MINIMUM AZA GUIDELINES FOR KEEPING
HYENAS AND AARDWOLVES IN CAPTIVITY
Alan Shoemaker Riverbanks Zoological Park
PO Box 1060
Columbia , SC 29202
Cincinnati Zoo and Botanical Garden
3400 Vine St.
Cincinnati, OH 45220.
The family Hyaenidae includes four species, three of which are heavy set, dog-like carnivores that possess similar husbandry needs. For purposes of this discussion, there are three species of hyena: the striped or common hyena, Hyaena hyaena; brown hyena, H. brunnea; and spotted hyena, Crocuta crocuta. An additional hyaenid, the aardwolf, Proteles cristatus, is represented as a mono-specific genus which, because of its unique morphology and insectivorous diet, is considered unique enough by some to be placed within its own Family, Protelidae. In view of its external similarity to the striped hyena as well as limited acceptance of this separate family (Corbet and Hill, 1991), aardwolves will also be included in this discussion.
With one exception, hyaenids are solitary carnivores that function near the top of their tropic level. While this behavior will permit the solitary species to be housed singly, it also requires that the introduction of potential mates be done carefully to prevent fighting, injury, or death.
Their aggressive nature and physical capabilities demand that owners exercise the utmost care when designing cages or exhibits for any species, regardless of size, to insure that specimens cannot escape or reach into adjacent cages, keeper or public areas. Caution also should be exercised when handling otherwise "tame" or hand-raised individuals.
Some aspects of captive management for both hyenas and
aardwolves are similar, and are
discussed below. Requirements unique to one or the other of the two groups are listed
1.Temperature: Although hyenas and aardwolves
may originate from tropical climates,
most are tolerant of a wide range of temperatures, at least during daylight hours.
Animals kept outside should always have access to shade, especially during warmer
parts of the year. When acclimated, most species without young require only minimal
shelter at night, although heated shelter may be needed for animals kept in northern
Aardwolves may be kept outside
if they have access to a nest box with heat lamps, or
an artificial cave containing heated floor pads. In such cases, they do well when nightly
lows reach 32 degrees F (0 degrees C) without experiencing any adverse results.
When housed indoors, all hyaenids should be protected from temperatures exceeding
85 degrees F (30 degrees C).
Indoor exhibits should have
10-15 air changes per hour of non-recirculated air. A
relative humidity of 30-70% is reasonable for this species. If kept indoors, a separate
ventilation system or solid glass barrier separating them from visitors may be advisable
in order to reduce the strong odor produced by their anal glands as well as to protect
them from the threat of disease transmission.
2.Water: Fresh clean water for drinking should
be available at all times, and can be
accomplished by using a Lixit, a sturdy portable water container firmly attached to a
wall or an exhibit built-in, i.e. a small shallow pool or stream (spotted hyenas frolic in
tanks 3 feet deep). Regardless of size, water containers should be cleaned and
disinfected daily. Many hyenas enjoy bathing and shallow pools should be
incorporated into outside exhibits, as appropriate.
3.Sanitation: Hard-surface primary enclosures
and food containers (if used) should be
cleaned daily and disinfected with detergent and disinfectant. Logs and play objects
should be included in this regime. Dirt substrates in outdoor exhibits should be raked
and spot-cleaned daily. Foot baths containing appropriate disinfectants should be
used prior to entering all hyaenid enclosures, or areas containing enclosures, and their
use strictly adhered to by all personnel.
4.Veterinary Care: Services of a knowledgeable
veterinarian should be available prior
to obtaining any hyaenid. Periodic (at least twice annually) fecal examinations should
be performed to monitor and treat parasite infestation. A physical exam should be
performed annually and the results recorded. When the opportunity arises, animals
should be tattooed on the inner aspect of the thigh with either the studbook or
accession (ISIS) number, or receive an transponder implant.
The degree of susceptibility
of the Hyaenidae to viruses commonly impacting canids
and felids is not well understood, and many practices are based upon successes with
other carnivore species. Taxonomically hyaenids are more closely related to felids
than canids. Most carnivores should receive Fromm D canine distemper of embryo
origin that derive from modified live virus (MLV) products. Although opinions vary,
annual vaccinations should probably include prophylaxis against both canine
distemper, a paramyxovirus, and feline distemper, a parvovirus (Berger et al, 1992).
The large colony of spotted hyenas maintained at the Univ. of California-Berkeley for
10 years are vaccinated against canine distemper, the adults on an annual basis, the
young at 2, 3, 4 and 12 month intervals (Berger, et al, 1992). Berger et al (1992) also
recommend protection against rabies. Only killed virus (KV) rabies products are
recommended (Berger et al, 1992).
Like the poorly understood
nature of viral susceptibility impacting hyaenids, the use of
modified live virus (MLV) products versus killed virus products varies among
practitioners. Rettig and Divers (1986) prefers MLV products on viverrids for more
reliable protection while Berger et al (1992) uses KV products to minimize the
possibility of vaccine induced viral infection. Given the endangered status of one
hyaenid, coupled with the increased scarcity of others from wild or captive born
sources, KV products are probably the safer of the two approaches even if more
frequent levels of vaccination are required. For more information, owners should
consult Fowler (1986) and Berger et al (1992).
Primiparous females frequently
experience dystocia and should be monitored closely
at birth (Berger et al, 1992). Impending birth may often be recognized by the pregnant
female's refusal to eat, or by frequent urination and spotty defecation.
For purposes of the following discussions, hyaenids are
divided into two groups: the true
hyenas and the aardwolf. These are based on husbandry and behavioral needs, and
taxonomic relationship should not be inferred.
Hyenas are large, dog-sized
carnivores well adapted to a scavenging mode of
existence. Their massive jaws and teeth are unusually capable of cracking large leg
bones and ribs, and smaller bones are commonly ingested whole. Adults have a head
and body length of 41-54", a tail length of 7-10", a shoulder height of 23-37", and an
average weight of 55-135 lb. Obesity can be a problem among female spotted hyenas
in captivity, some overweight individuals exceeding 150 lb. Brown hyenas are the
smallest of the three species while female spotted hyenas are 10% heavier than males.
Also, the genitalia of female spotted hyenas mimics that of the male. The clitoris is
large and highly erectile, and two sacks containing fibrous tissue closely resemble a
scrotum and are located in the same area.
Although very hardy under
the simplest of husbandry regimes, hyena exhibits must be
stout enough to withstand their destructive tendencies. Longevities exceeding 20 years
are not uncommon. Spotted hyenas have reached 41 years of age (Jones, 1982) and
brown hyenas 30 years (Shoemaker, 1992).
do well on felid diets that are based on beef or horse products.
Diets of this type that already have the appropriate vitamins and minerals added
may be obtained from commercial sources. Similar diets may also be prepared
in-house. Whole animal carcasses (rodents, rabbits, or fowl) freshly killed or
thawed, may be substituted upon occasion to vary the diet. Because of
problems with obesity, hyenas may be fasted one or two days a week.
In the past, some owners fed hyenas muscle meat from freshly butchered
livestock. Although this source of feed is still used occasionally, practitioners
are cautioned that diets consisting primarily of whole or ground muscle meat
may be inadequate in vitamin/mineral content. Owners should also be wary of
carcasses obtained from road kills or donations because of the potential for
contamination. Feed animals from such sources should be inspected to insure
that they are free of disease. Diets containing high percentages of fowl,
including chicken or turkey necks, should be avoided because of inadequate
levels of calcium and phosphorous.
When more than one animal is maintained within the same cage, at least
feeding areas should be used to reduce aggression. Because hyenas are highly
adapted to consuming bones, successful breeders recommend including several
bones in their diet every day (Berger and Frank, 1992). Beef and sheep are
best; where available, pig bones will suffice if frozen to prevent trichinosis. All
bones are crushed and ingested without difficulty.
Young can be hand raised on milk formulas that are developed for kittens.
Berkeley, neonates are fed 70 ml of formula four times a day, gradually
changing to 200 ml of formula twice a day (Berger et al, 1992).
Hyenas are kept in both indoor and outdoor situations.
Normally active animals with large territories, a single specimen should have at
least 200 square feet, and should be increased by 50% for each additional
animal. Indoor exhibits may employ combinations of glass, gunite, solid
masonry products, or bars for barriers, the last requiring adequate space to
protect the public from being bitten. They may also be kept outdoors in moated
exhibits that have a retaining wall, or behind 9 gauge chain link fencing.
Although not good jumpers or climbers, hyenas swim well and are prodigious
diggers, and as a special precaution, chain link fencing should extended 3 feet
(1 meter) into the ground and extended at least 42 inches (1.2 meters)
horizontally into the exhibit.
Because of their nocturnal habits, particularly striped and brown hyenas,
box or cave should be provided for sleeping needs. Periodic feeding of small
items will stimulate activity during daylight (visitor) hours, and stereotypic
behavior can be reduced or avoided by the addition rocks, trees, and other
impervious objects which can be periodically replaced to increase interest.
Hyenas vary widely in their social needs, and groups should be
developed according to the behavioral characteristics of each species. Because
female spotted hyenas are larger than males, they dominate them in competitive
situations. Spotted hyenas are also the most social of the three species and can
be kept in groups containing several members of both genders if specimens are
obtained when young. A group containing 5-6 adults is probably as large as
can be maintained without too much aggression developing, or causing ultimate
injury to the lowest ranking individual (L. Frank, pers.comm.).
Once a group has become stable and its members' social ranking established,
is not wise to remove individuals from the group unless absolutely necessary.
Adult females are especially intolerant of other females and fighting may
develop even after only brief separations. In order to maintain the status quo,
medical treatment should be conservative when possible. Indeed, it is "routine"
for subordinates to have bite wounds about their shoulders and ears but due to
their particularly thick skin, such injuries are usually superficial.
Striped and brown hyenas are more solitary and do best when kept in pairs.
Although establishing pairs of striped hyenas is generally easy, the female being
dominant over the male, establishing a pair of brown hyenas can be difficult.
Brown hyenas have a unique social order in nature that is seldom broken in
captivity (Mills, 1982; Owens and Owens, 1979). In nature some young males
leave the "clan" to live solitary lives. Other males remain with their natal group.
Those males that remain with the natal clan become non-breeders, tolerating
periodic visits of nomadic males. Conversely, nomadic males periodically visit
various clans to breed with estrus females. In captivity, most males assume the
role of a clan male. If breeding does occur, reproduction usually ceases long
before either animal is old, the male showing little interest in mating.
Females of all species have 1 - 3 young per litter. It is common for spotted
hyenas to rear only one young at a time, the largest cub often killing the smaller
ones. An isolated cubbing den should be provided for females approaching
parturition, and escape tunnels are useful when young spotted hyenas are being
introduced to their dam's clan. Gestation is 90-110 days, the spotted hyena
having the longest gestation.
raised hyenas may become very tame toward humans. Never
the less, they are very capable of injuring their owners and care should be
taken before entering the cage of such animals.
The aardwolf is the smallest
member of the Hyaenidae, having a head and body length
of 21-31", a tail length of 8-12", and standing 17-19" at the shoulder (Novak and
Paradiso, 1983). Adults weigh 15-22 lb. The body hair is rather long and coarse, and
those on top of the neck and back can be erected during times of excitement or when
the animals are startled to make the animal appear much larger than normal.
Aardwolves are capable of making loud growls or roars which, when coupled with
mane erection, make them appear quite formidable. Though used primarily as a means
of marking their territory, a foul smelling odor can be ejected from anal glands in
The aardwolf is primarily
an insectivore, feeding on termites and ants. Unlike hyenas
which have immensely powerful jaws and up to 34 teeth, the aardwolf has weak jaws
that contain only widely spaced, vestigial cheek teeth. Only the canines of their 24
teeth remain "normal" in size, the others appearing to be of little use. The canines are
sharp and pointed, and are probably used for defense and in social interactions
(Nowak and Paradiso, 1983).
In the wild aardwolves inhabit
open, sandy plains or bush country. When not in search
of food, they spend the day in underground dens, often taking over burrows
abandoned by aardvarks, Orycteropus afer, or crested porcupines, Hystrix
africaeaustralis (Nowak and Paradiso, 1983). Though generally found as single
animals or in pairs, there have been occasions where family groups of up to six
animals have been observed. After a gestation period of 90 - 100 days, a litter of 2-3
(range 1-5) young are born in the under-ground den site.
1.Diet: Due to
the shear numbers of insects consumed in the wild, captive
aardwolves, like other insectivorous mammals, should be fed a palatable,
high-protein gruel. A mixture of ground meats, dry and/or canned dog food,
and evaporated milk, supplemented with vitamins, is used by most institutions
maintaining this species. Because of the high caloric content of meat-based
diets in comparison to natural ones comprised primarily of insects, captive
aardwolves may become overweight unless the diet is monitored carefully.
Being the size of a medium-sized dog, aardwolves do not need a
large exhibit. Because of their general shyness, however, priority should be
given to the number of hiding places included within the exhibit. For a pair of
adults, housing should measure at least 10 feet by 10 feet as long as it contains
1-3 nest boxes, dens, or caves, although larger enclosures may be necessary
for some pairing because of compatibility problems.
Aardwolves do not seem able to jump more than a few feet off the ground,
do not climb well. When kept outside, a shallow dry moat or low (6 feet/2
meter) wall is usually enough to keep them contained. Aardwolves are
prodigious diggers and this form of behavior should be considered if the
animals are to be on natural substrate. Chain link fencing buried three feet into
the ground and then extending three feet into the enclosure should be adequate
to handle this situation.
Depending on enclosure size, aardwolves can be housed
singly, in pairs, as single sexed small groups, or as extended family groups.
Because some pairs will not be compatible, facilities planning on breeding this
species should be prepared to try several combinations. Unlike husbandry
techniques commonly employed when breeding other carnivores, it is not
always necessary to separate male aardwolves from females prior to
parturition. Males often act as protectors of the "nursery" den. Gestation
averages 90 - 100 days (Nowak, 1983).
are predominantly crepuscular or nocturnal. They can
be kept indoors using reversed light cycles to stimulate activity during peak
visitor hours. Facilities keeping this species in outdoor exhibits will see the bulk
of their animal activity at dawn and dusk, with little being observed during
Berger, D.M.P.; Frank, L.G. and S.E. Glickman 1992. Unraveling ancient
mysteries: Biology, behavior, and captive management of the spotted hyena,
Crocuta crocuta. 1992 PROCEEDINGS JOINT MEETING
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SPECIES, THIRD EDITION. Oxford University Press, London.
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Fowler, M. 1986. ZOO ANIMAL MEDICINE, W.B. Saunders Co., Phila.,
Jones, M. 1982. Longevity in captive mammals. DER ZOOLOGISCHE
GARTEN. 52: 113-128.
Mills, M.G.L. 1982. The mating system of the brown hyaena, Hyaena
brunnea, in the southern Kalahari. BEHAVIORAL ECOLOGY AND
Owens, D.D. and M.J. Owens 1979 Communal denning and clan associations
in brown hyenas (Hyaena brunnea Thunberg) of the central Kalahari Desert.
AFRICA JOURNAL OF ECOLOGY. 17:35-44.
Nowak, R.M. and J.L. Paradiso 1983. WALKER'S MAMMALS OF THE
WORLD. The Johns Hopkins University Press, Baltimore and London.
Rettig, T. and B.J. Divers 1986. Viverridae. ZOO ANIMAL MEDICINE, M.
Shoemaker, A.H. 1992 1992 INTERNATIONAL BROWN HYENA
STUDBOOK. Riverbanks Zoological Park, Columbia, SC 25 pp.
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