International Giant Otter Studbook Husbandry and Management

of course, because information regarding these issues is so limited, specific conclusions can not
be drawn. Males have been able to breed successfully at 14 years of age. This occurred with at
least two males in two institutions (Brasilia Zoo & Hagenbecks Tierpark). It is crucial that
research be continued on these matters and that zoos record in detail and openly share their
reproduction information. (See the earliest age of breeding and reproduction below.)
At Hagenbeck “The number of cubs per litter varied from 1 to 6. Most of the litters consisted of
2 - 4 cubs. There were 2 litters with 5 cubs and 1 litter with 6 cubs.” (Wünnemann 1995 b ). At
Brasilia Zoo, 5 cubs in one litter all survived (i.e. to one year of age or older).
A historical survey on litter births in zoos world-wide revealed that litter size (n=31-where the
litter size was known) ranged from 1 to 6 cubs, with a mean of 2.9 and common litter size of 2
cubs (Sykes-Gatz 2001, Sykes-Gatz 1998/2002). See cub rearing success under Chapter 1.
Cub Development in Captivity
Information on physical and behavioral cub development is limited because parents
rearing cubs must not be disturbed by humans except for when it is necessary to ensure
the survival of the otters (i.e. during emergencies, vaccinations, or necessary medical care).
Information on parental care, cub development and behavior has been gathered by monitoring
otters with videocameras and microphones or from hidden viewing areas. See Chapter 2
Section 10B for these monitoring methods. Following are the most thoroughly documented and
available records of cub development at this time.
Nursing in Very Young Cubs:
At Dortmund Zoo very young giant otter cubs, being reared by their parents from birth to at
least 7 days old when the last cub was pulled for handrearing, nursed frequently during each
hour of the day (Sykes-Gatz, pers. obs. 2002). (The last cub was handreared from 7 days old to
11 days old when it died because of a malfunctioning thyroid gland. This cub although
appeared to be at a healthy weight (but it was significantly injured) when it was pulled for
handrearing and its hunger seemed to be satisfied when it was with its parents. See Chapter 1
Sections 2 & 4 for more information on malfunctioning thyroids.) It was much easier to
determine when cubs were actually nursing with auditory monitoring (in connection with the
video monitoring), because they made from the first day of birth, “nursing hums” when they
were suckling. This hum is a somewhat higher pitched and faster vocalization than the contact
hum (described in Duplaix 1980). It is also unlike the contact hum in that it has a twittering
quality to it and it was only performed when the cub was actually suckling. It was performed
both when the cub was nursing from the mother and the handrearer’s bottle. (When replicated
by the handrearer, it can encourage cubs to feed.) The cubs also displayed “tail wagging” when
they nursed (from the first day of birth) from the mother and nursed from the handrearer’s
bottle. The cubs wagged their tails, rather quickly and repeatedly, from side to side (i.e.
horizontally, but not vertically/up and down), when they suckled. The tip of the tail can also be
kept raised upwards while wagging. (Note: sometimes when the cub might be anxious to nurse
or immediately preparing for nursing it might wag its tail.) This behavior is different from the
“tail waving” that is described by Duplaix (1980) in that it is performed during nursing only
(except during the situations mentioned above) from the first day of birth and the tail only
moves horizontally in direction. The “nursing hums” and “tail wagging” behaviors are not
known to have been described before in literature and the descriptions and terms in quotes are
originally made by Sykes-Gatz (pers. obs., unpublished reports 1999-2002).
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