers meet. Although more often a solitary feeder, the boto sometimes forms loose groups that cooperate in herding and attacking schools of fish. (Klinowska 1991, Best & da Silva 1993, Schmidt-Lynch 1994, Montgomery 2000, Burnie & Wilson 2001)
Behavior:
Activity Patterns: The boto's activity is more intense during early morning and late afternoon, when significant movement into lakes from the river has been noted. Weather conditions affect activity, with more dolphins in evidence on cloudy or rainy days. It apparently is non-migratory, in that regular long journeys do not appear to be undertaken. (Klinowska 1991)
One unusual example of dolphins utilizing both the deeper and shallower portions of habitat was reported by Leatherwood et al. 2000. Thirteen boto were observed continuously for 85 minutes in a sharp river bend with a sandbank. The boto appeared to follow a pattern. Calves circled slowly over the shallow water on the sandbank side, alone or in pairs. The larger boto, some of which were presumed to be the calves? mothers, dived and surfaced in deep water near mid-river for up to four minutes, then returned to the shallows, each joining one of the calves. After a brief reunion with the calves, the larger animals would return to the deep water. There was no suggestion that fish were being brought to the calves in the shallows. Rather, this scenario seemed to represent a kind of "nursery," with the microhabitat partitioned to accommodate the needs of both the adults and the young, dependent calves.
Senses: Though its eyes appear small, they are actually, in the skull, as large as those of marine dolphins. Thus the boto can see quite well, except that its bulging cheeks hamper downward views. This is overcome by swimming upside down. On the other hand, in the murky water of some rivers, the boto relies on its sonar. Utilizing its flexible neck, as it swims through the flooded forest, a boto turns its head from side to side, sounding its way through the maze of drowned branches with a series of pulsed clicks at frequencies up to 170 kilohertz. The boto also has sensory bristles on its beak that allows it to feel for food in the river?s depths. (Cetacea, Schmidt-Lynch 1994, Montgomery 2000)
Diving: The boto's dives usually last less than 1 - 2 minutes, but they can last up to 4 minutes. In central Brazil, botos surface very briefly, rarely twice in quick succession, and almost never in a predictable position (da Silva & Martin 2000).
Swimming: The boto is a slow-moving animal that usually swims at 2.4 - 5.1 km/h (1.5 - 3.2 mi/h) with bursts of more than 23 km/h (14 mi/h). It is able to move its head in any direction, due to the unfused vertebrae in its neck. It is exceptionally flexible and maneuverable, able to swim in confined and shallow areas, and among trees in the flooded forest. (Cetacea, da Silva & Martin 2000).
Social Organization:
As is typical for river dolphins, the boto is predominantly solitary, with only 12 - 26% of sightings involving pairs. Larger groups are occasionally seen; e.g., loose aggregations have been observed at feeding areas. Most groups of two are apparently mothers and calves. There do not seem to be seasonal differences in group size.
Density and Range:
Density:
- Estimates of up to 25 individuals/sq km (65 individuals/sq mi) have been made during the dry season when animals are aggregated in the channel (IWC 2000).
- In a study in the Peruvian Amazon, the densities of boto in confluence areas were found to be much greater (by two to six times) than the overall density in the entire river. This was the case for all of the water levels that were sampled (river flows ranging from medium-low to high). (Leatherwood et al. 2000)
- Densities of botos reported from several surveys (Culik 2003b):
* 0.28 individuals/km (0.44 individuals/mi) in a 1200 km (744 mi) section of the Amazon River between Manaus and Santo Antonio de Ica
* 0.25 individuals/km (0.4 individuals/mi) over 130 km (81 mi) on Rio Ichilo, 1.1 individuals/km (1.8 individuals/mi) on Rio Ipurupuru, and 1.0 individuals/ km (1.6 individuals/mi) on Rio Ibare
* 1.12 individuals/km (1.8 individuals/mi). (Tijamuchi River, in Bolivia)
* tributaries: 4.8 individuals/sq km (12.5 individuals/sq mi); areas around islands: 2.7 individuals/sq km (7.0 individuals/sq mi); along main banks: 2.0 individuals/sq km (5.2 individuals/sq mi) ( along 120 km of the Amazon River bordering Brazil, Colombia, and Peru)
Range:
Seasonal movements of botos are related to the migration of fish and the annual flooding cycle of the river. Botos have undefended home ranges, and seasonal movements are probably slight shifts in the boundaries of the core area. Animals from the central Amazon region (Negro and Tocantins Rivers) occupy the same range year-round. (Best & da Silva 1993)
Conservation Status
Human pressures are causing population concerns. Seine and gill nets pose a real threat to dolphins that get caught in them. Also, hydroelectric power stations are causing changes in fish concentrations and the isolation of dolphin populations within river systems. Another problem is that mercury, which is used in refining fluvial gold, is found in high concentrations in the fish the dolphins consume.
CITES-app II, IUCN-vulnerable
i will get a pic from my mom she took a river tour of the amazon and has pics of them in the wild
