Giant Otter

Did you know?
Giant otters are land mammals that swim. They are semi-aquatic, not aquatic, and are dependent on the land and water to survive, but spend more time on land. E.g. as instinctively avid diggers and groomers, digging, both deep and shallow, and grooming in soft loose natural substrates are among their most favored and most frequently performed terrestrial activities in zoos and they use nearly their entire land area to carry them out. In zoos, they do this to exercise, play, mark territories, reduce/prevent stress and to help clean/dry themselves with loosened substrates.

Photo Copyright by
David Monniaux

Why do zoos keep this animal

Giant otters in zoos can play an important role to raise public awareness about this endangered species and its habitat. Studies in zoos have contributed to overall knowledge and to the development and improvement of conservation/management strategies for wild populations. E.g., because very few field studies exist, research on life history data of zoo animals is used as a reference source for this species in the wild.

How this animal should be kept

The total minimum size enclosure for one giant otter pair should be at least 240m² and when indoor enclosures are needed, they should be a minimum of 75m² of the total area. In temperate climates, it is necessary that an outdoor enclosure (with or without heated outdoor water) provides access to a heated indoor enclosure. Both indoor and outdoor enclosures require the same recommended conditions (i.e. land to water ratios, substrates etc.). At least 2 dens (i.e. separable rooms) to contain nestboxes/briefly hold animals should be provided and at least 2-3 nestboxes (or natural underground dens) are needed.

Providing, within all enclosures, the recommended land to water area ratios (i.e. enough land area), substrate types and depths to cover all surfaces, and deep digging area sizes, is just as important as the need to provide a swim area. These are among the most crucial husbandry provisions needed to maintain otter physical and behavioral health and they are also necessary to promote successful cub-rearing and adjustment to new/unusual situations. To meet these needs, nearly the entire enclosure surface area, including dens and nestboxes, must keep sufficiently dry, soft, and sanitary and otters need to be able to effectively dig and groom throughout that entire area. The enclosure must also offer a sufficient proportion of land, deep digging, and water area. The provisions in the two paragraphs below are essential to providing these conditions.

Different enclosure sizes require different land to water area ratios. As enclosure sizes decrease below 240m², proportionately increased land area sizes are needed. It is necessary to provide, within each indoor and outdoor enclosure, at least the minimum percentage land area that the following formula determines. For every 1m² that the (indoor or outdoor) enclosure size is below 240m² multiply that number (without the m² symbol) by 0.1, then add the result to the number 60 and this resulting number is the minimum land area percentage (%) that the (indoor or outdoor) enclosure requires. E.g. a 150m² enclosure requires a minimum of 69% land area and a 75m² enclosure requires at least 76.5% land area. Enclosures between 240m² to 600m² in size require at least 60% land area.

It is crucial that nearly the entire area of surfaces/substrates that otters are directly exposed to are soft, natural, well-draining, not coarse, sufficiently dry and deep, and loose enough so that otters can easily dig into them. It is necessary that every indoor and outdoor enclosure surface is nearly entirely covered with soft pebble-free sand or mulch (i.e. tree bark pieces only), at least 10-20cm in depth, or deep soft loose soil with the needed qualities. The substrates used must not have gravel, pebbles, rocks/stones < 20cm in dia./width, wood chips, or abrasive sand mixed throughout them and if areas of these individual or combined substrates already exist, they should be removed or covered over with at least 60cm of a recommended substrate. Soil should not be used to cover hard or artificial surfaces. Sand and mulch are ideal to cover over any surface/substrate. Many soils are or will become too packed or will not remain dry enough after otters dig, clear vegetation and track water throughout them (these activities must not be prevented). Add new mulch/sand on top of the existing layer (e.g. yearly) to maintain minimum depth/cover broken down mulch. Each indoor and outdoor enclosure also needs at least a 40m² area, where sand or mulch, a minimum of 40-60cm in depth, or soil hillsides, allow for deep digging. The hillsides should be at least 2m high and have an angle no more or less steep than 40-45o.

The following conditions, with the recommended land to water ratios and substrates, are needed to keep surfaces sufficiently dry. In every enclosure, the land area bordering the water area should extend at least 5m in the direction leading away from the water's edge. In enclosures below or ca. 75m² in size, the land area should only be bordered by water on one of its sides and in enclosures ca. 240m² in size, no more than two sides of the land area should be bordered by water. Also, long water area contour lines should not be used in enclosures ca. or below 240m² in size, but varied contour shapes are recommended. Dens and nestboxes should be located at least 3m away from the water's edge.

Pools should have deep areas (at least 100cm deep), shallow areas (which are esp. liked), and must have plentiful areas of gently sloping edges for safe cub exits. Varied natural furnishings, e.g. logs, tree stumps with roots, cut bamboo, boulders, should be placed on land and in and over pools. Thin logs connected with brackets or large sloping rocks placed just behind and bordering pool edges, fence covered drains/filters, and drain pipe extensions help prevent substrates from entering water areas, cleaning and drainage systems. Furnishings must allow otters, esp. cubs and parents, easy and safe pool access and exits. Enclosure designs, furnishings, and husbandry methods that offer visual and acoustic privacy from human disturbances (zoo staff and visitors) during cub-rearing and that allow safe gradual introduction of unfamiliar or temporarily separated otters must be provided. Fish should be fed exclusively. A variety of good quality fresh water fish, low in thiaminase and fat, should be offered as the main diet. Saltwater fish can be offered occasionally.

Excerpts from "International Giant Otter Studbook Husbandry and Management Information and Guidelines (2005)"