Pteronura brasiliensis (Gmelin, 1788)

Voss, Robert S. & Fleck, David W., 2017, Mammalian Diversity And Matses Ethnomammalogy In Amazonian Peru Part 2: Xenarthra, Carnivora, Perissodactyla, Artiodactyla, And Sirenia, Bulletin of the American Museum of Natural History 2017 (417), pp. 1-1 : 1-

Pteronura brasiliensis (Gmelin, 1788)

Figure 15D

VOUCHER MATERIAL (TOTAL = 1): Nuevo San Juan (MUSM 11173).

OTHER INTERFLUVIAL RECORDS: Río Yavarí (Salovaara et al., 2003), Río Yavarí-Mirím (Salovaara et al., 2003), San Pedro (Valqui, 1999).

IDENTIFICATION: Giant otters are externally and cranially unmistakable ( Husson, 1978; Emmons, 1997) and no conspicuous morphological differences have been reported among the Amazonian populations traditionally referred to Pteronura brasiliensis brasiliensis . Apparently, the same mtDNA phylogroup—the “Amazon/Orinoco/Guianas” clade of Pickles et al. (2011)— extends from western Amazonia to French Guiana (the type locality; Husson, 1978), and craniodental measurements of our single voucher specimen ( table 13 ) compare closely to those of nearly topotypic material from Surinam ( Husson, 1978: table 47).

ETHNOBIOLOGY: The Matses name for the giant otter is onina. It is probably onomatopoetic and does not occur in other Panoan languages. There are no archaic synonyms or overdifferentiated varieties.

The giant otter is of no economic importance to the Matses. They are never kept as pets.

The spirit of a giant otter can make children ill if their parent looks at one. Matses with children formerly made great efforts to avoid seeing giant otters, but now that the Matses frequently travel by boat, it is almost impossible to avoid seeing them. Giant otter sickness causes high fever (as does contagion by Neotropical otters), which can be treated with particular medicinal plants (“giant otter medicine”). Other plants used to treat illness caused by Neotropical otters are also used to treat contagion by giant otters.

MATSES NATURAL HISTORY: The giant otter has a head like a paca’s and teeth like a jaguar’s. It has a light-colored patch on the front of its neck. It has thick whiskers, a flat tail, short legs, and webbed feet. It is much larger than the Neotropical otter.

Giant otters are always near water, in ox-bow lakes, rivers, and large streams, but not in small streams, except near their mouths. They also catch fish in flooded forest.

Giant otters are diurnal. They sleep at night in an undercut bank or some other sheltered place along a river, stream, or lake. They spend much of the day chasing fish, swimming very quickly. They travel far, swimming along rivers and streams. They can swim underwater and are always poking their heads out of the water. They fish for a long time in deep river curves. They play in the water chasing each other.

They make clearings on riverbanks and lakeshores where they eat the fish they have caught. Such clearings are free of all vegetation and look as if they had been swept. Giant otters come back to the same clearings to eat. One clearing is close to their den, and others are further off, often on the bank of a deep curve of a river, or at the mouth of a stream. Such clearings are littered with fish bones and scales and smell of rotting fish.

When giant otters see people, they dive and swim away underwater. If they have young, they become fierce when they see people, baring their teeth and growling. When one imitates their call, they come calling.

Giant otters live in packs of five to 20 individuals. The females give birth to two young in a burrow, the entrance of which is in the undercut bank of a stream. Males catch fish and take them to feed the young while the female stays with the young. The den stinks like rotten fish and has many flies. Only the female with young sleeps in the den. When the young are strong enough to swim, they abandon the den and sleep in other places (not burrows).

Giant otters fish in the presence of dolphins. No predators kill giant otters.

Giant otters have a loud squealing call that the Matses imitate as “waa waa waa.”

Giant otters eat mostly fish, all types of fish including inchishchued ( Brycon spp. [ Characidae ]), bëdichued ( Leporinus spp. , Schizodon spp. [ Anostomidae ]), wolffishes ( Hoplias spp. [Ery-

thrinidae]), armored catfish, and large pimelodid catfishes. They also eat crabs.

REMARKS: Matses interviews about giant otters include most of the essential natural history facts about this remarkable species, including its diurnal activity, piscivorous diet, highly social behavior, almost predator-free existence, construction of vegetation-free campsites on river banks, exclusive use of a birthing den by females and newborn young, and aggressive defense of family groups against human intruders ( Duplaix, 1980; Carter and Rosas, 1997; Duplaix et al., 2015). The Matses observation that males provision females with nursing young is not reported in the literature we consulted. Their interesting observation that giant otters fish in the presence of dolphins hints at, but does not explicitly confirm, the possibly cooperative association between Pteronura and Inia suggested by Defler (1983).

Figures

FIG. 15. Adult skulls of five sympatric mustelid species illustrating taxonomic differences in size and shape: Galictis vittata (A, MUSM 15157), Eira barbara (B, MUSM 13149), Mustela africana (C, AMNH 61813), Pteronura brasiliensis (D, AMNH 74431), Lontra longicaudis (E, AMNH 98589). All illustrated specimens are from eastern Peru, but only MUSM 13149 and MUSM 15157 are from the Yavarí-Ucayali interfluve.