Welfare of primates: normal behaviour patterns
All social primate species should display social behaviours, including physical behaviours and vocal and visual displays relevant to the species.
Expectations of normal behaviour
Normal behaviour is that expected of physically and psychologically healthy animals. Changes in behaviour and the presence/absence of particular behaviours can provide a valuable indication of the animal's welfare state.
Keepers should be familiar with the full normal behavioural repertoire of the species and individuals they keep, including facial expressions, vocalisations, postures and activities.
Signs of good and poor welfare amongst primates
Primate keepers should recognise signs of good and poor welfare, as abnormal behaviour can mean disease, injury or stress. They should know what steps to take if signs of poor welfare are observed.
All gregariously social primate species should display social behaviours, including physical behaviours and vocal and visual displays relevant to the species. These include, but are not limited to, social grooming, food sharing, communal resting, and interactive play that's applicable to the species. Primates should be housed in stable groups of suitable size and composition to allow the full expression of these behaviours.
Social interaction and primates
Social interaction with companions of the same species not only provides essential stimulation and learning opportunities, but it also provides a source of comfort, reassurance and enjoyment. Removing a primate from its family or social group may have adverse psychological, emotional and physical welfare implications for the individual, and for the remaining primates. This is particularly so for an infant and its mother, and for species forming pair bonds.
Social grooming is an extremely important behaviour, as it maintains and strengthens social bonds, provides a source of comfort and reassurance, and helps maintain coat condition. However, over-grooming and hair plucking are associated with poor welfare states.
Social interactive play is often used as one indicator of good welfare. But this behaviour may not be visible in older animals. Keepers need to regularly and attentively observe primates' overall behaviour.
Aggression and primates
Primates should not display persistent signs of aggression, antisocial behaviour or long term conflict behaviour towards other animals or people.
Such behaviour includes physical aggression, physical or vocal threats, and aggression displays. Conflict is a natural part of the behaviour of many social animals. However, dominant (controlling) individuals should not dominate or bully other primates in the group. Individual animals may sometimes show aggression towards their keeper, but persistent undue aggression is a cause for concern.
Sporadic, acute aggressive behaviour is fairly common in some primate societies, but this is generally kept in check by learnt social skills. A thorough knowledge of species-typical behaviour is essential for interpretation of observed behaviour.
Persistent aggression and primates
Persistent aggression can develop when the size and structure of the environment does not allow animals to avoid and escape from one another. Individuals, deprived of the opportunity to learn the full range of social skills, may have problems with other animals socially, leading to aggressive interactions. Animals experiencing pain, or frustration, as a result of an inadequate environment, may become very aggressive.
Changes to group composition can lead to aggressive interactions, and so great care needs to be taken and advice sought to minimise these risks. Established compatible social groups should not generally be altered.
Aggressive interactions can also arise in mixed species environments, either because of species characteristics or individual behaviours. Problems with aggression should be tackled at the source, by correcting the causes. It is never acceptable to mitigate effects of aggression, for instance by removing canine teeth for the purposes of handling or husbandry, or extended separation/isolation from the group.
Resources for keeping primates
The following key resources should be considered when keeping primates:
- group composition
- changes to group composition
- enclosure size
- visual barriers
- access to resources
Primates should be able to express suitable defence and escape behaviours.
In their natural environment, primates that come into conflict can escape from one another to avoid physical and visual contact and disperse to other areas (for example, once sexual maturity is reached). They are also free to move away and escape from other stimuli or situations they find aversive.
The captive environment places certain restrictions on such strategies, which can lead to stress. It is important that adequate refuges and visual barriers are provided, including from people. Vertical space is particularly important, as escape responses tend to be upwards, and dominance relationships are often expressed, in part, by occupation of perches at different heights.
Self-grooming, feeding and drinking
Primates should display self-grooming, feeding and drinking behaviours relevant to the species concerned.
These maintenance behaviours are essential for primates’ physical well being and also provide stimulation.
Changes in maintenance behaviours can provide an early warning sign of a problem. For instance, reduced feeding or drinking can mean a problem before body weight or condition is affected. Over-drinking and over-eating can be indicative of a problem.
Self-grooming is a normal behaviour, but over-grooming (which has been linked to tension and anxiety) can result in hair loss and skin sores. Hair-plucking is a health concern, especially if the hair is swallowed and forms hair-balls in the digestive tract.
Primates should display physical activities relevant to the species concerned.
Tarsiers, some lemurs and bush-babies typically cling to and leap between perches, marmosets and tamarins cling to tree-trunks and gibbons swing from branch to branch. Performance of such natural activities is essential to both the physical and psychological health of primates, and it is important that they are provided with a wide variety of suitable facilities, that are the right size and spatial design to display these behaviours.
A change in activity levels, in both directions, can result in a welfare problem.
Sleeping and resting patterns and primates
Primates should display sleeping and resting patterns relevant to the species and individual concerned.
Primate species are generally nocturnal or diurnal. However, some species may be active at times by day and night, or most active at dawn and dusk. The environment and its management should take account of individual needs.
The way in which primates sleep and rest differs between species. For instance, some sleep together in groups in tree cavities, others may build nests. Furnishings and substrates to allow sleeping and resting behaviours should therefore be provided, relevant to the species.
An increase or decrease in the frequency of sleeping and resting behaviours show that there's a welfare problem.
Foraging and primates
Primates should display a wide range of foraging behaviours, relevant to the species. This encompasses exploration, search, capture, restraint (of prey items), manipulation, processing and consumption.
Primates spend a large part of their day foraging for food that may be widely dispersed or patchily distributed. In foraging, they use well-developed memory skills and the ability to solve complex problems, together with an advanced ability to use tools for acquiring food, for instance to extract kernels from hard nuts.
Foraging behaviours vary widely between species, and one species may employ a wide range of strategies. For instance, marmosets typically gouge holes in trees and eat the gum, but also forage for invertebrates among leaves. Keepers should make sure ample opportunities for their primates to do all such behaviours, in order to provide both mental and physical stimulation.
Access to food for primates
Primates should not show anxiety over access to food.
Care should be taken to prevent any individual animal becoming unduly dominant. All animals must have access to all components of the diet, and food should be dispersed sufficiently widely to make sure that normal social hierarchies do not result in anxiety in subordinate animals and prevent them from having access to food.
Parenting behaviours and primates
If allowed to breed, primates should express normal parenting behaviours for a suitable period of time that's relevant to the species concerned.
Primates have an extended period of maternal dependency, lasting well beyond nutritional dependency. Infants removed from their mother and natal group early, and as a result deprived of the opportunity to learn vital survival and social skills, are likely to develop behavioural and hormonal abnormalities, fail to integrate well with individuals of the same species, and are often unable to raise their own young successfully.
A poorly-designed and managed environment for breeding animals can cause stress, impair fertility, inhibit mating behaviour, and adversely affect care of the young, leading to infanticide, abandonment or stealing of young animals.
Activity and primates
Primates of all species display a wide repertoire of activities and behaviours. You should know the normal behaviour in captivity of the species you keep.
A restricted or restriction of the range of behaviours displayed can show that the environment is unsuitable for the animal’s needs, or that the animal is unwell. A general lack of or limited focus of, activity should be taken as a warning sign.
Scent-marking and primates
Scent-marking is a normal behaviour for many species. It plays a role in the development of social structures, social interaction, reproductive health, and in breeding behaviour. Cleaning regimes should be developed that do not adversely inhibit scent communication.
Too much repetition of normal behaviour should also be taken as a warning sign.
Effect of poor welfare
The common adverse welfare consequences of poor management include discomfort, boredom, fear, pain and stress, which, if unchecked, may lead to self-harm, and other abnormal behaviours, such as overt and persistent displays of submission, aggression or anxiety, be they physical or vocal. However, suitable enrichment can help reduce these behaviours.
A stimulating environment for primates
Primate groups need a relevant environment that is stimulating and gives individuals a sense of control and choice.
An inadequate environment may be associated with primates displaying abnormal behaviour. Pay attention to any changes in primates' behaviour including:
- abnormal repetitive behaviour (for example, pacing, rocking, self-clasping)
- self-harm - for example self-biting
- apathetic/depressed behaviour
- abnormal behaviour (for example, over-grooming, drinking urine and eating faeces)
Once primates develop abnormal behaviours as a result of poor welfare, these may persist throughout their lives. Everything possible should be done to prevent such behaviours developing, by providing a rich physical and social environment, and by being aware of, and looking for, early indications that the environment is not providing for the animals’ needs.
Signs of fear in primates
Signs of fear differ between species and include withdrawal, grimace, too much lip smacking, aggression and specific vocalisations.
Some primates may show instinctive fear of other species (for example, dogs, cats or snakes), and should be protected from the distress of being housed close to these creatures. The herding or predatory behaviour of a dog can easily cause distress to a caged primate.