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Mummal Rev. 1997, Volume 27, NO. 1, 1-26. Printed In Grcar Britain
Biology and conservation of the Giant Otter Pteronura
brasiliensis
S. K. CARTER*? and F. C. W. ROSAS*
*Institute Nacional de Pesqirisas da Amaz6nia (INPA), Laboratbrio de Mamiyeros
Aqubticos, Caixa Postal 478, Manaus, AM 6901 I-970, Brazil
ABSTRACT
The Giant Otter Pferonuru brasifiensis (Zimmermann, 1780) is endemic to South America, distributed throughout the Orinoco, Amazon and La Plata River basins and numerous localities in the
Guyanas. This otter is the largest member of the family Mustelidae, clearly distinguished from other
South American otter species by morphological and behavioural characteristics. Large-scale pelt
hunting in the 1950s and 1960s led to the classification of the species as ‘vulnerable’ by the World
Conservation Union (IUCN, 1990). Habitat degradation and destruction now present the largest
threat to remaining populations. The current distribution of the Giant Otter is presented, emphasizing recent information collected in the Amazon Basin. Morphology, systematics, habitat,
behaviour, diet, predation, competition, reproduction, development and physiology are discussed.
New data on habitat use and preference, behaviour and diet in northern Amaz6nia are included, and
recommendations for future conservation measures are made. Because of the decimation of the
Giant Otter in its southern distribution and the habitat destruction occurring in the remainder of its
range, we recommend that this species be elevated to ‘endangered’ status in the IUCN Red Data
Book.
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INTRODUCTION
The Giant Otter Pteronura brasiliensis (Zimmermann, 1780) formerly inhabited most freshwater
streams of South America, from Venezuela to Argentina (Eisenberg, 1989). By the early 1970s, pelt
hunters had decimated many populations, leading to the classification of the Giant Otter as a vulnerable species in the World Conservation Union (IUCN) Mammal Red Data Book (Thornback &
Jenkins, 1982). Remaining populations of Giant Otters are threatened by increasing development in
the Amazon, Orinoco and La Plata River basins where exploitation of timber, minerals, fossil fuels
and hydroelectric power is rapidly destroying and degrading their habitat.
Despite the Giant Otter’s current ‘vulnerable’ status (IUCN,1990). relatively little is known of
its biology and ecology. Tum of the century explorers OF the Amazon region made brief observations of large groups of otters, and some qualitative descriptions of diet, reproductive behaviour and
early development of captive animals were published in the 1960s and 1970s. More recently field
studies have been carried out in Suriname (Duplaix, 1980), Guyana (Laidler, 1984), Brazil
(Schweizer, 1992) and Pe,m (Brecht-Munn & MUM, 1988; Schenck & Staib, 1992; Staib &
Schenck, 1994). These studies are generally limited to dry-season observations of a few animals or
groups over a relatively short period of time. Information on movement patterns, habitat use and
diet during the flooded season is scarce due to the labour-intensive nature of observing aquatic
mammals in areas of extensive seasonal flooding.
In this paper we compile information from available literature, unpublished documents and personal interviews to present a comprehensive review of the biology and current status of this species.
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Current address: Washington Cooperative Fish and Wildlife Research Unit, School of Fisheries, Box
357980, University of Washington, Seattle, WA 98 195-7980, USA.
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S. K . Carter and F. C. W‘. Rosas
New data collected by the authors in north central AmazBnia are included in sections on habitat,
behaviour and diet. Based on all information reviewed by the authors, specific measures are recommended to conserve remaining Giant Otter populations in South America.
MORPHOLOGY
The Giant Otter is known by the common name ‘ariranha’ (Portuguese), ‘arirai, perro de agua, lobo
del n o grande, lobito de cola ancha, lob0 gargantilla, lobo corbata and nutria gigante’ (Spanish). It
is the largest of the four Latin American otters. Its total body length typically ranges from 1.5 to
1.8 m in males and 1.5 to 1.7 m in females (Hershkovitz, 1969; Mondolfi, 1970; Duplaix, 1980).
Historically, considerably larger measurements were reported: Cabrera & Yepes (1940) state that
old males with a total body length of 2.20 m have been hunted; Santos, (1984 [originally published
in 1945 by F. Briguiet & Cia., Rio de Janeiro]) personally observed skins longer than 2 m and cites
a skin from Amazonas state which measured 2.40 m; and Hams (1968) cites a personal communication referring to a 1959 book by the Brazilian Ministry of Education and Culture which gives a
total body length of 2.40 m for the largest specimens hunted. The present authors were unable to
examine the reference reported in Hams (1968). These large measurements have not been confirmed by recent data and we suggest that they probably represent older males, as indicated by
Cabrera 8c Yepes (1 940) which may have been more common prior to the commencement of heavy
hunting in the 1950s. Other measurements are clearly taken from skins (Santos, 1984) which likely
overestimate whole body lengths and may in addition be stretched or otherwise distorted. Body
weight generally ranges from 26 to 32 kg for males and 22-26 kg for females (Duplaix, 1980); the
heaviest individual on record weighed 34 kg (75 lbs) (Fountain, 1902). In the water, the Giant Otter’s heavy body is propelled by its powerfil bilaterally flanged tail, -0.454.65
m in length, and
extensively webbed feet (Foster-Turley, Macdonald & Mason, 1990).
Skull, jaw, dentition, baculum and limb measurements of Giant Otters are given by Hams
( 1968), Bjork (1 970), Van Zyll de Jong (1 972), Robertson (1 976) and Husson ( 1978). The Giant
Otter is the only species of otter in which the rhinarium is completely haired (Foster-Turley et al.,
1990) and each individual can be identified from birth by the irregular pattern of whitish or creamcoloured hairs on its chin and throat (Fig. 1). The thick coat is composed mainly of short soft guard
hairs, ~8 mm long; there is very little underfur (Foster-Turley et al., 1990). Fur colour varies from
fawn to reddish brown or darker, appearing almost black when wet (Harris, 1968; Husson, 1978).
Two anal scent glands are used in temtorial marking and may be involuntarily contracted if the
animal is startled (Duplaix, 1980; Laidler, 1984; S.K.Carter, personal observation).
Vision has not been studied in the Giant Otter, but studies of the North American River Otter
Lutra canadensis and Sea Otter Enhydra l u t h have found these species to be emmetropic or
slightly myopic in both air and water (Ballard, Sivak & Howland, 1989; Murphy et al., 1990).
Above water, Giant Otters are capable of recognizing observers at distances of -50 m (Duplaix,
1980). Under water, Giant Otters hunt primarily by sight (Schweizer, 1992) and very likely have an
accommodative range similar to that confirmed for the Sea Otter and North American River Otter
which is 54-59 dioptres, several times greater than what has been reported for other mammal species (Ballard et al., 1989; Murphy et al., 1990). This accommodation is believed to result from the
well-developed ciliary and iridial muscles acting to change the curvature of the lens upon immersion (Walls, 1963; Ballard et al., 1989; Murphy et a[., 1990). The external morphology of
Pteronura’s brain, specifically an enlarged coronal gyrus, suggests increased sensitivity of the
facial vibrissae (Radinsky, 1968), which appears to assist Giant Otters hunting in murky waters
(Schweizer, 1992). Hearing is acute, and well-developed scroll bones in the nasal chambers indicate an excellent sense of smell (Duplaix, 1980).
Although the Giant Otter’s physical characteristics are distinctive, it has been confused in the
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Biology of the Giant Otter
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Fig. 1. Captive adult female Giant Otter Preronura brarifiensis. National Institute of Amazon Research,
Manaus, Brazil (Photo by F. C. W. Rosas).
past with two other mustelids. The Neotropical Otter Lutru longicuudis is of similar build and colouring, but the distinctive neck marking of the Giant Otter and the difference in size and behaviour
patterns between the two species should clearly separate them to the informed observer (see Hams,
1968; Mason & Macdonald, 1986; Chanin, 1985). Until the early 1800s, the Giant Otter was also
frequently conhsed with the well-known Sea Otter because of their similar size (both species are
significantly larger than all other Lutrinae). Clear differences in their physical characteristics, habitats and ranges soon distinguished the two species (Harris, 1968).
SYSTEMATICS
Nomenclature of the Giant Otter has been discussed by several authors (see Hams, 1968; Husson,
1978). In recent works, authorship of the species is most widely given to Gmelin, 1788. Based on
the discussion presented in Husson (1978), we employ here the name Pteronuru brusiliensis
(Zimmermann, 1780).
The extinct species Sutheriumpiscinuriu from the late Pliocene (v;a1.5-3 million years ago) has
been suggested as an ancestor of the Giant Otter based on skull, dental and skeletal features (Bjork,
1970). Robertson ( 1976) also noted strong similarities between Sutherirrm and Pteronuru based on
his examination of the humerus and podia1 elements of Sutherium sp. from Florida.
Of the 13 extant otter species in the subfamily Lumnae, family Mustelidae (following Mason,
1990), Van Zyll de Jong (1972) found Pteronuru to be most closely associated with the Smooth
Otter ( L u m perspiciffatu,formerly Lutrogufeperspiciffatu)of south and south-east Asia. This
controversial finding was based on an analysis of sM1, dentition, feet, m a m a e and vertebrae.
Recently, Davis (1978) divided the subfamily Lutrinae into three tribes based on baculum shape
and vocalizations. He placed Pteronrrru brnsifiensis in the tribe Aonychini along with the Asian
Small-Clawed Otter Aonyx cinereu, Cape Clawless Otter Aonyx cupensis, Congo Clawless Otter
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S. K. Carter and F. C. W. Rosas
Aonyx congica, Smooth Otter and Sea Otter. These morphologically diverse species are united by
having no affection call, an inflected contact call, baseball shaped bacula and a preputial button
(except in Enhydra).They all live in social groups and, with the exception of Enhydra, pairing is
generally for life and the male participates in cub care.
A subspecies, Pteronura brasiliensis paranensis (Rengger 1830), inhabiting the Parana and
Paraguai Rivers, has been described, but its validity is questionable. The type specimen was very
similar in general appearance to P. brasiliensis. It would likely have been regarded as a variety of
P. brasiliensis had it not apparently had abnormal dentition, possessing only four molariforrn teeth
on each side of the upper jaw instead of the normal five (Harris, 1968). IUCN (1 992) states that the
colour of the throat patch differs in this subspecies, but this is not mentioned as a subspecific characteristic in Harris’ review of the species. Other differentiating characteristics given for
P. brasiliensis paranensis are smaller size. a more gregarious nature, larger teeth and a broader
skull (Harris, 1968). No recent taxonomic studies have validated the subspecific status of
P. brasiliensisparanensis; hence we consider Pteronura a monotypic genus in this review.
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DISTRIBUTION AND ABUNDANCE
The Giant Otter originally inhabited most of South America, ranging from the Guyanas across
Venezuela and Colombia, south to northem Argentina and west to the Andes (Hams, 1968;
Thornback & Jenkins, 1982). Although the latitudinal range of the Giant Otter remains large, intense pelt hunting greatly reduced their numbers and completely eliminated populations in many
localized areas. The current population of Giant Otters may be as low as 1000-3000 individuals
(Brecht-Munn & MUM, 1988). However, this is probably an underestimate as -500
inhabit the
southern portion of the upper Paraguai River basin of Brazil alone (Schweizer, 1992).
The country-by-country distribution of Giant Otters reported here is based on published accounts and sightings by the authors. Reliable information received in 1993 and 1994 through personal interviews and written communication from regional authorities is also included where it
updates published information and/or identifies newly discovered areas of habitation. The published source follows the personal communication in the case of the former. The presence of Giant
Otters has been confirmed in each location within the last 25 years unless otherwise noted.
Suriname, Guyana and French Guiana (Fig. 2)
The last major Giant Otter strongholds are probably Suriname, Guyana and French Guiana
(Chehebar, 1990). In Suriname, Giant Otters are considered common on almost all rivers in the
forested central and southern parts of the country (H. A. Reichart, personal communication).
Duplaix (1980) sighted over 250 individuals in a survey o f the country from 1976 to 1979. She
verified their presence on the following rivers (only major tributaries are listed here): the Corantijn
and the Zuid River of its Lucie tributary, the Nickerie and its Maratakka tributary, the Wayombo,
the Coppename and its Coesewijne, Tibiti and Tangnimama tributaries; and the Commewijne and
its Cassewenica. Cottica and Perica tributaries. She received reports indicating that they also inhabit the Marowijne, Saramacca and Suriname Rivers.
In Guyana, Giant Otters were reported from near the city of Morawhanna in the north-west and
from the Mahaica and Abary Rivers by Melquist (1984). Laidler (1984) studied four resident family
groups in her study site in Demerara District encompassing parts of Russel Lake and the Mahaica
River and its Lama, Maduni and Carabice Creeks (Laidler, 1984). Healthy populations of Giant
Otters inhabit the upper Mazaruni Basin and the upper Potaro River (above Kaieteur Falls) (Laidler
& Laidler, 1983). They were present in the Karmambo area of the northern Rupununi in 1988 (N.
Gordon, personal communication) and there are unconfirmed reports of healthy populations in
Spectacle Lake on the northern Rupununi River (Laidler & Laidler, 1983). The species has been
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Biology of the Giant Otter 5
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Fig. 2. Distribution of Giant Otters in Guyana and Suriname, showing rivers and areas inhabited by Giant
Otters as cited in text. Squares indicate study site of Duplaix (1980) on Kaboeri Creek in Suriname and of
Laidler ( I 984) on Russel Lake in Guyana.
heavily hunted on the southern Rupununi because of its proximity to Brazil and the consequent ease
of smuggling pelts across the border. Giant Otters also inhabit the Mashivean and Morewan Rivers,
tributaries of the upper Essequibo in southern Guyana (Melquist, 1984).
No specific information is available from French Guiana, but the Giant Otter is presumed to be
widely distributed in the interior (Melquist, 1984).
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Venezuela and Colombia (Fig. 3)
In a review of the status of the Giant Otter in Venezuela, Mondolfi & Trebbau (1978) report that
their numbers have been greatly depleted along the coast and in the mid and lower Orinoco and its
tributaries. Relict populations may still exist in parts of the Orinoco delta, and in the lower Orinoco
Basin Giant Otters are reported from the lower C a m and its tributary the Nichare, where they are
apparently very scarce due to hunting (Mondolfi & Trebbau (1978). The IUCN (1982) reports that
Giant Otters inhabit Canaima National Park in the Caroni Basin and Melquist (1984) reports
sightings on the Caroni and Paragua Rivers (above the Gun hydroelectric dam).
In the mid Orinoco Basin, Mondolfi & Trebbau (1978) report that Giant Otters have been nearly
exterminated on the Aguaro River (in the Aguaro-Guariquito National Park), although Rios (1987)
maintains they still inhabit this area. Giant Otters were recorded fiom the Apure River near Puerto
Nutrias in 1976 by Mondolfi & Trebbau (1978) and later from the same area by Melquist (1984).
Small groups are also reported from restricted tributaries of the Portuguesa River, including the
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6 S.K. Carter and F. C. W. Rosas
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Fig. 3. Distribution of Giant Otters in Venezuela and Colombia, showing rivers and areas inhabited by
Giant Otters as cited in text. Circles indicate cities or the approximate centre of protected areas.
Cojedes (Mondolfi & Trebbau, 1978). They are very scarce on the Capanaparo, Claro and
Cunaviche Rivers, but were present in 1976 on Caiio Macanillal, a tributary of the latter (Mondolfi
& Trebbau, 1978). A specimen was collected from the Cinaruco River in the late 1960s (Handley,
1976), but inquiries in 1978 indicated that populations on the Cinaruco had been exterminated
(Mondolfi & Trebbau, 1978). This is disputed by Rios (1987). In the Ventuari Basin of the upper
Orinoco, Giant Otters are reported from the Manapiare and Parucito Rivers and the Yutaje and
Cerro Yavi areas just north of the watershed. They are considered scarce on the upper Ventuari
(Mondolfi & Trebbau, 1978). Giant Otters are reported to be very scarce in several rivers of the
upper Orinoco as far as the Casiquiare Canal because of intense hunting, but they were present on
the upper Esmeralda River in 1976 (Mondolfi & Trebbau, 1978). Melquist (1984) reports a recent
sighting on the upper Orinoco near Platanal.
In Colombia intense hunting has nearly exterminated Giant Otter populations in vast areas of the
Orinoco and Amazon basins (Mondolfi, 1970). Defler (1986) found ~ 3 groups
0 of Giant Otters
inhabiting the Tomo, Tuparrito and Tuparro Rivers and Quinvaza Creek of the El Tuparro National
Park in north-eastem Colombia and he believes they are present on the Bita River just north of the
park. They were recorded from the Putumayo and a tributary of the Javari (near Leticia) in the early
1970s (Donadio, 1978). A total of 24 otters were counted on the Miritiparena River in 1976 and
they also occur on the Duda River in Sierra de la Macarena National Park and in Arauca Sanctuary
(Melquist, 1984). Chehebar (1990) suggests that many other Giant Otter populations exist in Colombia, but this is undocumented.
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Biology of the Giant Otter
7
Brazil (Figs 4 and 5)
In Brazil Giant Otters inhabit the Amazon and upper Paraguai River basins and restricted areas of
million km' ofsparsely populated land
the Atlantic Forest. The Brazilian Amazon encompasses -5
and probably supports significant populations of Giant Otters in remote areas, although this is unconfirmed due to the logistical problems of surveying an area this large. In the Negro River Basin,
Giant Otters inhabit the Unini River and may be present on the upper Jau and Pauini Rivers within
Jau National Park (C. E. M. Miller, personal communication; G. H. RebClo, personal communication; IUCN, 1982). They were present on the Itapari and Itaparazinho Creeks (near Boiaqu),
Catrimani River and Urancoera River (tributaries of the Branco River) in 1991, 1994 and 1988,
respectively (C. M. Carvalho, personal communication; V. Py-Daniel, personal communication;
Colares, 1990). Therc are reports of Giant Otters on the lower Parima (V. Py-Daniel, personal communication). Groups also inhabit the Xixuau, Xiparani and Mucucuau Creeks of the lower Jauaperi
River (S. K. Carter & F. C. W. Rosas, personal observation; N. Gordon, personal communication).
In the Solim6es River basin, Giant Otters were observed on the upper Javari and the Japuri Rivers
in 1981 and 1984, respectively (V. Py-Daniel, personal communication). In the Purus Basin, they
are reported to inhabit the Rio Acre Ecological Station (IUCN, 1982).
In the Madeira River basin, Giant Otters were present in 1979 on the Canuml, the Aripuanf and
its Branco tributary (C. R. Bueno, personal communication; K. Yuyama, personal cornmunication); and groups were sighted on the Roosevelt River in 1992 (J. Ferraz, personal communication;
G. M. Santos, personal communication). Sizable populations are reported from the upper Jamari
(c.Colares, personal communication) and a group was sighted on Paraiso Creek of the Ji-Paranii in
1987 (P. Martuscelli, personal communication). In the Uaturnf River basin, Giant Otters are present
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Fig. 4. Distribution of Giant Otters in the Brazilian Amazon, showing rivers and areas inhabited by Giant
Otters as cited in text. Square indicates study site of the authors on Xixuau Creek. Circles indicate cities
or the approximate centre of protected areas. Dashed line indicates state boundary of Maranhio.
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Fig. 5. Distribution of Giant Otters in central and southern Brazil, showing ri\ers and areas inhabited by
Giant.Otters as cited in text. Circles indicate cities or the approxlmate centre of protected areas.
in the area of Balbina hydroelectric dam (F. N. Armond, personal communication; Colares, 1988)
and groups were observed on the Pitinga River in 1994 (A. A. Souza, personal communication;
Colares, 1988). Sizable populations are reported from the upper Jatapu River (C. Colares, personal
communication).
Further east in the Amazon ICTCN (1982) reports Giant Otters in Tapajos National Park and lquC
Ecological Station. and George et al. ( 1988) state that they are probably present on remote tributaries of the Tapajos. Giant Otters were reported in the Rio Trombetas Federal Biological Reserve by
IUCN (1982), and groups were observed on a tributary of the upper Trombetas and on the CuruaUna River in 1985 and 1982, respectively, (V.Py-Daniel, personal communication; Salvo Souza,
1982). Groups were also sighted on the mid Xingu in 1993 (V. Py-Daniel, personal communication). IUCN (1982) reports Giant Otters inhabit the Lago Piratuba Federal Biological Reserve and
Araguaia National Park and groups still inhabit the Paraim River of the upper Tocantins basin (C.
L. MagalhBes, personal communication; Lima & Lima, 1984). Almeida, Pimentel, & Pimentel
(1992) indicate that Giant Otters are present in MaranhBo state but give no specific distribution information.
Giant Otters also inhabit the south-eastem and central western regions of Brazil, but they are
believed to be extinct in southern Brazil (Rosas et al., 1991). Giant Otters are now repopulating
almost all rivers in the upper Paraguai River basin, known as the Pantanal, because of a great decrease in hunting pressure (J. Schweizer, personal communication). This includes, but is not limited
to, the Paraguai River itself, the SBo Lourenco, Itiquira and Piquiri tributaries in the northern
Pantanal; and the Negro and Aquidauana Rivers in the southern region (Schweizer, 1986, 1992;
personal communication). They are not found on the extremely polluted Taquari River
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Biology of the Giant Otter 9
(J. Schweizer, personal communication). Dalponte & Cintra ( 1 986) also reported Giant Otters in the
northern Pantanal from the area between the cities o f Poconk and Port0 Jofre and they are present on
the Ivenheima River (J. Schweizer, personal communication). Coimbra-Filho (1 972) states that the
Giant Otter is practically extinct in the entire eastern region of the country, with only very rare
sightings on tributaries of the Parana. They may inhabit the Paranapanema River within the Morro
do Diabo Forest Reserve (Coimbra-Filho, 1972) and the Rio Doce State Park (C. Blacher, personal
communication; Melquist, 1984) and they are reportedly present in the Corrego do Veado and
Sooretama Federal Biological Reserves (IUCN, 1982) and Campos do Jordiio State Park
(CONSEMA, 1985). Since 1991 a resident pair has also been observed on both the Branco and the
das Minas Rivers in the Atlantic Forest (P. Martuscelli, personal communication).
Ecuador, Peru and Bolivia (Figs 6 and 7)
Giant Otters are found only in isolated locations in Ecuador. Melquist ( 1984) reports sightings of
Giant Otters on the Giieppi, a tributary of the Putumayo. They are also reported from several tributaries of the Nap0 River: the Aguanco, including its Tarapoa and Cuyabeno tributaries, the Garza
A
Cuvabeno Wildlife Reserve
Nabonal Park
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Fig. 6. Distribution of Giant Otters in Ecuador and Peru, showing rivers and areas inhabited by Giant
Otters as cited in text. Circles indicate the approximate centre of protected areas.
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Fig. 7. Distribution of Giant Otters in Bolivia, showing rivers and areas inhabited by Giant Otters as
cited in text. Circles indicate the approximate centre of protected areas.
Cocha of the Cuyabeno (within the Cuyabeno Wildlife Reserve) and the Lagarto Cocha; the
Pucuno; the M a n g o Cocha (within Yasuni National Park); and the Pana Yacu (Melendres, 1978;
Melquist, 1984). In the Pastaza River basin, they inhabit the Bobonaza, Oso Yacu and Ishpingo
(Melendres, 1978; Melquist, 1984). In the Tigre River basin, they are recorded only h r n the
Shiona, a tributary of the Conambo (Melendres, 1978).
In Peru, Giant Otters are absent from much of their former range and remnant populations are
confined to undisturbed secluded tributaries of the Amazon (Chehebar. 1990). Brack-Egg ( 1978)
reports Giant Otters in the Pacaya-Samiria National Reserve in north-eastem Peru. In south-eastem
Peru, Giant Otters are present in several areas of the Madre de Dios Basin: an estimated 65-100
Giant Otters inhabit the Manu River (within Manu National Park) (Brecht-Mum & Munn, 1988;
Schenck & Staib, 1992; Staib & Schenck, 1994), -25 otters inhabit the Tambopata River and its La
Torre tributary and low numbers are also present in the Madre de Dios itself and its Blanco, Los
Amigos and Heath tributaries (Schenck & Staib, 1992; Staib & Schenck, 1994).
In Bolivia, current distribution is apparently restricted to the vicinity of the Manuripi Heath
National Wildlife Reserve in the Madre de Dios River basin of northern Bolivia, the Mamore River
and Amboro National Park in the central region, although they are apparently only very rare visitors
to the latter area (Dunstone & Strachan, 1988). Recently 65 Giant Otters have been identified in the
Noel KempffNational Park on the Guapore River (McFarren, 1994); ~ 3 0 are
0 believed to inhabit
the park and surrounding area (D. Quinn, personal communication).
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Paraguay, Uruguay and Argentina (Fig. 8)
The limited distribution information for Paraguay indicates that in the early 1980s Giant Otters
were present on the Verde and Ypane tributaries of the Paraguai River and were occasionally
sighted on tributaries of the Parana River in eastern Paraguay (Melquist, 1984). Remnant
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Biologv of the Giant Otter
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Fig. 8. Distribution of Giant Otters in Paraguay, Uruguay and Argentina. Circles indicate cities or the
approximate centre of protected areas. Dashed lines indicate boundaries of the departments of Salto and
Rocha.
populations may also exist in marshes adjacent to the Paraguai and Pilcomayo Rivers in the south,
but this is unconfirmed (Melquist, 1984).
In Uruguay, the last confirmed register of the species was from Sauce Creek of the Negro River
in 1963 (G. Bardier, personal communication). Sightings were made in 1972 on the Uruguay River
north of Salto, a single individual was seen on Itapebi Creek in this area in 1975 (Melquist, 1984)
and there were two unconfirmed sightings from Salto state in the 1980s (G. Bardier, personal communication). There are unconfirmed reports from Salsipuedes Creek of the mid Negro River
(Melquist, 1984). Giant Otters were believed to exist in the streams and marshes of the department
of Rocha in the early 1980s and are apparently present in the Baiiados del Este Biosphere Reserve
(IUCN, 1982; Melquist, 1984).
In Argentina, Giant Otters are probably now extinct (A. Parera, personal communication). Individuals and pairs were seen on the IgUani River and its tributaries within I g u d National Park until
1988, but there are no current indications ofPteronura in the area (Parera & Bosso, 1991). Massoia
et al. (1987) observed andor collected seven Giant Otters in the Urugua-i tributary of the Parani,
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12 S. K. Carter and F.C. W. Rosas
but the lower portion of this river has since been dammed and shows no recent evidence of
Pteronura (Parera, 1992b). Reports from local residents indicate that Giant Otters were present in
low numbers on the Parana River as late as the 1980s, until 1989 in the Laguna Ibera and surrounding marshes and on the upper Miriiiay River and until 1984 in the Curuzu Cuatia Creek and its tributaries in the lower Miriiiay (Parera & Masariche, 1989; Parera, 1992b).
Captive animals
Table 1 lists known institutions where Giant Otters are currently held in captivity. Captive animals
are breeding in Dortmund and Hamburg, Germany and Cuiaba, Brazil.
HABITAT
Giant Otters inhabit many types of rivers, creeks and lakes in the tropical forests, llanos and
wetlands of South America. Slow moving rivers and streams and oxbow lakes are preferred
(Duplaix, 1980; Schenck & Staib, 1992). Some authors report that Giant Otters prefer larger rivers
(Mondolfi, 1970; Donadio, 1978), although they also frequently inhabit smaller forest creeks
(Duplaix, 1980; S.K. Carter & F. C. W. Rosas, personal observation) and occasionally reservoirs of
large dams (Laidler, 1984; Colares, 1988) and agricultural canals (Chehkbar, 1990). A decided
preference is shown for black or clear waters (Mondolfi & Trebbau, 1978; Duplaix, 1980;
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Table 1. Locations where Giant Otters (Pferomrrubrusiliensis) are currently held in captivity. N o recent information
was obtained from Ecuador or Bolivia
Location
GUYANA
Georgetown
VENEZUELA
Zoologico Miguel Romero Antoni,
Barquisimeto
Parque del Este Romulo Betancourt,
Caracas
Zoologico Leslie Pantin, Turmero
PERU
fquitos
M
F
lndet Source
1
0
0
M. Remdass, personal communication, 1994
1
2
0
V. Katz. personal communication, 1994
1
I
0
V. Katz, personal communication, 1994
1
0
0
V. Katz. personal communication, 1994
0
0
1
E. McCallie, personal communication, I994
0
I
I
I
2
1
2
0
2
0
0
0
0
0
0
0
0
personal observation, 1995
F.N. Armond, personal communication, 1994
A.S.L. Penlta, personal communication, 1994
personal observation, 1993
E. Rodrigues, personal communication, 1994
J. Batista, personal communication, 1994
L.C.Camargo, personal communication, 1994
S.M.C. Machado, personal communication,
1994
BRAZIL
Instituto Nacional de Pesquisas da
Amazhnia, Manaus, AM
UHE Balbina, AM
Emilio Goeldi Museum, Belem, PR
Brasilia, DF
Goiania, GO
Cuiaba, MT
Somcaba, SP
Americana SP
0
1
2
0
1
BOLIVIA
santa CmZ
1
1
0
Dunstone & Strachan, 1988
Tierpark Dorhnund
1
Zoo Duisberg
1
1
1
0
0
I. Schappert, personal communication, 1995
M.G. Hartmann, personal communication, 1994
4
0
0
M. Flugger, personal communication, 1995
1
1
0
R.N. Heap, personal communication, 1995
..7
1
GERMANY
Carl Hagenbecks Tierpark,
Hamburg4tellingen
I J N I E D KINGDOM
Chestnut Centre,
Chaoel-en-le-Frith. Derbvshire
0 1991 Mammal Society, Murnmal Review, 21, 1-26
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Biology of the Giant Otter
13
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Schweizer, 1992) which are reasonably transparent ( 1 .M.3m) and support a large diversity of fish
species (Sioli, 1984; Goulding, Carvalho & Ferreira, 1988). Giant Otters living in muddy or white
waters (transparency 0.1-0.5 m) hunt in isolated areas of clearer water (Mondolfi & Trebbau, 1978;
Schweizer, 1992).
Based on the few long-term studies available, home range appears to be 12-32 km of creek (including its side tributaries) or 20 km’ of lake (Duplaix, 1980; Laidler, 1984). Within these large
home ranges which may overlap, smaller territories centred around good feeding locations are defended by each family group. These territories encompass 2-9.6 km of creek or 5 km2 of lake, depending on food availability, otter density and habitat type (Duplaix, 1980; Laidler, 1984;
Schweizer, 1992). In seasonally flooding areas, territories are defended continuously throughout
the dry season; they are apparently abandoned during the flooded season when the otters move into
the flooded forest to exploit the influx of fish (Duplaix, 1980; Schweizer, 1992). In more stable
environments Giant Otters may display cyclic foraging patterns, visiting and defending specific
territories for a 2-3-day period every 2-3 weeks (Fugger, 198 1; Laidler, 1984).
Giant Otters maintain various campsites within these home ranges. Campsites are semicircular
or rectangular areas along the river or lake bank which the otters clear of vegetation and use regularly for scent marking, drying out and resting or sleeping (Duplaix, 1980; Laidler, 1984) (Fig. 9).
Campsites often begin as simple resting areas 2-3 m in diameter and are enlarged during subsequent visits to an average of 8.7 m in length (range 1.3-3 1.O) by 4.4 m in width (range 1 .O-14.7 m)
(Duplaix, 1980; Laidler, 1984; Schweizer, 1992; S. K. Carter & F. C. W. Rosas, personal observation). Each site contains 1-5 communal latrines which are usually peripheral and average 2.2 m2
(Duplaix, 1980; Laidler, 1984; S.K. Carter & F.C.W. Rosas, personal observation). Campsites are
generally clustered around feeding areas within territories, with each family group maintaining one
cluster of three to eight campsites and possibly a few outliers (Laidler, 1984). They are most often
constructed on shaded level ground which has little ground cover and easy access to small forest
Fig. 9. Giant Otter campsite. Xixuah Creek, Brazil (Photo by S.K.Carter)
0 1997 Mammal Society, Mammal Review, 27, 1-26
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14 S. K.
Carter and F. C.
W. Rosas
creeks, swampy areas, or shallower waters of larger rivers (Duplaix, 1980; Laidler, 1984; S. K.
Carter & F. C. W. Rosas, personal observation). High banks which seldom or never flood are preferred over lower areas and low human disturbance is also important in site selection (Duplaix,
1980; Laidler, 1984). In Suriname, approximately half of the sites were perennial (Duplaix, 1980),
while the present authors found that in their study site on the Xixuau Creek of the lower Jauaperi
River in northern AmazBnia, 20 of 22 campsites used during the study period had been used in previous years.
Giant Otters also build dens in the banks of rivers and lakes within their home range. These dens
are used regularly for sleeping in most areas, although they may be used only temporarily during
cub rearing in others (Laidler, 1984). In northern AmazBnia, the authors found that dens consist of
one to seven entrances (generally 0-4.2 m above the current water mark) which are ~ 0 . 4 m
3 wide
(range 0.18-1.10 m) by 0.28 m high (range 0.12-0.90 m). Other studies have found that den entrances average 0.2-0.4 m in diameter, with older dens having the larger entrances (Duplaix, 1980;
Schweizer, 1992). Tunnels 0.3-3.6 m in length lead from each entrance to one or more chambers
-1.2-1.8
m in diameter and 0.4-0.7 m high (Duplaix, 1980). In the Amazon, dens may also have
several smaller air holes ( ~ 0 . 2 m
6 wide by 0.18 m high) higher up on the bank (S. K. Carter &
F. C. W. Rosas, personal observation). Dens are commonly located under root systems or fallen
trees (Mondolfi, 1970; Duplaix, 1980; Schweizer, 1992; S. K. Carter & F. C. W. Rosas, personal
observation). In the authors’ study site on Xixuau Creek, 15% of 46 dens were found to be adjacent
to campsites and 17% of 46 dens were adjacent to latrines. In addition, 96% of 44 dens were located
in areas with at least 50% tree cover and 90% of 3 1 dens used during the study were perennial.
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BEHAVIOUR
Giant Otters generally live in groups of three to nine consisting of a mated pair and one or two litters. Group size varies with region, habitat and season. Occasionally supergroups of 12-20
individuals are observed, which may be a result of grouping around plentifbl food sources or groups
temporarily travelling together (Mondolfi, 1970; Duplaix, 1980; Laidler, 1984).
Individuals not living in family groups are referred to as transients. Transients may be subadults
recently split from their family group or adults which have lost a mate. They lack established territories and are usually shy and difficult to sight. Associations observed between transients and family groups with subadults nearing dispersal age may indicate a preliminary form of mate selection
(Laidler, 1984; Schweizer, 1992).
Giant Otters are exclusively diurnal. Family groups may travel over 17 km daily, alternately
fishing and patrolling their territories (Laidler, 1984). In their natural habitat, these otters spend
approximately half of their time hunting, travelling and patrolling their territories and half resting
and marking ashore (Duplaix, 1980; Schweizer, 1992). In captivity, Salvo Souza & Best (1982)
found that 3 9 4 6 % of daylight is spent active in the water, 12-17% in terrestrial activities, 8% eating and 3 4 3 6 % resting; activity peaked in the early moming and afternoon. Recent observations
by the authors of a captive adult female at the National Institute of Amazon Research showed that
42.9% of daylight hours were spent in aquatic activities, 26.2% in terrestrial activities, 5.5% eating
and 26.3% resting. Aquatic activity peaked in early moming and again mid afternoon and terrestrial
activity remained fairly constant throughout the day at a level nearly twice that observed by Salvo
Souza & Best (1982). Resting peaked at noon, between the scheduled morning and mid-afternoon
feeding periods (Fig. 10). Fishing activity in wild Giant Otters in Guyana peaked in the morning
(Laidler, 1984), while in Peru peaks were observed in both the morning and afternoon (Fugger,
1981). No specific activity peaks were evident in otters of Kaboeri Creek, Suriname @uplaix,
1980).
Giant Otter groups are highly cohesive: group members rest, play, sleep, travel and fish together,
and mated pairs are often observed allogrooming. Group defence is cooperative with the male
Q 1997 Mammal
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Biology of the Giant Otter
15
lW%.
Eating
Active terrestrially
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E
e
-I-
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12
6
7
8
9
10 l l
13 14 15 16 17
0
7
8
0
10 1 1 12 15 14 15 16 17
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lax41
.-e
?
!
8
L
n
50%m
Resting
mb
6
7
8
0
10 1 1
Active aquatically
12 13 14 15 16 17
6
Daylight hours
7
6
0
10 1 1
12 13 14 15 18 17
Daylight hours
Fig. 10 Summary of principle diurnal activities of a Giant Otter (Pteronura brasiliensis) at the National
Institute of Amazon Research, Manaus, Brazil. A total of 1554 observations were made at 10 minute
intervals during 60 days in the period of January 1993-February 1994. Number of observations per hour
ranges from 68 to 158.
generally taking the front line, while females may determine other group movements and activities
(Trebbau, 1972; Duplaix, 1980; Laidler, 1984; Brecht-Munn & MUM,1988; Schweizer, 1992).
Hunting appears to be cooperative only in circumstances where the prey species is too large to be
subdued by a single otter (e.g. large Anacondas Eunectes murinus and Black Caimans
Melanosuchus nigec Brecht-Munn & MUM, 1988). Supposed cooperation observed in other cases
(Hershkovitz, 1969) may be an incidental result of group members fishing individually but in close
proximity. Food sharing is common among captive Giant Otters, but it has only been observed in
two field studies (Brecht-Munn & Munn, 1988; Schweizer, 1992). To date no aggression within
Giant Otter family groups has been observed and at least one case of altruistic behaviour involving
a pair and their cubs has been documented (Schweizer, 1992).
Giant Otters appear actively to avoid direct agonistic encounters with other groups. Intergroup
communication and temtory defence is mainly indirect through the construction and scent marking
of campsites; vocal communication may play a smaller role in territorial demarcation (Duplaix,
1980; Schweizer, 1992). In areas of high otter density, range expansion often involves temtorial
fights (Schweizer, 1992).
Giant Otters vocalize frequently using variations and combinations of the nine basic calls described by Duplaix (1980) and Laidler ( 1984). The HAH! and snort express alarm or warning to the
group and the growl is a low-pitched threat. The di- or trisyllabic contact call is given frequently
when travelling and fishing. Adults convey aggression, defence, or high excitement in the caterwaul or wavering scream, while cubs caterwaul to beg for food or express frustration. The hum is a
reassurance close-contact sound which may be interspersed with COOS when used by mated pairs or
parents and their cubs. Newborns squeak during their first few days to communicate fear, hunger,
8 1997 Mammal Society, Mammal Review, 21, 1-26
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16 S. K. Curter and F. C. kV. Rosas
location and/or general discomfort; they later develop a whine to beg for food and express general
defensive annoyance or pain.
DIET
Direct observation and faecal analysis in various regions have revealed that fish constitute the majority of the Giant Otter’s diet. They generally fish in the shallow margins of lakes and rivers
(Duplaix, 1980; Defler, 1983; Brecht-Munn & Munn, 1988; Schweizer, 1992) where fish density is
high (Lowe-McConnell, 1975). Giant Otters may catch up to 3.2 fisWotter in shallow water
(< 0.60 m), while hunting in deeper water (3-10 m) is much less rewarding (1.8 fisWotter)
(Laidler, 1984). Wild adults consume an estimated 3 kg of fish daily (Duplaix, 1980; Schweizer,
1992).
Most fish consumed by Giant Otters belong to the suborders Characoidei (characins), Percoidei
(perch) and Siluroidei (catfish). Species are consumed in varying amounts according to their relative abundance and vulnerability to Giant Otter predation. Slow moving and nocturnal fish are easy
prey for Giant Otters, along with those which often rest immobile on lake or river bottoms in wait
of prey (Duplaix, 1980; Laidler, 1984; Schweizer, 1992). The preferred size range is 0.10-0.40 m
in length depending on the species (Duplaix, 1980; Fugger, 1981). The upper limit appears to be
0.60 m in most circumstances (Duplaix, 1980; Fugger, 1981), although some authors have observed Giant Otters eating enormous catfish (probably Pseudopfaqstornafasciaturn which easily
attain lengths of over 1 m) in the Amazon and Orinoco basins (Mondolfi, 1970; Santos, 1984).
Characoids appear to be the most widely consumed prey of Giant Otters. In Guyana, 73.5% of
spraints contained remains of the cliaracoid Hoplias rnalubaricus (Erythrinidae) and approximately
half of the catches observed in Suriname were of this species (Duplaix, 1980; Laidler, 1984). In
north central AmazBnia, F. C. W. Rosas, J. A. S. Zuanon & S. K. Carter (unpublished data) found
characoids in 86.5% of samples; Best ( 1 984) found the characoid Schizodor~sp. (Anostomidae) was
the most commonly consumed species, with Hoplius spp. taken less frequently. Other frequently
eaten characoids are members of the families Serrasalmidae, Characidae and Curimatidae (Duplaix,
1980; Laidler, 1984; Benetton, Rosas & Colares, 1990).
Siluroids and percoids also make up a substantial portion of the Giant Otter diet. Cichlids (suborder Percoidei) were consumed more frequently (present in 96.8% of spraint samples) and in
greater bulk than any other prey in Guyana (Laidler, 1984) and were present in 97.3?/0 of samples
from north central AmazBnia (F. C. W. Rosas et al., unpublished data), although they were less
important in other regions (Duplaix. 1980; Fugger, 1981). Plagioscion auraturn (Sciaenidae) made
up about one third of the diet in a Peruvian study (Fugger, 1981). Siluroid remains were present in
at least 34% of faeces samples from Guyana and one area of north central AmazBnia (Laidler, 1984;
Benetton et al., 1990), however, only 5.4% of faeces sampled from Xixuau Creek contained
siluroid remains (F. C. W. Rosas et al., unpublished data). Siluroids constituted 22% of the catches
observed by Duplaix (1980) in Suriname.
In only one study did an invertebrate species occur in a significant portion of spraints: Duplaix
( 1980) found crab remains in 40% of analysed samples. Most of these samples were single spraints
(rather than communal latrines) which appeared to be deposited outside the core areas of home
ranges, tentatively suggesting that crab may have been a prey item consumed on seasonal visits to
outer limits of the home range. In all other studies, mammal, amphibian, reptile, bird, crustacean
and mollusc remains were rare (generally < 2%) in faeces samples (Laidler, 1984: Benetton et al.,
1990; F. C. W. Rosas ef al., unpublished data). Other vertebrates consumed in various locations
include Anacondas under 3 m, other snakes under 2 m, Black Caimans under 1.5 m and turtles
(Podocnemis unlfilis and Hydromedusa tectifera) (Laidler, 1984; Brecht-Mum & Munn, 1988;
Schenck & Staib, 1992; Martuscelli, in press).
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D 1997 Mammal
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Biology of the Giant Otter
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In captivity, Giant Otters are generally fed a variety of fish supplemented with vitamins and
sometimes vegetable oil. They have also been given other meats (poultry, beef, horse and donkey
meat) and bread soaked in milk and egg (Zeller, 1960; Trebbau. 1972). In the Brasilia zoo, Giant
Otters frequently catch herons which gather in their enclosure to feed on leftover fish (C. L.
MagalhPes, personal communication). The present authors found that a captive adult consumed
10.0% (range 6.0-16.0%) of its body weight daily and a subadult consumed 13.4% (range
8.0-1 8.9%). These results are similar to studies by Zeller (1960) and Best (1985) which reported
daily food consumption by adults and subadults is 7.0-9.6% and 12.9% of their body weight, respectively. Schweizer (1992) reported a higher consumption rate of 25% of the total body weight
for one subadult.
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PREDATION AND COMPETITION
Adult Giant Otters living in family groups have no known important natural predators, but there are
some records of Black Caimans in Peru and Spectacled Caimans Cuimun yucure in the Pantanal
preying on Giant Otters (Brecht-Munn & Munn, 1988; Schweizer, 1992). Solitary animals and
unattended cubs may be vulnerable to attacks from various mammals and reptiles including Anacondas and Jaguars Pantheru onca, which are known to prey on Lutru sp. (Duplaix, 1980; Laidler,
1984). White-lipped Peccaries Tuyasszr pecari have also been suggested as predators of cubs
(Schenck & Staib, 1992).
The Neotropical Otter Lurru longicuudis, sympatric in much of Pteronrrm's range, is the Giant
Otters' most significant competitor, but several factors appear to minimize direct competition. First,
the Giant Otter usually frequents larger rivers and their oxbow lakes, while the Neotropical Otter
inhabits smaller creeks, lakes and swampy areas further from the main rivers (Duplaix, 1980;
Schweizer, 1992). Second, the latter species apparently does not need dens on 'terra firma' (land
above the seasonal flood mark) to raise its young (Schweizer, 1992) and Neotropical Otters often
use natural openings in rocky areas as shelter, which are not used by the Giant Otter (Blacher, 1987;
Olimpio, 1992). Third, the Neotropical Otter preys on smaller fish than the Giant Otter as well as
having a much wider diet which, besides fish. includes crustaceans (especially freshwater shrimp),
small mammals, amphibians, reptiles and birds (Blacher, 1987; Olimpio, 1992; Parera, 1992a;
Schweizer, 1992). Finally. the Neotropical Otter is nocturnal or crepuscular in some areas unlike
the strictly diurnal Giant Otter (Duplaix. 1980; Blacher, 1992).
Other animals which consume only or mainly fish in habitats fully or partially overlapping that
ofthe Giant Otter include some caimans (Melanosuchusniger, Cuimun yucare and C. crocodylus),
large piscivorous siluroids, characoids and gyrnnotoids (Duplaix, 1980; Laidler, 1984; Schweizer,
1992) and the river dolphins (Sotufiaj7rrviatifisand Inia geoffrensis) which inhabit the Amazon and
Orinoco Basins. We suggest that competition by both dolphin species is minimal because of spatial
separation and dietary preferences. Sotulia generally frequents large open bodies of water and consumes mainly diurnal pelagic fish (da Silva, 1983), which would appear to minimize both habitat
and dietary overlap with the Giant Otter. Iniu may exploit the shallow water of the flooded forest
during the rainy season (Best & da Silva, 1989) and its diet is more varied with a less pronounced
preference for diurnal pelagic fish (da Silva, 1983). This could indicate higher habitat and dietary
overlap with the Giant Otter. However, both dolphin species consume mainly small fish (< 20 cm)
which are on the low end of the size range preferred by Giant Otters. Defler (1983) observed associations between Pteronzrra and Iniu and suggested that the dolphins may benefit by fish fleeing
from the Giant Otters.
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0 1997 Mammal Society, Mammal Review, 21, 1-26
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18 S. K. Carter and F. C. W. Rosas
REPRODUCTION AND CUB DEVELOPMENT
Information on the reproductive characteristicsof Giant Otters is scanty and primarily derived from
captive observations of a few animals. Giant Otters are estimated to be sexually mature at 2 years
(Laidler & Laidler, 1983). The 21-day oestrous cycle continues year round (Laidler, 1984) and
numerous authors have found females to be receptive from 3 to 10 days during this cycle. Zeller
(1 960) differed, finding the heat period to be 14 days during January and April. Nipples and vulva
swell during the receptive period and females may be more aggressive and display less desire for
food and play (Zeller, 1960; Laidler, 1984),although Trebbau (1978) observed no change in behaviour. Copulation takes place in the water and has been described by Autuori & Deutsch (1977) and
Trebbau (1978). Breeding is apparently possible year round and peak birthing occurs during the
dry season in environments with marked flooded and dry seasons (Duplaix, 1980; Brecht-Munn &
MUM, 1988; Schweizer, 1992). Records of captive births show no peak.
One to five (average two) cubs are born following a 52-70-day gestation period (Autuori &
Deutsch, 1977; Trebbau, 1978; Brecht-Munn & MUM, 1988; Schweizer, 1992). Survival rate in
captivity is less than 30%: common causes of mortality are accidents, parents eating their young,
gastroenteritis and epileptic attackdconvulsions (Trebbau, 1972; Trebbau, 1978; Autuori &
Deutsch, 1977; Salvo Souza & Best, 1982; Lima & Lima, 1984). In captivity, the interlitter period
may be as little as 77 days when all cubs of the previous litter are lost. If at least one cub survives,
captive interlitter period is w 9 months, while intervals of 2 1 and 33 months were observed in the
field (Laidler, 1984).
At birth, Giant Otters weigh -0.20 kg and measure 0.33 m (Autuori & Deutsch, 1977). Cubs are
cared for by both parents and siblings; older siblings may leave the group temporarily when the new
cubs are born, returning 6 4 weeks later (Dupiaix, 1980; Brecht-Munn & Munn, 1988; Schenck &
Staib, 1992). Cubs are kept within the family den for 2-3 weeks before being introduced to the
water by their parents. At one month their eyes open and they are able to swim (Autuori & Deutsch,
1977). By 6 weeks cubs regularly follow their parents out of the den and play around the den’s
entrance with supervision fiom parents or subadult siblings, but they do not begin hunting and travelling with the family until they are 3-4 months old (Duplaix, 1980; Laidler, 1984; Brecht-Munn &
MUM, 1988). Cubs are weaned by 9 months and after 10 months they hunt as successfully as their
parents and can no longer be distinguished from adults in the wild (Laidler, 1984; Brecht-Munn &
Munn, 1988). Juveniles begin marking on their parents’ campsites at about 1 year of age and remain
with the family group for approximately 2 years (Laidler, 1984; Schweizer, 1992).
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PHYSIOLOGY
Few physiological studies of Giant Otters exist. Marsicano et 41. (1986) described anaesthesiology
of a captive adult with ketamine hydrochloride, finding effective dosages of 10.0-10.6 m a g , depending on the animal’s condition. Colares & Best (1991) described haematological and chemical
blood parameters which are similar to those of the Sea Otter, and Rosas & Lehti (1992) found Zn,
Na, Cu, Mg, Mn, Fe and Ca levels in fur to be comparablewith those of other carnivores. Digestive
efficiency is -75% and passage time through the digestivetract in captivity ranges from 35 min to
about 2 h (Duplaix, 1980; Best, 1985). Field observations by Schweizer (1992) indicate a passage
timeof-1
h
Laidler (1984) observed low heat tolerance in captive otters, which may be a result of the elevated metabolic rates of mustelids in general (Iversen, 1972)combined with the high ambient temperatures found throughout most of the Giant Otter’s range.
8 1997 Mammal Society, Mammal Review, 27, 1-26
Biology of the Giant Otter
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STATUS
Since 1978 the Otter Specialist Group of the World Conservation Union (IUCN) has considered
Pteronura brasiliensis the most endangered otter species in the world. The species, however, is
classified as ‘vulnerable’ by IUCN (1990). It has also been listed on Appendix I (species threatened
with extinction) of the Convention on International Trade in Endangered Species of Wild Fauna
and Flora (CITES). This convention, enacted in 1973 and now ratified by all South American countries, authorizes international trade only in exceptional circumstances. However, CITES does not
regulate domestic trade nor enforce habitat protection. Giant Otters are also protected by national
laws within all South American countries (with the possible exception of French Guiana), but trade
bans did not come into effect in some countries until the mid 1970s and enforcement is nearly
impossible.
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PAST AND PRESENT THREATS
Before large-scale settlement of the Amazon Basin began in the early 1960s, pelt hunters were the
main threat to Giant Otter populations. Remaining populations of Giant Otters now face severe
pressure from increasing colonization and exploitation of natural resources such as hydroelectric
power, minerals and fossil fuels which contaminate or destroy formerly pristine tropical forests and
water systems.
Hunting
Giant Otters can be easily located because of their noisy diurnal habits and conspicuous campsites.
These characteristics, combined with the high value of their pelts ($US 27-90 or more) (Doughty &
Myers, 1971; Donadio, 1978; Ayres & Best, 1979), led to extensive uncontrolled hunting in the
1950s and 1960s. Official statistics indicate that over 40 663 pelts were exported from Brazil alone
from 1960 to 1967 (Best, 1984). This is probably a gross underestimation of the actual number of
Giant Otters killed because (i) 60% of animals sink before they can be recovered by hunters
(Coimbra-Filho, 1972); (ii) any dependent cubs are effectively killed with the death of a parent; and
(iii) the sale of many skins never appears on official records because of smuggling or under-invoicing by exporters (Donadio, 1978). Trade is now banned and pelt prices have dropped significantly
($US10-20), but Giant Otters continue to be hunted for their pelts (Duarte & RebZlo, 1985; Emory,
1990; Schenck & Staib, 1992; Bisbal, 1993). Before the implementation of CITES, the USA and
Europe (particularly West Germany and the UK) were the main importers of Giant Otter pelts
(Doughty & Myers, 1971). In 1981, West Germany imported 1007 pelts from Italy, with Paraguay
the reported country of origin (Fitzgerald, 1989), and in 1982,547 pelts were confiscated in Brazil
(Duarte & RebZlo, 1985). Small numbers of Giant Otters are also hunted for meat by Amerindians
in Colombia and Guyana (Laidler & Laidler, 1983; Defler, 1986), captured for the zoo trade
(Schweizer, 1992) and robbed by locals from their dens as cubs to be sold or kept as pets (Duplaix,
1980; S. K. Carter & F. C. W. Rosas, personal observation). However, the current effect on the
overall population from direct capture or killing of animals is minor compared with the increasing
threat to existing populations from habitat loss and degradation.
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Colonization and deforestation
The increasing development and subsequent human invasion of vast tracts of tropical forest is rapidly making many areas incapable of supporting Giant Otter populations. Colonization of the
Amazon Basin has historically been limited to the areas along navigable waterways, but recently
many roads have been built by logging and mining companies and for government projects. This
opens up large areas to invasion by hunters and settlers and consequently more people must depend
on the river for food, as fish is their principal source of animal protein (Santos, Ferreira & Zuanon,
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S. K . Curter und F. C. W. Rosas
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1991). This leads to conflict with resident otters, which are highly visible, often feared and consume
large quantities of fish. Also, the nutrient-poor soil in the Amazon Basin will support agricultural
crops and cattle pasture for only 3 4 and 10 years, respectively. which leads to further clearing and
burning of the forest. Feamside (1993) estimated that as of 1990, 10.5% of the Brazilian Amazon
had been deforested.
Hydroelectric dams
Hydroelectric dams have been constructed on rivers throughout the Amazon, Orinoco and La Plata
basins. The majority of rivers selected for damming are black or clear water (Junk & Nunes de
Mello, 1987), the favoured habitat of the Giant Otter. Thus the fate of aquatic fauna in these reservoirs and their future suitability as Giant Otter habitat is of key importance.
Dams have flooded a current total of 5429 km?in the Brazilian Amazon and this may soon be
increased to 11 060 km2by another eight dams in the final stages of planning (Nunes de Mello,
1993). Dams make formerly inaccessible areas accessible, leading to the indiscriminate exploitation of natural resources in the area and potential invasion by hunters (Junk & Nunes de Mello,
1987). They also profoundly affect fish populations by interrupting migratory routes and drastically
changing hydrological and water-quality conditions (Junk, 1983; Petts, 1990; Leite & Bittencourt,
1991). Preliminary studies show that there is a temporary boom in the number of predatory fish,
particularly Serrusalrnus spp., after filling (Leite & Bittencourt, 199I), but populations of many
migratory species are greatly reduced or disappear in and above the reservoir (Ferreira, 1984; Junk
& Nunes de Mello, 1987). Three years after damming the Tocantins River at Tucurui (Brazil), the
fish population remained unstable and biomass and species diversity were significantly decreased
(Leite & Bittencourt, 1991). In Suriname, the Brokopondo reservoir was still relatively poor in
aquatic fauna and flora after 20 years (Junk & Nunes de Mello, 1987).
Mining
Gold mining is common in areas of the Orinoco and upper Paraguai River basins, on the Saramacca
and Marowijne Rivers in Suriname and on rivers throughout the Amazon Basin including the Madre de Dios, Madeira, Negro, Branco and Tapajos, all of which are or were inhabited by Giant
Otters. Gold is mined from these rivers by dredging. This produces large amounts of suspended
particulate matter in the water, which interferes with light penetration, buries bottom-dwelling algae species and asphyxiates fish (Alho, Lacher & Gonqalves, 1988). Once sludge is removed,
mercury is used to separate and amalgamate the gold particles. Approximately I . 3 4 0 kg of mercury are released into the surrounding environment for each 1.O kg of gold produced (Mallas &
Benedicto, 1986; Pfeiffer & de Lacerda, 1988) and as much as 4 5 4 0 % of this mercury flows directly into the water (Pfeiffer & de Lacerda, 1988). Recent research by Forsberg et al. (in press) has
shown that mercury contamination is especially critical in black-water rivers, which promote naturally high mercury concentrations because of their low pH and conductivity and high content of
dissolved organic material.
Once in the aquatic ecosystem, metallic mercury may be changed to its more dangerous organic
form (methylmercury) and transferred through the food chain, magnifying at successive trophic
levels (biomagnification). Predatory fish accumulate significantly higher tissue mercury concentrations than herbivorous and omnivorous species from the same area of the Amazon (Martinelli et af.,
1988; Forsberg et af. in press; C. R. Padovani, B. R. Forsberg & T. P. Pimentel, unpublished data)
and Kucera (1983) found that North American River Otters accumulate 10 times more mercury than
predatory fish. Bioaccumulation has been demonstrated in otters as well: Kruuk & Conroy, (1991)
and Mason & Madsen ( 1 992) found higher mercury levels in adult otters than in juveniles and
subadults.
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Biologp of the Girrnt Otter 2 I
Mercury accumulates in the hair, liver, kidney. muscle and brain tissues of otters, causing progressive central nervous system deterioration and death in laboratory tests (O'Conner & Nielsen,
1980; Kucera, 1983; Wren, 1986). O'Conner & Nielsen ( 1980) predicted that mercury poisoning
would occur in wild otter populations in watersheds where fish regularly contain 2 parts per million
(wet weight) methylmercury. Sublethal effects on reproduction, growth and behaviour may occur at
lower concentrations (Wren, Stokes & Fischer, 1986). As predatory fish in some areas of the Amazon have mercury tissue concentrations of up to 2.63 p.p.m. (Forsberg er al. in press) and there is no
sign of a decrease in gold mining, it is possible that Giant Otter populations could be affected by
mercury poisoning in the future. Mercury poisoning in humans has been confirmed in several areas
of the Amazon Basin (Homcwood, 199I).
The most dangerous consequence of mining of other mineral resources such as bauxite, iron ore
and coal in the Amazon may be the accompanying development which results in large areas of forest being disturbed, cleared or settled. This is particularly evident in the Serra dos Carajas where
development projects related to the exploitation of iron ore and other minerals are expected to destroy almost all of the forest east of the Tocantins River by the end of the century (Johns, 1988).
Fossil fuels
Oil is currently exploited in the Orinoco and far western Amazon basins and recently large deposits
of oil and natural gas have been discovered in the Urucu and Jurua River basins in the western
Amazon of Brazil (Johns, 1988). The road building invohed in oil exploration often leads to invasion ofthese areas by settlers, as happened in the Cuyabeno Wildlife Reserve and will likely happen
in Yasuni National Park, both legally protected areas in Ecuador inhabited by Giant Otters (Collins,
1990). During drilling and recovery. there IS the risk of a spill or blow-out along with further contamination of water systems from oil, effluents and drilling mud (a mixture of clay, water,
chemicals and sometimes oil) (IUCN, 1991). Contamination is extensive in Ecuador where ruptures
in one main pipeline have spilled over 16 million gallons of oil into the water system in the last 20
years. Ten thousand gallons are spilled weekly from secondary lines. Further damage is caused by
the more than 4.3 million gallons of untreated toxic waste the petroleum industry dumps into the
watershed daily (Kane, 1994).
Industrial pollution
Industrial pollution in the more developed Paraguai, Orinoco and La Plata basins has also affected
aquatic fauna. Alcohol distilleries in the Pantanal produce large amounts of stillage. a by-product of
the sugar cane distillation process. The distilleries' widespread discharge of stillage into water
courses causes eutrophication and deoxygenation of water, alters its temperature and pH and has
been linked to numerous fish kills (Alho et al., 1988). In the Orinoco, the heavy use of pesticides in
the Portuguesa and Cojedes subbasins has caused fish mortality (Colonnello, 1990), and the new
industrial development project in the basin includes plans for a wood pulp processing plant and a
large crude oil refinery which would likely increase pollution in other areas. Changes have also
been observed in fish species of the lower La Plata basin, a system polluted with agricultural and
industrial toxic substances and altered by various hydroelectric dams (Quiros, 1990).
RECOMMENDATIONS
As with other Neotropical species, protection of quantity and quality of habitat is required to ensure
the survival of the Giant Otter. This may best be carried out through the development of long-term
sustainable development projects combined with the establishment and fiscalization of adequately
located and sized protected areas. In addition, we recommend elevating the status of the Giant Otter
in the IUCN Red Data Book from 'vulnerable' to 'endangered' and hrther studies on the effects of
natural resource harvest and extraction.
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22 S. K. Carter and F. C. W. Rosas
Reevaluation of Red List status
We believe that the status of the Giant Otter should be changed from ‘vulnerable’ to ‘endangered’
according to the new criteria for the Red List Categories in Version 2.2 of IUCN (1994). The species has been decimated in the southern portion of its original distribution. Pelt export statistics
indicate that Giant Otters were heavily exploited in much of the remainder of their historical range
through at least the 1960s. The remaining scattered populations in South America face immediate
and increasing threats to the quantity and quality of their habitat. Based on this information, the
species has experienced a severe decline over the last five generations in extent of occurrence, area
of occupancy and quality of habitat and thus should be considered ‘endangered’ under criterion A1
of endangered species of IUCN (1994).
Habitat protection
Long-term studies by independent researchers on the ecological effects of hydroelectric dams, mining and oil exploration are needed. Of particular importance to Giant Otter conservation are studies
on the effects of large dams on the diversity and abundance of fish populations and the extent to
which animals at the top of the aquatic food chain are affected by biomagnification and
bioaccumulation of mercury in the ecosystem.
ACKNOWLEDGEMENTS
We thank P. Martuscelli, H. Reichart and the many researchers of the National Institute of Amazon
Research (INPA) and members of the IUCN Otter Specialist Group who provided information on
the current distribution of the Giant Otter. We also thank the many people who kindly provided
information on captive animals. The Associaqao AmazBnica and N. Gordon of Survival Films provided logistical support in the field.
We are grateful to E. McCallie, E.S.Carter, K.K.Lehti and S. R. Seavey for valuable comments
made on earlier drafts of this manuscript.
S. K. Carter was supported by a graduate scholarship from the United States Fulbright Commission; MPA provided infrastructure and technical support.
REFERENCES
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Alho, C.J.R., Lacher, T.E. Jr & Gonqalves, & H.C. (1988) Environmental degradation in the Pantanal ecosystem.
BioScience, 38 (3). 164-1 7 1.
Almeida, R.T., Pimentel, G.P. & Pimentel. D.S. (1991) Aspectos biogeogrificos dos marniferos aquaticos do estado
do Maranhk, Brasil. Abstractr of the t’Reunidn de Trabajo de Especialistas en Mamiferos Acuaticos de
America del Sur. Buenos Aires, Argentina. 28 September-2 October, 1992, p. 3.
Autuori, M.P. & Deutsch, L.A. (1977) Contribution to the knowledge of the giant Brazilian otter, Pteronura
brasiliensb (Gmelin 1788), Carnivora, Mustelidae. Der Zoologische Garten, 47( I), 1-8.
Ayres, J.M. & Best, R. (1979) Estrategias para a conservaclo da fauna amaz6nica. Acta Amazonica (Suplementu),
9(4), 81-101.
Ballard, K.A., Sivak, J.G. & Howland, H.C. (1989) lntraocular muscles of the Canadian nver otter and Canadian
beaver and their optical tinction. Canadian Jounral of Zoology, 67(2), 469-474.
Benetton, M.L.F.N., Rosas, F.C.W. & Colares, E.P. (1990) Aspectos do habito alimcntar da ariranha (Pteronura
brasiliensis) na Amaz6nia Brasileira. Abstracts of the IV Reunion de Trabajo de Esperialistas en Mamiferos
Acuuricos de America del Sur. Valdivia, Chile, 12-15 November, 1990, p. 6.
Best, R.C. (1984) The aquatic mammals and reptiles of the Amazon. In: The Amazon. Lirnnology and Landscape
Ecology of a Mighty Tropical River and its Basin (ed. by H. Sioli), pp. 371412. Dr W. Junk Publishers,
Dordrecht.
Best, R.C. (1985) Otters and manatees conservation. Conclusions of the I Reunion de Trahujo de Expertos en
Mamifeos Acuaticos de America del Sur. Buenos Aires, Argentina. 25-29 June, 1984, pp. 64-75.
Best, R.C. & da Silva, V.M.F. (1989) Biology, status and conservation of Inia geoflrensis in the Amazon and
Orinoco River basins. In: Biology and Conservation of the River Dolphins (ed. by W.F. Perrin, R.L. Brownell Jr,
2.Kaiya & L. Jiankang), pp. 23-34, Occasional Papers of the IUCN Species Survival Commission (SSC), No. 3,
IUCN.
zyxwvuts
zyxwvutsrqpo
0 1997 Mammal Society, Mammal Review, 27, 1-26
zyxwv
zyxw
zyx
zyxwvutsrqp
zyxwvutsr
Biology ofthe Giant Otter 23
Bisbal, F.J. ( 1993) Impacto humano sobre 10s carnivoros de Venezuela. Studies on ,Veotropical Farina and Environment, 28 (3), 145-156.
Bjork, P.R. (1970) The Carnivora of the Hagerman local fauna (late Pliocene) of southwestern Idaho. Transactions
of the American Philosophical S0cier.v. 60 (7). 1-54.
Blacher, C. (1987) Ocorrencia e presewaqio de Lutra longicaudis (Mammalia: Mustelidae) no litoral de Santa
Catarina. Boletim Fundaqiio Brasileira para a Conservaqa'o da Natureza. 22, 105-1 17.
Blacher, C. (1992) A Lontra: Aspectos de sun Biologia. Ecologia. e Conservaqa'o. Instituto Brasileiro do Meio
Ambiente e Recunos Naturais Renovaveis (IBAMA). Universidade Federal de Santa Catarina, Florianopolis,
sc.
zyxwvutsr
zyxw
zyxwvu
Brack-Egg, A. (1978) Situaci6n actual de las nutrias (Lutrinae, Mustelidae) en el Peru. In: Proceedings of the First
Working Meeting of the Otter Specialist Group (ed. by N. Duplaix), pp. 76-84. Paramaribo, Suriname, 27-29
March, 1977.
Brecht-Munn, M. & Munn, C.A. (1988) The Amazon's gregarious giant otters. Animal Kingdom, 91(5), 34-41.
Cabren, A. & Yepes, J. (1940) Historia Natural Ediar. Mamiferos Sud-Americanos (Vida. Costumbres y
Descripcion). Compafiia Argentina de Editores, Buenos Aires.
Chanin, P. (1985) The Natural Histoy of Otters. Croom Helm Academic Press, London.
Chehebar, C. (1990) Action plan for Latin American otters. In: Otters: an Action Plan for Their Conservation (ed.
by P. Foster-Turley, S. Macdonald & C. Mason), pp. 64-73. IUCN/SSC Otter Specialist Group. Chicago Zoological Society, Brookfield.
Coimbra-Filho, A.F. (1972) Mamiferos ameagados de extinqio no Brasil. In: Especies da Fauna Brasileira
Ameacada de Extincdo, pp.75-78. Academia Brasileira de Ciencias, Rio de Janeiro.
Colares, E.P. (1988) Lontras-da bacia do Rio UatumH-AM. Abstracts of the III Reunion de Trabajo de Especialistas
en Mamgeros Acuaticos de America del Srir. Montevideo, Uruguay, 25-30 June, 1988, p. 29,
Colares, E.P. (1990) Pteronura brasliensis na llha de Maraca, Roraima, Brasil. Abstracts of the IY Reunion de
Trabajo de Especialistas en Mamgeros Acuaticos de America del Siir. Valdivia. Chile, 12-1 5 November, 1990,
p. 18. Centro de Investigacions y Manejo de Mamiferos Marinos. Valdiva, Chile.
Colares, E.P. & Best, R.C. (1991) Blood parameters of Amazon otters (Lutra longicaudis, Pteronura brasiliensis)
(Carnivora, Mustelidae). Comparative Biochemistty and Physiology. Part A. Comparative Physiology, 99A (4),
5 13-5 15.
Collins, M. (ed.) (1990) The Last Rain Forests: a World Conservation Atlas. Mitchell Beazley in association with
IUCN (The World Conservation Union), London.
Colonnello, G. ( 1 990) Elementos fisiogrificos y ecologicos de la cuenca del rio Orinoco y sus rebalses. Interciencia,
15 (a), 476-485.
Conselho Estadual do Meio Ambiente (CONSEMA). (1985) Areas Naturais do Estado de 550 Paulo. CONSEMA,
SHo Paulo, 16, pp.
Dalponte, J.C. & Cintra, R. (1986) Ocorrtncia de espkies de Mamiferos no Pantanal Matogrossense. Abstracts of
the XIII Congress0 Brasileiro de Zoologiu. Cuiabi, Brasil, 2-7 February, 1986, p. 231. Fundagio Universidae
Federal de Mato Grosso and Sociedade Brasileira de Zoologia, Cuiaba, Brasil.
Davis, J.A. (1978) A classification of the otters. In: Proceedings of the First Working Meeting of the Otter Specialist
Group (ed. by N. Duplaix). pp. 14-33. Paramaribo, Suriname, 27-29 March 1977. International Union for the
Conservation of Nature, Morges, Switzerland.
Defler, T.R. (1983) Associations of the giant river otter (Pteronura brasiliensis) with fresh-water dolphins (Inia
geoflrensis). Journal of Mammology, W 4 ) . 692.
Defler, T.R. (1986) The giant river otter in El Tuparro National Park. Columbia. 0ry.x. 20 (2), 87-88.
Donadio, A. ( I 978) Some comments on otter trade and legislation in Colombia. In: Proceedings of the First Working
Meeting of the Otter Specialist Group (ed. by N. Duplaix) pp. 34-42. Paramaribo, Suriname, 27-29 March,
1977.
Doughty, R.W. & Myers, N. (1971) Notes on the Amazon wildlife trade. Biological Conservation, 3(4), 293-297.
Duarte, J.C.S. & Rebelo, G.H.(1985) Carnivore skins held in Brazil. Traflc Bulletin, 7 (I), 1 6 1 7 .
Dunstone, N. & Suachan, R. (1988) Status and distribution of otters in the Amboro National Park, Bolivia. IUCN
Otter Specialist Group Bulletin, 3, 24-33.
Duplaix, N. (1980) Observations on the ecology and behaviour of the giant river otter Pteronura brasiliensis in
Suriname. Revue Ecologique (Terre Vie), 34,495-620.
Eisenberg, J.F. (1989) Mammals of the Neofropics, Vol. 1 f i e Northern iveotropics: Panama. Colombia, Venezuela,
Guyana, Suriname, French Guiana. University of Chicago Press, Chicago & London.
Emory, J. (1990) Brazil's Pantanal, 'That land of wonderful inundation': a naturalist reveals a water-drawn wilderness in the heart of South America. Nature Conservancy 40 (September-October), 6-15.
Feamside, P.M. (1993) Deforestation in Brazilian Amazonia: the effect ofpopulation and land tenure. Ambio, 22 (S),
537-545.
Ferreira, E.J.G. (1984) A ictiofauna da represa hidreletrica de Curua-ha, Santakm, Para. 1- Lista e distribuiqHo das
especies. Amazoniana, 8 (3), 351-363.
zyxwv
0 1997 Mammal Society, Mammal Review, 27, 1-26
zyxwvutsr
zyxwvutsrqp
zyxwvutsrq
zyxwvutsrq
zyxwvutsrq
zyxwvutsrqp
24 S. K. Carter and F. C. W. Rosas
zyxwvu
zyxwv
zyxwvuts
Fitzgerald, S. ( 1989) International Wildl!feTrade: Whose Business Is It? World Wildlife Fund, Washington, DC.
Forsberg, B.R., Forsberg, M.C.S., Padovani, C.R., Sargentini, E. & Malm, 0. (in press) High level of mercury in fish
and human hair from the Rio Negro basin (Brazilian Amazon): Natural background or anthropogenic contamination? In: Environmental Pollution b j .Mercur? Due to Gold Mining (ed. by W.C. Pfeiffer). Minamata Research
Institute, Japan.
Foster-Turley, P., Macdonald, S. & Mason, C. (eds) (1990) Otters: on Action Plan for Their Conservafion. IUCN/
SSC Otter Specialist Group. Chicago Zoological Society, Brookfield.
Fountain, P. (1902) The Great Mountains and Forests of Sourh America. Lon-pans, Green & Co., London.
Fugger, B. (1981) Some first observations on the ecology and ethology of a group of giant river otters (fteronura
brasiliensis, Gmelin, 1788) in the Manu National Park, Peru, unpublished report cited by Laidler, P.E. (1984).
The behovioural ecology of the giant otter in Gii.vana. PhD thesis, University of Cambridge, 296 pp.
George, T.K., Marques, S.A., de Vivo. M.,Branch, L.C., Gomes, N. & Rodrigues. R. (1988) Levantamento de
Mamiferos do Pama-Tabajos. Brasil Florestal O(Jan/Fev/Mar), 3 3 4 1 .
Goulding, M., Carvalho., M.L. & Ferreira, E.G. (1988) Rio Negro, Rich L$e in Poor N'urer. SPB Academic Publishing, The Hague.
Handley. C.O. Jr ( 1976) Mammals of the Smithsonian Venezuelan Project. Brigham Young University Science Bulletin. Biological Series, 20(5), 1-89,
Hams, C.J. (1968) dtters: a Studv of the Recent Lutrinae. Weidenfeld & Nicolson, London.
Hershkovitz, P. (1969) The evolution of mammals on southern continents. VI. The recent mammals of tho
Neotropical region: a zoogeographic and ecological review. Qirarterlv Review of Biology. 44 (I). 1-70.
Homewood, B. (1991) Mercury poisoning confirmed among Amazon villagers. New Scientist, 132 (1794), 18.
Husson, A.M. (1978) The MammaIs ofSuriname. E.J. Brill, Leiden.
International Species Information System (ISIS). (1993) Mammal Abstract. ISIS, Apple Valley.
IUCN. ( 1982) IUCN Directory of Neotropical Protected Areas. Tycooly International Publishing Ltd, Dublin.
IUCN. ( I 990) 1990 IUCN Red List of Threatened Animals. IUCN. Gland & Cambridge.
IUCN. (1991) Oil &.rploratioii in the Tropics: Guidelines for Environmental Protection. IUCN, Gland & Cambridge.
IUCN. (1992) Otters. IUCN, Species Survival Commission, Gland.
IUCN. (1994) Species. Newsletter of the Species Survival Commission. 1UC.V. 21-22. 134 pp.
Ivenen, J.A. (1972) Basal energy metabolism of mustelids. Journal of Cornpararive Pliysiology, 81, 341-344.
Johns, A.D. (1988) Economic development and wildlife conservation in Brazilian Amazonia. Ambio, 17 (5).
302-306.
Junk, W.J. (1983) As aguas da regiio Anaz6nica. In: Amuzdnia: Desenvolvimenro, IiitegracZo e Ecologia (ed. by E.
Salati. W. Junk, H. 0. R. Shubart & A.E. Oliveira), pp. 45-100. Editora Brasiliense and Conselho Nacional de
Desenvolvimento Cientifico e Tecnologico (CNPq), S5o Paulo.
Junk, W.J. & Nunes ds Mello, J.A.S. (1987) lmpactos ecologicos das represas hidrelitricas na bacia AmazBnica
Brasileira. Tiibinger Geographische Studien. 95, 367-385.
Kane. J. (1994) Moi goes to Washington. The Xew Yorker 2 May 1994, 74-81,
Kucera, E. (1983) Mink and otter as indicators of mercury in Manitoba waters. Canadian Journal ot'Zoologv, 61,
2250-2256.
Kruuk, H. & Conroy, J.W.H. (1991) hlonalit? of otters (Lutra lutro) in Shetland. Journal of Applied Ecology, 28,
83-94.
Laidler, P.E. (1984) The behaviourul ecologr. ofthe giant otter iii Guyana. PhD thesis, University of Cambridge,
296 pp.
Laidler, K. & Laidler, L. (1983) The River Wo!lo!t:George Allen & Unwin, London.
Leite, R.A.N. & Bittencourt. M.M. ( 1 991 1 Impacto das hidroeleuicas sobre a ictiofauna da Amazhia: o exemplo de
Tucurui. In: Bases Cienrifcas paru Estrategias de freservaqa'o e Desanrolvimento cia Amazdnio: Fatos e
ferspcctivas (ed. by A.L. Val, R. Figliuolo Sr E. Feldberg), pp. 85-100. Vol. 1. lnstituto Nacional de Pesquisas
da AmazBnia, Manaus.
Lima, R.D.M. & Lima, L.P. ( 1 984) Notas sobre a reproducio de ariranha, Preronura brasiliensis (Gmelin, 1788) no
zoo de Brasilia, 4 pp. (unpublished).
Lowe-McConnell, R.H. ( I 975) Fish Conimunities in Tropical Freshwaters. Longman, London & New York.
McFarren, P. (1994) Ecological tourism goal of Bolivia. The Oregonian 19 September 1994, p. A5.
Mallas, J. & Benedicto, N. (1986) Mercury and gold mining in the Bwilian Amazon. Ambio, 15. 248-249.
Marsicano, G., Rosas, M.M., Rosas, F.C.W. & Souza, R.H.S. (1986) ContenGao de lontraq amazanicas coin
Cloridrato de Ketamina. A Hora Yeterincirio, 6(31), 5-8.
Martinelli, L.A., Ferreira. J.R., Forsberg, B.R. & Victoria, R.L. (1988) Mercury contamination in the Amazon: a
gold rush consequence. Ambio. 17, 252-254.
Martuscelli. P. (in press) Hydrontedusa tectijeru (South American snake-necked turtle). Naniral enemies.
Herpetological Review.
0 1997 Mammal Sociery, Mammal Review. 27, 1-26
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Mason, C. (1990) An introduction to the otters. In: 0tter.Fr an Action flanfor Their Conservation (ed. by P. FosterTurley, S. Macdonald & C. Mason). pp. 4-7. IUCN/SSC Otter Specialist Group. Chicago Zoological Society,
Brookfield.
Mason, C.F. & Macdonald, S.M. (1956) Otters: Ecologv and Consenation. Cambridge University Press, Cambridge.
Mason, C.F. & Madsen. A.B. (1992) Mercury in Danish otters (Lutra liitra). Chemosphere, 25 (6). 865-867.
Massoia, E., Vaccaro, O.B.. Galliari. C. 8~ Ambrosini, S. (1987) La mastofauna del Rio Urugua-i, provincia de
Misiones. Revista del Muse0 Argentino de Cihcias Naturales 'Bernardino Rivadavia '. Zoologia, 14(8),
I 1 1-124.
Melendres, A.P. ( 1978) Notas sobre las nutrias de no del Ecuador. In: Proceedings of the First Working Meeting of
the Otter Specialist Groiip (ed. by N. Duplaix), pp. 56-66. Paramaribo, Suriname, 27-29 March, 1977. International Union for the Conservation of Nature, Morges, Switzerland.
Melquist, W.E. (1984) Starus sum? o/otters lLiitrinae) and spotted cats (Felidae) in Latin America. Completion
Report, Contract no. 9006, IUCX. College of Forestry, Wildlife, and Range Sciences, University of Idaho,
269 pp.
Mondolfi, E. (1970) Fauna de Venezuela amenazada de extincion: las nutrias 0s perros de agua. Defensa Naturaleza,
1 ( I ) , 24-26, 47.
Mondolfi, E. & TRbbau, P. ( 1978)Distribution and statusof the giant otter (Pteronurabrasiliensb) in Venezuela In: froceedings of the First Workurg Meeting oj.the Otter $wcialist Group (ed by N. Duplaix), pp. 44-54. Paramaribo, Suriname,
27-29 March 1977. International Union for the C m a t i o n of Nature, M o m , Switzerland
Murphy, C.J., Bellhorn, R.W., Williams. T., Bums, M.S., Schaeffel, F. & Howland, H.C. (1990) Refractive state,
ocular anatomy, and accommodati\e range of the sea otter (Enhydra lutris). Vision Research, 30 ( I ) , 23-32.
Nunes de Mello, J.A.S. (1993) Hidreletricas na Amazdnia e o meio ambiente. In: Bases Cientificaspara Estratigias
de Preservaqcio e Desenvolvimeitto da Ama-inia (ed. by E. J. G.Ferreira, G. M. Santos, E. L. M LeHo & L. A.
Oliveira), pp. 11-16. Vol. 2. Instituto Nacional de Pesquisas da Amazdnia, Manaus.
O'Conner, D.J. & Nielsen, S.W. (1980) Environmental survey of methylmercury levels in wild mink (Mustela vison)
and otter (Lritra canadensis) from the northeastern United States and experimental pathology of
methylmercurialism in the otter. In: Worldwid- Furbearer Conference Proceedings (ed. by J.A. Chapman & D.
Pursley), pp. 1728-1745. Vol. Ill. Frostburg, Maryland, 3-1 1 August. 1980.
Olimpio, J. ( 1992) Consideraqcks preliminares sobre habitos alimentares de Lutra longicaudis (Olfers, 1818)
(Carnivora: Mustelidae), na Lagoa do Pen, llha de Santa Catarina. In: Proceedings of the III Reunidn de Trabajo
de Especialistas en Mamifros Aciiaticos de America del Sur (ed. by J.A. Oporto, L.M. Brieva & R. Praderi), p.
9. Montevideo, Uruguay, 25-30 July, 1988.
Parera, A. (1992a) Analisis de la dieta de Lutra longicaudis en laguna Iberi, provincia de Comentes, Argentina.
Abstracts of the V Reunion de Especialistas en Mami/eros Acuaticos de America del Sur. Buenos Aires. Argentina, 28 September-2 October, 1992, p. 49.
Parera, A.F. (1992b) Present knowledge on the gia,it otter in Argentina. ICJCN Otter Specialist Group Bulletin, 7,
19-22.
Parera, A. & Bosso, A. (1991) Mustelidos acuaticos del no 1Superior. Proyecto Arirai. Fundacion para la
Conservacion de las Especies y el Medio Ambiente (FUCEMA), 35. pp. (unpublished).
Parera, A. & Masariche, M. (1989) Informe de la primera carnpafia del Proyeto Arirai. Fundacion Vida Silvestre Argentina, 34 pp. (unpublished).
Petts, G.E. (1990) Regulation of larse rivers: problems and possibilities for environmentally sound river development in South America. Interciencia, 15 (6). 388-395.
Pfeiffer, W.C. & de Lacerda, L.D. (1988) Mercury inputs into the Amazon region, Brazil. Environmental Technology Letters, 9, 325-330.
Quiros, R. (1990) The Parana river basin development and the changes in the lower basin fisheries. Interciencia, 15
(6). 442-451.
Radinsky, L.B. (1968) Evolution of somatic sensory specialization in otter brains. Journal of Comparative Neurology, 134, 495-506.
Rios, U.G. (1987) Proyecto para evaluacion de las poblaciones de nutria o perro de agua (fteronura brasiliensis) en
10s llanos de Portuguesa. (unpublished).
Robertson, J.S. Jr (1976) Latest Pliocene mammals from Haile XV A, Alachua County, Florida. Bulletin of the
Florida State Museum. Biologiccll Sciences, 20(3), 1 11-186.
Rosas, F.C.W., Colares, E.P., Colares., I.G. & da Silva, V.M.F. (1991) Mamiferos aquaticos da AmazBnia Brasileira.
In: Bases Cientifcas para Estrategias de Preservaccio e Desenvolvimento do A m a - A a : Fatos e Perspectivas
(ed. by A.L. Val, R. Figliuolo & E. Feldberg), pp. 405-41 1 . Vol. 1. Instituto Nacional de Pesquisas da
Amazdnia, Manaus.
R o w , F.C.W. & Lehti, K.K. (1992) Conteudo mineral do pel0 da ariranha (fteronura brasiliensis). Abstracts of the
V Reunidn de Trabajo de Especialistas en Mamifeos Acuaticos de Amirica del Sur. Buenos Aires, Argentina. 28
September-2 October, 1992, p. 59.
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0 1997 Mammal Society, Mammal Review, 21, 1-26
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26 S. K . Curter and F. C. W. Rosas
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Salvo Souza, R.H. (1982) Diario da segunda excunio ao alto Curua-Una a procura de ariranhas, 16 pp. (unpublished).
Salvo Souza, R.H. & Best, R.C. (1982) Contribuiqio sobre o comportamento da ariranha (Pterontrra brasiliensis
Gmelin 1788) em cativeiro. Contribuiqio no. 34 da DivisZo de Mamiferos Aquaticos. lnstituto Nacional de
Pesquisas da Amazhia, Manaus, 3 1 pp. (unpublished).
Santos, E. (1984) Entre o Gamba e o Macaco: Vida e Costumes dos Mamijeros do Brasil. Editora Itatiaia Ltda, Belo
Horizonte. (This title originally published in 1945 by F. Briguiet & Cia.. Rio de Janeiro.)
Santos, G.M., Ferreira, E.J.G. & Zuanon, J.A.S. (1991) Ecologia de peixes da AmazBnia. In: Bases Cientijcaspara
EstratPgias de PreservaCdo e Desenvolvimento da Amaz6nia: Fatos 8 Perspectivas (ed. by A.L. Val, R.
Figliuolo & E. Feldberg). pp. 263-280, Vol. I. Instituto Nacional de Pesquisas da AmazBnia, Manaus.
Schenck, C. & Staib, E. (1992) Status. Behaviour and Protection of Giant-Otters in Pent. Final Report, 25 pp. (unpublished).
Schweizer, J. (1986) Oco&ncia de ariranhas (Pteronura brasiliensis, Gmellin, 1788) (Mustelidae) no Pantanal de
MS. Abstracts of the XIII Congress0 Brasileiro de Zoologia. Cuiaba, Brasil, 2-7 February, 1986, p. 228.
FundaqPo Universidae Federal de Mato G r o w and Sociedade Brasileira de Zoologia, Cuiabi, Brasil.
Schweizer, J. ( 1992) Ariranhas no Pantanal: Ecologia e Comportamento da Pteronura brasiliensis. Edibran-Editora
Brasil Natuma Ltda, Curitiba.
da Silva, V.M.F. (1983) Ecologia alimentor dos golfinhos do Amazdnia. MSc thesis, FundaqPo Univenidade do
Amazonas (FUA)/lnstituto Nacional de Pesquisas da AmazBnia (MPA), 112 pp.
Sioli, H. (1984) The Amazon and its main affluents: hydrography, morphology of the river courses, and river types.
In: The Amazon. Limnologv and Landscape Ecology of a MighF Tropical River and its Basin (ed.by H. Sioli),
pp.127-165. Dr W. Junk Publishers, Dordrecht.
Staib, E. & Schenck, C. (1994) Giant Otter. A Giant Under Even Bigger Pressure. SchencVStaib, Frankhn. 36, pp.
Thornback, J. & Jenkins, M.(1982) The IUCWMammal Red Data Book. Part I : Threatened Mammalian Taxa of the
Americas and the Australasian Zoogeographic Region (Excluding Cetacea). IUCN, Gland.
Trebbau, P. (1972) Notes on the Brasilian giant otter (Pteronura brasiliensis) in captivity. Der Zoologische Garten
41 (3/4), 152-156.
Trebbau, P. (1978) Some observations on the mating bshaviour of the Brazilian giant Otter (Pteronura brasihensis).
Der Zoologische Garten 48 (213). 187-188.
Van Zyll de Jong, C.G. (1972) A systematic review of the Nearctic and Neotropical river otter (Genus Lutra,
Mustelidae, Carnivora). Lye sciences Conrributions. Royal Ontario Museum, 80, 1-104.
Walls, G.L. (1963) The Vertebrate Eye and its Adaptive Radiation. H a h e r Publishing Company, New York & London.
Wren, C.D. (1986) A review of metal accumulation and toxicity in wild mammals. I. Mercury. Environmental Research, 40, 2 10-244.
Wren, C.D., Stokes, P.M. & Fischer, K.L. (1986) Mercury levels in Ontario mink and otter relative to food levels and
environmental acidification. Canadian Journal of Zoology, 64,2854-2859,
Zeller, F. (1960) Notes on the giant otter (Pteronura brasiliensis Zimm) at Cologne Zoo. lnrernativnal ZOOYearbook, 2, 8 1.
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