Reproduction, behaviour and biology of the Giant river otter

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360 THE DEVELOPING ZOO WORLD

Int. Zoo Yb. (2006) 40: 360–371 © The Zoological Society of London

Reproduction, behaviour and biology of the Giant river
otter
Pteronura brasiliensis
at Cali Zoo
G. CORREDOR LONDOÑO1 & N. TIGREROS MUÑOZ2
1
Head, Research Centre for Conservation of Endangered species (CREA) at Cali
Zoological Foundation and 2Research Associate, CREA, Carrera 2a Oeste Calle 14
esquina, Zoológico de Cali, Cali, Colombia
E-mail: gcorredor@zoologicodecali.com.co

The Giant river otter Pteronura brasiliensis is only occurred in Brazil, Germany and
endemic to South America and is Endangered.
Breeding in captivity is one of the strategies for con-
Colombia at six institutions (Sykes-Gatz,
servation of the species, despite the fact that histori- 2001). Acoustic and visual protection
cally this has not been successful. Between 1999 and from human disturbance during the
2004 a study into the behaviour and reproductive breeding period has been the most signifi-
biology of a pair of Giant river otters was carried cant animal-management factor contrib-
out at Cali Zoo. The 8 gave birth to nine litters, with
14.6.1 pups born, 6.4 (48%) of which survived to uting to successful parent rearing of Giant
q1 year old. Two litters were reared with older sib- river otters in zoos (Sykes-Gatz 1998/
lings in the family group. Evidence of delayed 2002, 2001, 2004). Stress resulting from
implantation and pseudopregnancy were observed. human disturbance, inadequate manage-
The roles of the 8, 7 and juveniles in pup rearing
are described. Significant features of infant develop-
ment and/or environment, and disease
ment were recorded and a growth curve was estab- have all caused reproductive failure
lished for P. brasiliensis up to 2 months old. (Duplaix-Hall, 1975; Hagenbeck & Wün-
nemann, 1992; Wünnemann, 1995).
Key-words: behaviour, captive breeding, giant river Little is known about the reproductive
otter, husbandry, management, reproduction
biology and ecology of P. brasiliensis
(Staib & Schenck, 1994; Carter & Rosas,
The Giant river otter Pteronura brasi- 1997), and much less about its behaviour.
liensis is one of the major carnivores of This study focuses not only on the repro-
South America and one of the most duction of the species in captivity but also
threatened mammals in the world (Wün- on aspects of its biology and reproductive
nemann, 1995). Given that the species is behaviour.
Endangered (IUCN, 2004), specific prior-
ities have been defined for its conserva- METHODOLOGY
tion. These include in situ and ex situ Cali Zoo has maintained Giant river
strategies, such as undertaking field sur- otters since 1993 and a stable pair formed
veys, protected-area management, legal in 1998. The reproductive activity of this
protection, public education and captive- pair was studied for 5 years consecutively
breeding programmes (Foster-Turley (1999–2004). Management techniques
et al., 1990). were evaluated and the biology and
In 2003 the world population of Giant behaviour of the species were observed.
river otter in captivity was 60 individuals
at 26 institutions (Sykes-Gatz & Gatz, Observations Reproductive behaviour
2004). Successful captive-breeding has during the first 4 months post partum was

CALI ZOO: GIANT RIVER OTTER REPRODUCTION AND BEHAVIOUR 361

studied for the litters born in July 2002 Enclosure The enclosure had a total area
and February 2003 (Table 1). General of 300 m2, with a water:land ratio of 2:1.
observations were made at The walls were constructed of 2 m-high
0700–1200 hours and 1300–1700 hours, artificial rock, with plants on top of the
4 days per week. The pups were observed walls. Three nestboxes were provided: one
using an infrared camera in the nestbox was made of brick and cement with a
and direct observations of the enclosure wood substrate, another was made of
area. In August 2003 pups from litter 7 wood and a third of artificial rock with a
were observed in order to expand and soil and sand substrate. The artificial-rock
confirm the observations from previous nestbox was located in the quietest area of
litters. the enclosure, remote from the manage-
The effects of rearing neonates with sib- ment area, other exhibits and the public,
lings from previous litters were evaluated and this nestbox was used most often
in February–June 2003 when litter 6 was during breeding periods. The entrance to
born. The three (1.2) 7 month-old juve- this nestbox was a 2·5 m-long tunnel, cre-
niles from litter 5 remained with the ated from dead tree trunks and artificial
family group throughout the rearing rock, ending in a 1·7 m1·2 m0·7 m-
process. high chamber with a soil and sand sub-
Data about the behaviour of the par- strate. The pool was 25 m6 m with a
ents and three juveniles were collected depth that ranged from 1·2 m at the
every minute for observation sessions of deepest point to 0·30 m at the shallow
5 hours per day (between end.
0800–1200 hours and 1300–1600 hours),
4 days a week in February–June 2003. Management Approximately 1 week
Thus, an observation session was a before expected parturition, the public-
300 minute-long period. The behaviours viewing window was visually isolated by
of juveniles are presented as averages of erecting a 2 m-high sheet of green poly-
the behaviours recorded individually for propylene. Observations were carried out
each animal. Although the data presented through four 13 cm2 cm observation
some variation in the time spent on each points cut into the polypropylene. After
activity there was not a significant differ- parturition, particularly during the first
ence between the behaviours recorded for 2 weeks, every effort was made to keep the
the three individuals. area as quiet as possible both near the

litter date no. successful
no. pups litter

1 2 Nov 1999 1.1.1 no
2 31 Jan 2001 1.0 no
3 20 Apr 2001 2.0 yes
4 13 Nov 2001 2.1 no
5 14 Jul 2002 1.2 yes
6 12 Feb 2003 2.1 yes*
7 12 Aug 2003 1.0 yes
8 7 Feb 2004 2.0 no
9 22 Apr 2004 2.1 yes

* One 8 survived and two 77 died.
Table 1. Litters of Giant river otters Pteronura brasiliensis born at Cali Zoo
between November 1999 and February 2004.

362 THE DEVELOPING ZOO WORLD

Plate 1. Family group of Giant river otter Pteronura brasiliensis at Cali Zoo. Pierre Gay, Zoo de Doué, Doué
la Fontaine. France.

nestbox and around the enclosure. In the drained and then treated with Cefazolina
first 3 months after the 8 had given birth (antibiotic injection) for 4 days. While the
keepers did not enter the exhibit. Food pups were treated the adults were occu-
was provided in a small room that was far pied with live fish in the pool. The med-
away from the nestbox, pool water was ical-intervention procedures, and
changed at night and the latrine was weighing, measuring and taking the
cleaned by the frequent addition of sand. temperature of each pup, did not last
In 2001 the exhibit was closed to the more than 10 minutes. If the nestbox was
public for 4 months while the pups were found to be too wet (likely caused by the
reared successfully. In 2002 the exhibit adults entering the nestbox still wet from
was closed for 3 months and in 2003 for the pool) sand was added.
2·5 months for each litter. The exhibit was The Giant river otters were routinely
reopened to the public gradually over a offered dead Trachinotus spp fish and,
period of 15 days. During this time public occasionally, live Tilapia spp fish for
viewing was restricted to about ten people environmental-enrichment purposes. [The
at any one time, viewing the Giant river feeding of live vertebrates is not legal in
otters through the open observation many countries.] Food was offered four
points in the polypropylene screen. The times per day. Each adult consumed a
isolation measures used at Cali Zoo fol- mean 2 kg daily (1·7–2·5 kg) and 1 year-
lowed procedures recommended in the old juveniles c. 2·5–3 kg.
literature (Autuori & Deutsch, 1977; Hag-
enbeck & Wünnemann, 1992; Wünne- REPRODUCTIVE BIOLOGY
mann, 1995; Flügger, 1997; Sykes-Gatz, Breeding occurred throughout the year
2001). (Table 1) and between November 1999
Pups occasionally required medical and April 2004 the 8 gave birth to nine
treatment so they were handled periodi- litters, five (56%) of which survived, at
cally. In February 2003 an 8 day-old 8 least partially. A total of 14.6.1 pups was
with a bacterial infection was successfully born and 6.4 survived to q1 year old
treated with Amikin (antibiotic injection) (48%) (Plate 1).
for 6 days. In August 2003 a 17 day-old 7 For 3–10 days after parturition,
had a subcutaneous oedema that was whether or not the pups survived, the

CALI ZOO: GIANT RIVER OTTER REPRODUCTION AND BEHAVIOUR 363

no. pups in litter time between time till delayed
before the delayed two litters implantation*
implantation (days) (days)

1 180 97
1 180 98
2 208 126
3 216 131
Correlation r0·96, PQ0·05 r0·95, PQ0·05

* (Time from last post-partum copulation to next litter)(gestation
period).
Table 2. Correlation between number of pups in the litter before the delayed
implantation, and the time between litters and delayed implantation.

adults were observed copulating neonates died soon after birth, the next
repeatedly for 8·622·5 days (range litter was born after a period of 77 days
5–11 days, n7). Mounting lasted or more. Because copulations were only
5–110 minutes. The 7 always initiated observed post partum, the implication is
copulation. The dorso–ventral position that P. brasiliensis can retain a zygote for
was used for copulation: the 7 placed his delayed implantation whether or not pups
head and anterior body on top of the 8, survive. It would appear that the retained
twisting the posterior body (usually the zygote is implanted either after the pups
left side) to use a ventro–ventral die or once the litter is 3·7–4·9 months
approach. At the onset of oestrus, the 7 old. The duration of the zygotic retention
attempted to copulate with the 8 on land is directly correlated with the number of
or in the nestbox but successful intromis- pups from the previous parturition
sion always occurred in shallow water (r0·95, PQ0·05, n4) (Table 2). There
where the 8 could support her forefeet. may be a correlation between the number
Copulation was easier to observe when of pups the 8 is rearing and the time to
the Giant river otters were isolated from next parturition. The action of nursing
public view because mating occurred in pups may create hormonal changes in the
the early morning or late afternoon when 8 that affect the time of zygotic retention.
visitors were around. A more intense period of feeding, of the
The mean gestation period was sort that occurs when there are several
7022·1 days (n3). Four pseudopreg- pups, appears to delay implantation of the
nancies were observed, during which the zygote (H. Bateman, pers. comm.).
8’s abdomen expanded and the mammary The mean number of pups per litter was
glands developed but parturition did not 2·3320·87 (n9) and the sex ratio was
occur. On one occasion palpation con- 2:1 (7:8) (Table 1).
firmed that the uterus was empty. The Since the litter of 22 April 2004 the 8
duration of a pseudopregnancy was has not become pregnant again. At that
similar to the gestation period (72 days). time she was 11 years old, and her oes-
This phenomenon has also been recorded trous and mating periods were becoming
in the Asian small-clawed otter Aonyx infrequent. After the post-partum mating
cinerea (Bateman, 2003). in 2004, she mated three times in 2005
The mean interbirth interval between (February, May and August) but no
litters was 180–214 days (n4) and the 8 mating has been observed in 2006. The 8
gave birth to a new litter when the older had a false pregnancy in October 2005.
pups were 6–7 months old. However, if All these characteristics may be indicative

364 THE DEVELOPING ZOO WORLD

% time spent on activity

8 7 juveniles

Resting 53 33 38

Time in water 18 42 38

Playing 7 12 30

Table 3. Activity budgets of a social group of Giant river otters while a new
litter was being reared. Percentages are calculated from the observations of
1.1 adults and 1.2 juveniles in February–June 2003.

of the end of this 8’s reproductive cycle branch, or seeds) or a sibling. Play activity
(Sykes-Gatz, 2004). took up almost 30% of the time of juve-
niles during observation sessions but the
values were much lower for the 7 (12%)
REPRODUCTIVE BEHAVIOUR and 8 (7%). The 8 spent more time in the
Activity budgets When the 8 was nearing nestbox than the 7 and juveniles during
parturition, she spent more time in the the rearing period. In the first 2 months
nestbox and her movements became the 8 was observed to spend 56–71% of
slower. At the same time, all the Giant her time in the nestbox with the pups,
river otters were quieter, only vocalizing nursing and/or sleeping (Table 4).
when stressed (e.g. by strangers or noise). In 2002, 15 weeks after parturition, the
Parturition occurred at 0800–1000 hours Giant river otters left the artificial-rock
(n4 litters). nestbox permanently and moved into the
The 8 was less active than the rest of wooden nestbox. It is assumed that the
the group while she was rearing pups. For artificial-rock nestbox became too wet
4 months, she rested 53% of the time because the soil and sand substrate did
during observations, compared to 33% the not drain properly. The pups born in Feb-
7 and 38% for juveniles (Table 3). When ruary and August 2003 were moved sev-
they were not resting the Giant river otters eral times to different nestboxes but the
were often observed in the water. The 8 original nestbox was not abandoned per-
remained in the water for only 18% of manently, perhaps because new sand was
time during observation sessions, com- added to the nestbox every c. 2 weeks.
pared to 38% for the juveniles and 42%
for the 7. Playing included turning over
in the water, chasing each other and biting Development of pups When the pups
either an object (e.g. a piece of wood or were 1 month old, principally the 8 but

% time spent in den/month

1 2 3 4

8 71 56 40 23
7 23 19 19 11
Juveniles 33 40 37 19

Table 4. Time (%) the family group spent in the den during the first 4 months
post partum in 2002 and 2003.

CALI ZOO: GIANT RIVER OTTER REPRODUCTION AND BEHAVIOUR 365

also the 7 and juveniles began to take the the pups began to suckle they emitted an
pups out the nestbox regularly. In the intermittent sound and moved their tails
beginning the 8 transported the pups in (Sykes-Gatz, 2003). The pups also vocal-
her mouth (Duplaix-Hall, 1975) but after ized and moved their tails when the 8
day 65 the pups walked out the den fol- cleaned their faeces away by eating them
lowing the adults/juveniles. From then on, (Fig. 2).
the pups spent more time outside the During the daily observation period in
nestbox (Fig. 1). Sometimes young the first month the 8 spent 40% of her
(q30 days old) pups were carried to the
time nursing the pups, which gradually
pool and put into the water (four times in
2002 and ten times in 2003). This behav- decreased to 32% in the second month,
iour generally coincided with stress, such 26% in the third month and 19% in the
as an unusual noise or the presence of a fourth month. The 8 fed the pups four to
stranger. five times per 5 hour-long observation ses-
Once the pups were c. 1 month old the sion in the first month, about three times
8 began taking them into the pool regu- in the second and third month, and one
larly to teach them to swim. Initially, she or two times in the fourth month (Fig. 3).
would swim with a pup held in her mouth. Although it was not possible to determine
Soon, however, she would let it go and the exact age of weaning as it varied for
swim with the pup against her chest, each litter, it appears to be at
pushing it to the surface as necessary with 16–18 weeks.
her snout and forefeet. At 65 days old the The pups began to eat fish at
pups were able to swim independently. 10–12 weeks of age. The 7 and 8 both
offered soft pieces of fish to the pups
Feeding the pups The 8 directed the pups 1–2 weeks before they began to eat solid
towards her teats using her forefeet. When food. Although initially the juveniles took

Fig. 1. Time (%) that Giant river otter Pteronura brasiliensis pups spent out of the nestbox during the first
4 months of life at Cali Zoo: [n3 pups from litter 5 (2002) and n1 pup from litter 6 (2003)].

366 THE DEVELOPING ZOO WORLD

Fig. 2. Giant river otter pups move their tails laterally when suckling and when the 8 is cleaning away faeces.

the fish away from the pups, after a few a few seconds. From the outset the juve-
weeks they offered food (Fig. 4). niles played with both the 7 and pups,
and contributed to the supply of solid
food offered to their younger siblings.
Roles in rearing During the first
4 months the 8 remained with the pups
most of the time. Nursing and cleaning
faeces were exclusively 8 tasks. The 8 also NEONATE DEVELOPMENT
taught the pups to swim.
Based on the observations of three
The 7 had little contact with the pups
breeding events (litter 3, litter 5 and
during the first 2 months, particularly
litter 6), significant features of infant
when pups were reared with older siblings.
development were recorded for the first
However, the 7 protected the family by
patrolling the territory while they slept. 4 months (Table 5). The neonates open
He was more alert (head raised, periscope their eyes in week 4 and begin to walk in
position) and vocalized with greater fre- week 5, although they are more co-ordi-
quency than the rest of the group (Fig. 5). nated by week 6. By week 9 the pups will
The 7 offered food to the pups from follow the adults out the nestbox.
c. 10 weeks and played with the juveniles Although the mother will take them in the
and pups q3 months old. pool from week 5 and they can swim
In August 2003 a pup was reared suc- alone at c. 8 weeks of age, it is not until
cessfully with two 8 siblings, 13 months the pups are 12–14 weeks old that they
and 6 months old. In general juveniles had swim confidently.
a great deal of contact with pups and, Body-mass measurements were col-
when the adults left the nestbox, even lected for two pups (a 8 from litter 6 and
slept with them. Juveniles were often a 7 from litter 7) in order to develop a
observed handling the pups and placing growth curve for the first 70 days (Fig. 6).
them on their abdomens, imitating the The neonates that did not survive all had
behaviour of the adult 8. On three occa- body-mass measurements that fell below
sions a juvenile was observed nursing for the expected value on the growth curve.

CALI ZOO: GIANT RIVER OTTER REPRODUCTION AND BEHAVIOUR 367

Fig. 3. Time the 8 spent nursing pups and the frequency of feeding during 300 minutes of observations in the first
4 months.

REPRODUCTIVE FAILURE 1996). Although juveniles handled and
The primary cause of death in Giant river played with their younger siblings, they
otter pups in captivity is parental stress, generally did not mistreat them at Cali
culminating in inadequate care, caused by Zoo. This may have been because the par-
human disturbance (Sykes-Gatz, 2001, ents had significant experience of infant
2004). In addition, first litters may not rearing, and stress and disturbance were
receive adequate parental care because the kept to a minimum around the enclosure
parents are inexperienced. It is likely that area. However, the death of a litter in
many Giant river otters in captivity have February 2004 was believed to have been
been separated from their family group at caused by a 6 month-old juvenile that
an early age and may not have previous continually carried the pups.
experience of successful pup rearing after Several neonate deaths in river-otter
the birth of younger siblings. species have been caused by disease
Stress can affect infant rearing in most (Duplaix-Hall, 1975; Hagenbeck & Wün-
mammals in captivity and in Giant river nemann, 1992). Medical treatment can be
otters this may show itself as excessive provided if the pups are monitored regu-
‘carrying behaviour’, which tires the pups larly (e.g. by camera) and if there is safe
and may result in their death (Baker et al., access to the nestbox. Checking the

week development

4 neonates open their eyes
5 pups begin to walk, raising their bodies a little
6 movements are better co-ordinated
9 pups leave the nestbox, walking out the entrance following the adults; about this time pups
also start using the latrine
8 pups swim by themselves, initially with their heads held out of the water
10–12 pups begin to eat fish; use the latrine
12 pups submerge totally for short and intermittent periods in the pool
14 pups observed playing and turning over in the water

Table 5. Summary of observations of the development of Giant river otter pups at Cali Zoo.

368 THE DEVELOPING ZOO WORLD

Fig. 4. Frequency that parents and juveniles offered fish to pups during the first 4 months post partum: top. litter 5
(2002), n3 pups; bottom. litter 6 (2003), n1 pup.

development of the pups and measuring The reproductive biology of this species
body mass may be crucial for the early is highly complex. The pair repeatedly
detection and treatment of some diseases. copulated post partum, at a similar fre-
However, medical treatment should only quency and duration to that recorded in
be carried out if necessary so as not to the literature (Trebbau, 1978; Hagenbeck
cause stress to the adults or pups. & Wünnemann, 1992). As has been
described for the North American river
otter Lutra canadensis and other mustelids
DISCUSSION (Duplaix-Hall, 1975; Foster-Turley et al.,
The breeding activity of this pair of 1990; Lewis, 1995; Partridge, 1997),
P. brasiliensis at Cali Zoo is one of the zygotic retention or delayed implantation,
most successful in the history of main- suggested by Flügger (1997), has been
taining the species in captivity. The iso- confirmed in P. brasiliensis in the study
lation provided and restricted reported here. Pseudopregnancies have
management of the enclosure, plus the been observed in P. brasiliensis, North
compatibility of the pair and their American river otters and Asian small-
breeding experience have been key to this clawed otters (Duplaix-Hall, 1975;
success. Bateman, 2003; Sykes-Gatz, 2003).

CALI ZOO: GIANT RIVER OTTER REPRODUCTION AND BEHAVIOUR 369

Fig. 5. Time (%) spent patrolling the area or giving warning vocalizations in a group of Giant river otters in the
first 4 months post partum in 2003.

During the breeding period, the 8 and handle the pups more gently. The
spends more time resting and less time juveniles observe this behaviour and learn
active in the water than 88 that are not how to handle the pups and offer them
rearing young and the rest of the family solid food during the rearing process.
group (Carter & Rosas, 1997). The 7 Therefore, both parents and juveniles
spends most of his time outside the improved their parental abilities.
nestbox, resting, swimming or patrolling As they have gained greater experience,
the territory. The juveniles spent time with this pair has become more tolerant of cer-
both the 8 and the 7, although some tain disturbances and in 2003 it was
showed a preference for spending time possible to open the exhibit to the public
with one parent or the other. 75 days after parturition and the nestbox
Unlike reports in the literature, rearing could be checked regularly. Strange
new pups with other siblings was generally noises, such as machines or shouting, still
successful at Cali Zoo because the juvenile cause the group to vocalize and, in more
did not tend to hurt the neonates or drink extreme cases, the pups were moved from
the 8’s milk (Wünnemann, 1995; Flügger, the nestbox and put into the pool.
1997). Although the juveniles tried to play Moving pups to different dens is
with the pups frequently, the 8 often dis- common in this species, both in the wild
couraged them by grunting at them. For and in captivity (Brecht Munn & Munn,
a few days after the death of a neonate 1988), and abandoning the nestbox can be
the 8 was less attentive to the remaining caused by stress or the poor condition of
pups and juveniles began to transport the nest. Twice at Cali Zoo the nestbox
them from one place to another. Some was kept dry by periodically adding sand
juveniles did show excessive carrying and it was not abandoned. Excessive
behaviour that can harm pups and they moisture in the nestbox, caused by inad-
were removed from the group. equate drainage, was the main reason for
With each litter this pair of Giant river abandoning it. Moisture is harmful to
otters has improved their rearing tech- pups as it can cause bacterial infection
niques. The parents have become calmer from Acinetobacter calcoaceticus, Escher-

370                                                                                 THE DEVELOPING ZOO WORLD

Fig. 6. Growth curve for Giant river otter pups during the first 3 months of life (n2).

ichia coli and Aeromonas hydrophila. Such                  Baker, A. J., Baker, A. M. & Thompson, K. V.
infection resulted in the death of two neo-                (1996): Parental care in captive mammals. In Wild
                                                           mammals in captivity: 497–511. Kleiman, D. G.,
nates from litter 6. Aeromonas hydrophila                  Allen, M. E., Thompson, K. V. & Lumpkin, S.
is a bacterium associated with moisture.                   (Eds). Chicago, IL: The University of Chicago Press.
                                                           Bateman, H. (2003): Reproduction in otters:
ACKNOWLEDGEMENTS                                           characterization and assessment 6. Cincinnati, OH:
                                                           Center for Conservation and Research of Endan-
We would like to express our appreciation to Pierre
Gay, Director, Zoo de Doué, Doué la Fontaine,            gered Wildlife (CREW).
France, for his financial support, which enabled us        Brecht Munn, M. & Munn, C. A. (1988): The
to carry out this study. We would also like to thank       Amazon’s gregarious giant otters. Animal Kingdom
Sheila Sykes-Gatz for her opportune advice on hus-         91(5): 34–41.
bandry and management of the Giant river otters,           Carter, S. K. & Rosas, F. C. W. (1997): Biology
and for reviewing this paper. We are also grateful to      and conservation of the giant otter Pteronura brasi-
the staff of Cali Zoo, particularly to the caretakers      liensis. Mammal Review 27(1): 1–26.
Alex Laso, Elianet and Jacobo Becerra, the veteri-         Duplaix-Hall, N. (1975): River otters in captivity:
narian Delio Orjuela, the nutritionist Gustavo Cai-        a review. In Breeding endangered species in captivity:
cedo and the zoo technician Carolina Hartmann, for         315–327. Martin, R. D. (Ed.). London: Academic
their continued collaboration. We also thank Maur-         Press.
icio Guizao for drawing Fig. 2.                            Flu»gger, M. (1997): Haltung, zucht und erkran-
                                                           kungen von riesenottern (Pteronura brasiliensis) in
                                                           Carl Hagenbecks Tierpark. Verhandlungsbericht ber
PRODUCTS MENTIONED IN THE TEXT
                                                           Erkrankungen Zootiere 38: 125–130.
Amikin: amikacin sulphate antibiotic injection,            Foster-Turley, P., Macdonald, S. & Mason, C.
manufactured by Bristol-Myers Squibb, New York,            (1990): Otters: an action plan for their conservation.
NY 10154, USA.                                             Gland: IUCN.
Cefazolina: cephalosporin antibiotic injection, manu-      Hagenbeck, C. & Wu»nnemann, K. (1992): Breeding
factured by Bristol-Myers Squibb/Mead Johnson,             the giant otter Pteronura brasiliensis at Carl Hag-
New York, NY 10154, USA.                                   enbeck Tierpark. International Zoo Yearbook 31:
                                                           240–245.
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