How to Manage the Eurasion Otter (Lutra lutra) in Captivity

The Eurasian otter is a medium-sized semi-aquatic carnivore. It can consume large quantities of food in relation to its size. The otter is a predatory species feeding on fish and sometimes amphibians and requires more energy than other carnivores. The otter’s diet composition and amount can change seasonally. For example, the seasonal dietary needs of the otter will fluctuate by almost 25% between summer and winter (more in winter and less in summer). Their daily diet intake in winter can be up to 15% of its body weight. These large changes in seasonal diet can make adequate energy supply difficult for zoo keepers. Zoo Keepers not only have to look at the dietary intake but also how digestive efficiency changes seasonally. 

Breeding changes can also have an impact on energy intake in the animal. For example, a lactating female Eurasian Otter will consume up to 28% of its body weight daily. 

Breeding Changes and Food Requirements

The amount of energy an animal requires will generally increase during pregnancy and lactation. In late gestation (pregnancy) feed intake may decrease, due to the high levels of estrogens in the body affecting metabolism. The increased size of the foetus will also reduce the volume in the abdominal cavity for storing food. 

During peak lactation, an animal’s energy requirements is at its highest. Now body reserves are being used to meet this increased energy demand.

WATERING

Containers or troughs used by multiple numbers of animals should provide sufficient room (access) so that there is not any great degree of competition between the animals for the water - this is particularly important on days of high water need (i.e. very hot days), or with more aggressive animals.  

Water containers/sources should also be placed in suitable position where they are stable (not easily dislodged or knocked over), where they will not be contaminated by debris or animal droppings falling into them, and easily accessed by both the animals to drink, and whoever is filling them. For some animals, the containers may need to be placed in a position that provides some degree of shelter and/or protection from other animals. Placing water in a position sheltered from the sun will also reduce evaporation rates.  Ideally at least two or, depending on the space available and animals you are watering, possibly more separate containers should be available in case one becomes fouled or is knocked over. 

BEHAVIOUR

It is assumed that all animal behaviour is an adaptation designed to support survival, either directly or indirectly. However, this is not always the case. Animals can behave self-destructively, out of habit, or out of boredom, just as humans can. Captive carnivores are at risk of developing such detrimental behaviours so it is important to understand what motivates these behaviours.

Stereotypies (Zoochosis) is a term used to describe repetitive and apparently obsessive behaviour in zoo animals, or animals in artificial environments with little stimulation. It can result in a range of abnormal behaviours, such as:

  • Tongue playing – where the animal continually licks bars, gates or the wall. Often seen in giraffes and camels.
  • Bar biting – repeated biting or rubbing of the mouth around the bars of an enclosure until it damages the mouth and teeth. This is often seen in bears.
  • Neck twisting – where the animal unnatural twists and rolls its neck. Often seen in monkeys, llamas and giraffes.
  • Pacing – where the animal walks back and forth along the same path. Often seen in big cats such as lions.
  • Circling – is another form of pacing, where the animal places its feet in the same position each time. This is often seen in bears and elephants.
  • Vomiting – where an animal will repeatedly vomit, then eat the vomit. This is often seen in chimpanzees and gorillas.
  • Coprophagia – the eating of faeces, often seen in captive gorillas and chimpanzees.
  • Rocking – where the animal rocks backwards and forwards over and over. This is a recognised symptom in human mental illness and can be displayed in some animals, such as chimpanzees.
  • Swaying - another behaviour also seen in humans with mental illness and can be seen in elephants and bears.
  • Over-grooming - where the animal grooms itself to such an extent that it leaves bald patches where there is no fur or feathers, and often causes ulcers and broken skin.
  • Self-injury and self-mutilation - where the animal inflicts physical harm on itself, such as biting or chewing its tail or leg, hitting its head against a wall, etc. Rhesus monkeys have been observed slapping, rubbing, biting and clasping themselves. Their self-aggression levels rise when they are put into stressful situations, such as moving from one cage to another, and impoverished environments.

Some zoos have developed criteria for assessing an animal’s welfare. These include:

  • Is the animal displaying abnormal behaviour? This may include stereotypical pacing, abnormal aggression or self-harm
  • Does the animal display a wide range of behaviours? Does it partake in a variety of activities throughout the day?
  • Does the animal show a relaxed demeanour when resting? Or does the animal seem tense and on guard?

These simple observations made by the animal’s handler can highlight issues of mental wellbeing. Of course, the handler or zookeeper needs to be familiar with the animal’s normal behaviour to be able to identify the abnormal.

Behaviour Management
The staff members that oversee the care of captive carnivores are most likely to be at the centre of a behaviour management program. They observe and provide care for the animals daily and provide feedback to team managers and specialists. They will be the ones responsible for working with environmental enrichment apparatus. They set up and maintain these forms of environmental enrichment and provide feedback on its effectiveness. 

Environmental Influences on Behaviour
Often, changes must be made that can impact the behaviour of the animals.  This could be changing of group sizes, moving animals between enclosures or separating animals temporarily. Much research has been undertaken on the effect of change on primate species. These can be changes to the physical or social environment of animals and can include physical and social changes.

Physical Changes
One of the main physical changes that animals in zoos undergo is relocation to new enclosures. Large cats may undertake stereotypical pacing and increased cortisol hormone levels in urine when moved to new enclosures without places to hide or climb. 

Other changes may be more positive, such as changing to more natural enclosures.  Some researchers have noticed more wild-like behaviour when animals are provided with more free-ranging enclosures. However, this is not always the case and naturalistic enclosures may not necessarily improve the mental wellbeing of an animal.

Social Changes 
Changes to group composition occur regularly due to births, deaths and the transfer of animals between zoos. Much research has again gone into the effect of social changes on primate groups. Changes to the behaviour of animals can occur when individuals are removed from established groups, new animals are introduced to established groups or the creation of new groups. 

These changes can have a range of effects on the animals within the social groupings. Stereotypical behaviours may appear when mates are removed, aggressive behaviour can be directed at the offspring of removed animals within a social group and the introduction of animals into an established group can lead to initial stereotypical behaviours which may later subside.

Social changes are quite often undertaken to benefit animals. For example, at Houston Zoo, Maned Wolf males were removed from enclosures when the female was giving birth. They were then reintroduced in stages under supervision which helped to enhance the acceptance of the cubs by the fathers.