Caring for Selected Otter Species (Asian small-clawed, Cape ...

CHAPTER 5: Social Environment
Group Structure and Size
Careful consideration should be given to ensure that animal group structures and sizes meet the social,
physical, and psychological well-being of those animals and facilitate species-appropriate behaviors.
A. cinereus: In captivity, Asian small-clawed otters are monogamous, with both members of the pair
helping to raise the offspring. Unlike L. canadensis, the otter parents and offspring should be housed together.
Older siblings help raise the younger ones, and a family group or breeding pair can produce two litters a year, with
up to seven pups in each litter. Similar sized groups are sometimes found in the wild (Foster-Turley 1990). It is
recommended that these otters be held in adult pairs, adult pairs with offspring, or single sex groups. The size of
the group will depend on the size of the exhibit and the compatibility of the individual animals (Lombardi et al.
1998). The formation of single sex groups should be accomplished at a very young age to avoid aggression.
A. capensis: A. capensis have been observed in multiple social situations. In fresh water inland systems,
the male stays with the female and offspring (Rowe-Rowe 1978). Clans up to 10-15 individuals have been
observed. In marine ecosystems, it has been noted that the male does not stay with the family group (Estes 1989).
Females with pups are the typical family group (Chanin 1985), but this species is often seen alone (Chanin 1985). In
captivity, pairs have been separated during parturition and early pup rearing. This species has been held in pairs
and in groups of 1.2 in captivity (Reed-Smith & Polechla 2002).
L. canadensis: L. canadensis are believed to be more social than most other mustelids (but not as social as
some of the other otters), based on the findings of a number of researchers (Beckel 1982; Rock et al. 1994; Testa
et al. 1994; Johnson & Berkley 1999; Blundell et al. 2002a,b; Gorman et al. 2006, M. Ben-David, personal
communication; S. Shannon, personal communication). For example, Stevens & Serfass (2008) documented that
out of 172 film documentations of otters using latrines, 59.3% were by single otters, 19.2% were by two otters,
17.4% were by three otters, and 4.1% were by four otters.
A variety of social groupings have been documented, but, in general, the following are most typical:
female with offspring; lone male; group of males; lone female; group of males with sub-adult females; pair (during
mating season only); or two females with offspring. Male groups have been reported by Blundell et al. (2002a,
2002b, 2004) and Hansen (2004); female groups were recorded by Gorman et al. (2006)
Otter associations may vary with the habitat in which the animals are found. Blundell et al. (2002a, and b)
found otters living in areas rich in resources seem to show more of a tendency to socialize, particularly the males
and sub-adult females. Discounting female and pup associations, the Blundell et al. (2002a, and b) telemetry study
found that females were asocial in 47% of their locations, while males were asocial during only 24% of their
locations. Further, they determined that among the “social” otters, males were social in 46% of their locations and
63% of that time was spent in all male groupings. “Social” females were located in social groupings only 26% of the
time, and 78% of that time they were located in mixed-sex groupings (Blundell et al. 2002a and b).
Gorman et al. (2006) found in Minnesota that annual home ranges for males were 3.2 times greater than
for females and annual core areas for males were 2.9 times greater than for females. Core areas frequently
overlapped with interactions between overlapping resident females and males most common (51.7%) while malemale
(27.6%) and female-female (20.7%) interactions were slightly less frequent. Female core areas overlapped
those of other females 22.2% of the time and males 15.8% of the time; male core areas overlapped with those of
other males, on average, 15.7% of the time. They concluded that river otters living in the upper Mississippi
watershed, “exhibited clear evidence of space sharing, suggesting that individuals in this population were neither
solitary nor territorial….[otters] appeared to socialize to some degree with any individual for which they had an
encounter opportunity.”
Zoos and aquaria would qualify as “habitats rich in resources”, thus providing the opportunity to keep
more social groupings of this species, as found in some portions of their range. Ben-David et al. (2000, 2001a, and
b) maintained 15 unrelated males in one enclosure for 10 months with little to no problem.
There are no minimum or optimum group sizes for this species. To the contrary, this species’ behavioral
plasticity allows the formation of social groups not normally associated with a typically solitary species. Preferred
groupings include: multiple males, a male-female pair, one male and multiple females (1.2), multiple pairs (2.2).
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