It is vitally important to house species in appropriate group structures. For many species social living provides more benefits than simply finding food and avoiding predation, it is a major source of stimulation.
4. Inappropriate social groupings and isolation
It is vitally important to house species in appropriate group structures. For many species social living provides more benefits than simply finding food and avoiding predation, it is a major source of stimulation. The social environment of many species represents a constant source of complex mental stimulation, the complexity and variety of which we could never hope to replace by any form of environmental enrichment (Young, 2003).
Changing social groupings and dynamics, removing an animal for training, performance or transport can lead to periods of social isolation, or can bring animals into contact with new groups. Often individual animals are exchanged between circuses or lent to another circus for a season resulting in long term disruption of social groups.
Social species such as elephants are often kept in isolation, such is the case with Anne the elephant (the last remaining elephant in a UK circus), while animals that are solitary, such as tigers, are often kept in groups (Nevil & Friend, 2003).
4.1 Social Isolation and Separation from Companions
The detrimental effects of social deprivation and separation have been widely documented in many species and are known to cause behavioural and physiological indications of stress (Tarou et al., 2000).
- During a study of social separation in giraffes, a resident male was removed from his two female companions. The removal of the male resulted in the females showing protest behaviours, including increased activity, stereotypical behaviour, and increased contact behaviour with each other. They also showed decreased habitat utilisation. These results supported the findings of studies previously carried out in other species, particularly non-human primates, where the first change in behaviour is protest, characterised by increases in vocalisations, locomotion and stereotypical behaviour, as well an contact and clinging if the animal is housed with peers during the separation. Giraffes are not known to be highly social animals in the wild, yet their aversion to this kind of social separation proves that a complex social structure is not a prerequisite for social attachment (Tarou et al., 2000).
- Spectacled bears have been documented displaying stereotypic repetitive head-tossing behaviours as a result of social frustration when they were prevented from interacting with other bears that were in close proximity to them (Fischbacher & Schmid, 1999).
- In the wild elephants live in groups and display complex social behaviour. The natural grouping of both African and Asian elephants is of a family unit and the social bonds between the members of the family are very strong (Macdonald, 2004). Such family units are not possible in the circus environment where elephant groupings are varied and changeable. Supporting this, is a study on circus elephants where it was found that the limited opportunity for social contact was the principle causal factor in the female Asian elephant’s stereotypy (Kirkden & Broom, 2002).
- Piglets, when isolated from others, show increased frequency of sitting and decreased time spent active, increased frequency of escape attempts, decreased frequency of play and increased frequency of pawing behaviour and a lower degree of interest in novel objects; all of which changes are considered to reflect a negative impact on the piglets’ welfare (Herskin & Jensen, 2000).
- Social separation in cattle is known to induce struggling and large increases in vocalisation, heart rate and plasma cortisol concentrations. The mere presence of other cattle is sufficient to prevent struggling and vocalisation, regardless of peer identity, a finding that shows that a non-specific attachment can develop between individuals and their peers (Boissy & Le Neindre, 1997).
- 4.2 Forced Proximity with other Animals
- In the wild tigers are solitary animals, coming together only for mating. A study on circus tigers describes how circuses often transport tigers in groups and that severe fights can break out (Nevill & Friend, 2003). The paper describes how ‘major movement’ in the back of the truck could be felt by the driver in the cab indicating fighting. Whenever this happened, the method of stopping the fight was ‘sudden application of the brakes’ which would cause the fight to cease until the truck could be stopped to separate the tigers. This is clearly an unacceptable situation.
- Travelling circuses frequently put different species of large cats together and have even created a lion-tiger cross, calling it a “liger”. However putting these species together can cause serious aggression, as demonstrated by the attack by a male tiger on a lioness at Circus Harlequin, mentioned earlier.
- Studies of captive ungulate species have shown that increased social density may produce competition for resources, especially food, which could then increase the likelihood of stereotypic licking (Bashaw et al., 2001).
- 4.3 Inappropriate Groupings with other Species
- As well as suffering from the effects of isolation, animals also suffer when forced to live in close proximity to another species, as is often the case in circuses. The suffering is further increased when the other species is a natural predator or prey of the animal in question; as documented in ADI observations.
- When next to cattle or pigs, farmed red deer stayed as far as possible from them, and were generally more active, showed more agonistic interactions and had elevated plasma cortisol concentrations. Some of the deer had been previously familiarised with the presence of cattle but the results of the study showed that these more ‘experienced’ animals did not habituate to the experience of the unusual grouping and there was even evidence to suggest that previous exposure to cattle made red deer more aversive to them (Abeyesinghe et al., 1997).
- Like other ungulates, deer have evolved a naturally exaggerated flight distance as an adaptation for escape from predators and in a confinement situation where they are housed close to other species, they cannot prevent these other animals from entering their ‘flight zone’.
- Obviously ruminants and omnivores like pigs do not pose a predatory threat to deer, but they may pose other threats: Firstly, the fact that they are not familiar means that they will be perceived as a potential threat, secondly other animals may pose a threat or competition over resources and thirdly different species of animal have evolved specialised means of communicating with one another and the unpredictability of noise from another species and an inability to read each others signals may cause problems in mixed species groups (Abeyesinghe et al., 1997).
4.4 Close Proximity of Predator and Prey Species
Prey species show specific adaptations that allow recognition, avoidance and defence against predators (Apfelbach et al., 2005). However in the restrictions of a travelling circus environment, animals such as horses, other ungulates and smaller animals are frequently exposed to the presence of one or more predator species, such as dogs, tigers, lions, bears etc. Predator species may also become stressed and frustrated by the presence of prey species that they are unable to hunt, or of competitors which they cannot compete with.
- Studies on mammalian changes in behaviour when exposed to the presence of a predator, have shown responses such as, anxiety-like behaviour and long lasting neural circuit changes in the brain (Adamec et al., 2005).
- For many mammalian species an adaptation for predator avoidance is sensitivity towards predator-derived odours (Apfelbach, 2005). A recent review of the latest research on the effect of predator odours in mammalian prey species describes how pregnant female rodents exposed to predator odours may give birth to smaller litters and exposure to such odours in early life can hinder normal development (Apfelbach et al., 2005). This paper documents a long list of mammalian species where avoidance of predator odours has been studied and documented, including, rodents, possums and sheep.
- Behavioural effects shown in animals exposed to predator odours include, inhibition of activity, suppression of non-defensive behaviours such as foraging, feeding and grooming and shifts to habitats or secure locations where such odours are not present (Apfelbach et al., 2005).
- Even closely related animals such as different species of exotic cats can find the presence of the other species aversive. A zoo study investigating the low reproductive success rate of small exotic cats in captivity pointed out that most of these cats are solitary in nature, yet in captivity are routinely housed in pairs and managed in close proximity both to other species of small cats and larger cats which they may perceive as potential predators (Mellen, 1991) or competing for resources and territory. Cats mainly work to avoid contact with other cats and show abnormal and stress behaviours when their core territory is encroached upon. This was cited as one of the potential factors to explain the lack of breeding success with this species in captivity.