International Giant Otter Studbook Husbandry and Management

It does not contain small rocks, gravel, or pebbles throughout. Otters can effectively groom and
easily dig on/into the surface of this soil throughout their enclosures and they can dig deep into
hillsides made of this furnishing. It can retain these qualities, with/without vegetation, and
function very effectively within a giant otter enclosure for many years with only some natural
erosion of the hillsides over the years. At least one zoo (Brasilia Zoo) is known to have
successfully used this soil for many years (see the paragraph below). These qualities therefore
are those that a soil should possess to be considered an appropriate/effective soil type for
Pteronura enclosures. This soil type can also support many underground dens that are naturally
dug by giant otters and giant otters can successfully rear their cubs in the dens. (See Chapter 2
Section 12 and below.) This substrate type is also therefore an optimal soil type for giant otter
enclosures. Because the successful soil types used in some of the South American zoos are
obviously not available for use in every enclosure, research should be conducted to identify
appropriate and optimal soil types that can be provided in enclosures world-wide. (The
functional soil types now used should be identified by scientific classification so their properties
can be more closely studied and compared with other soils and so they can be recommended for
use.) Soil types recommended should offer the same/similar qualities as those successful soils.
Mixing soft sand with soft soil may help loosen a soil’s texture, although this technique has not
been tried and it is unknown at this time if it would be appropriate for use.
Non-ferric Red Latosol forms the approx. 2 m (6.56 ft) high (and higher) 40-45 o angle
extensive hillsides and land area within Brasilia Zoo’s expansive giant otter enclosures. Over
the many years the hillsides at this institution are slowly reducing in size and degree of angle
because of natural erosion and continual digging. The otters although, are still able to
effectively use the hillsides for daily terrestrial activities, underground den building, and cubrearing.
This soil remains loose in texture, even though it is exposed to full sun and hot
Brazilian temperatures. When it is completely dry it easily breaks apart into tiny
grains/particles that either are sand like-in appearance or are actually sand particles, as the soil
contains sand. This quality seems to make it a very successful substrate for otters to groom and
dig on/into the surface and dig deep into. This is also probably the quality that makes the soil
drain well. This soil type can have an approximately 53% clay content. The clay content may
help prevent underground dens from caving in. (A soil must not have so much clay that water
can not drain easily.)
“Latosol: A soil class in the Brazilian Soil Classification System. Latosols are very deep, very
well drained, homogeneous and highly weathered and leached soils. They tend to have medium
to very high clay contents... These soils are similar to non-aquic Oxisols in soil taxonomy...
Non-ferric Red Latosols are abundant all over the Cerrado [this area includes Brasilia]. Nonferric
Red Latosols are quite variable in texture, which ranges from medium to very clayey.
[They can have a] 53% clay content....Texture: [means] The proportion of sand, silt, and clay
in a soil. Very clayey soils have more than 60% clay. Clayey soils have between 35 and 60%
clay. Silty soils have more than 65% silt and sandy soils more than 70 or 85% sand. Medium
textured soils have approximately equal amounts of sand, silt and clay.”
(http://www.dcs.ufla.br/cerrado/cerrado2.htm internet site 2003).
Giant otters found in the wild near Brasilia Zoo likely use/used this soil type (Latosol) for den
building as well. In the wild giant otters will use a variety of soil types to dig their underground
dens within. They will use soil that has a significant clay content as well as sandy soils and
other types. For example, “While sandy soils cave in more often they are still used and the dens
[den] is repaired until it is abandoned.” (Duplaix 1980).
88