International Giant Otter Studbook Husbandry and Management

otters to easily dig into), artificial, continually very damp or wet, slow drying, or poor
draining substrate. Otters must not be directly exposed to any of the following land and
floor substrates within any area of their indoor and outdoor enclosures: areas of small
rocks < approx. 20 cm diameter, gravel, or pebbles (smooth, rounded, or otherwise), areas
of soil, sand, or mulch mixed with any kind of pebbles, gravel, small rocks, construction
sand, or abrasive sand throughout, areas of construction or abrasive sand or any
substrates mixed with these, fence areas, and any other areas of coarse, rough, or abrasive
substrates. Note: soil, sand, or mulch that contains pebbles, gravel, or small rocks
(smooth, rounded, or otherwise) or construction or abrasive sand mixed throughout or any
substrate with many larger rocks throughout is coarse. Builder’s/construction sand is
abrasive/coarse and areas of pebbles, small rocks, or gravel are coarse.
Inefficiencies and problems can also develop when the recommended minimum substrate
depths (i.e. when substrate depths are shallower than recommended) and quality (esp. when
new mulch is not added on top of existing mulch that has broken into small pieces and packed
down) are not maintained. I.e. the substrates can remain very damp/wet and otters cannot
effectively or will not use them, esp. for grooming and digging, and health problems or
abnormalities will develop. (See Parts A-B below.) Problems can develop when the deep
digging area is not sufficient in size; see the recommended minimum size needed in Part B
below. Inappropriate land and water area locations and designs (esp. land to water ratios
that do not provide enough land) and unsuitable locations for nestboxes, dens and areas for
natural underground dens will also cause surfaces to remain wet/very damp or worsen
conditions; see Section 5 below.
It is necessary that nearly the entire base surface area that otters are directly exposed to in
every indoor and outdoor enclosure is soft, well-draining, easily drying, and loose enough
in texture so that otters can effectively groom on (which includes digging and scratching
on/into substrate) and very importantly, easily dig into it. In addition, soil substrates should
not erode easily. At least, the recommended substrate types, quality, and minimum depths to
cover nearly the entire land and floor area and minimum deep digging area size and depth must
be provided in every enclosure (see Part A-B below for more information).
For a significant number of institutions, i.e. primarily those outside of South America,
finding an appropriate soil type that possesses and can retain all of the aforementioned
necessary qualities may be difficult or impossible. (At present the only soil type that can be
recommended for use [i.e. it is known to serve as an appropriate/effective soil] within giant
otter enclosures is Non-Ferric Red Latosol and it is found in Brazil, although most of the soil
types found to exist in nature in South America are likely appropriate for use. See Part B
below. Obviously, many institutions do not have access to these particular soil types.) The
following has to be considered: will the soil become, after continual use, too tightly
packed/compacted for otters to effectively, comfortably, and easily use for all grooming
and digging activities. Soil, with/without vegetation/turf, must remain loose enough that
when otters rub, roll, scratch, and dig on/into its surface to groom themselves, the soil
particles move freely about and the otters can cover their body/fur with the freed soil
particles. Whether the animals are grooming or not, substrates must also allow digging to be
easily carried out throughout nearly the entire enclosure land area. (These activities are
described in Section 3 below.) When soil hillsides are provided for the necessary deep
digging areas, otters must also be able to dig at least 40 cm to 60 cm (16” to 24”) in depth
in these areas. (Even when hills are provided for deep digging, the hillsides cannot be
effectively used when the soil is inadequate.) It also has to be considered if the soil can still
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