Ways to reduce stereotypies of primates housed in zoo exhibits
Bradley Ward (Word count = 1099)
Introduction
Stereotypies are defined as repetitive, unvarying movements that appear to serve no obvious function and have so far only been observed in captive animals and humans (Broom, 1983; Mostard, 2011). The current understanding of the causes of stereotypies are summed up by Mason and Rushen (2008) as; captive environments continually triggering specific behavioural responses; environments creating sustained stress, affecting specific brain regions and so how they sequence behaviour; and altered C.N.S. development due to their early rearing environment. These conditions then cause the development of pacing, body-rocking, and oral stereotypies, such as sham-chewing, to develop in primates and have been found to be endemic among zoo populations, despite enrichment efforts, with no studies completely abolishing them (Mason et al., 2007; Birkett and Newton-Fisher, 2011). The reduction of these stereotypies is therefore important in zoos in order to improve captive welfare, which is linked to decreased stereotypies, as well as improve the experience of visitors which may view stereotypic animals in a negative light (Mason and Latham, 2004; Broom, 1991; Marriner and Drickamer, 1994). Primates where specifically chosen for this paper due to the large amount of stereotypic research done on them in regards to environmental enrichment, pharmacological treatment, and positive reinforcement training, which will all be talked about. Other stereotypic treatments such as breeding programmes to reduce genetic predispositions are not talked about due to the lack of literature on non-human primates, but can be read about in a number of other papers in regards to voles (Schoenecker and Heller, 2000), parrots (Garner et al., 2006), and mink (Jeppesen et al., 2004).
Enclosure and Environment Enrichment
One of the best and most immediate ways to reduce stereotypies in primates is to improve the enclosure that the animal is staying in, with size, complexity, public exposure and social isolation all important factors. Enclosures that are too small have been shown to increase stereotyped behaviour due to spatial restrictions in a number of primate species, with height of the enclosure shown to be most important (Draper and Bernstein, 1963; Paulk et al., 1977; Prescott and Buchanan-Smith, 2004; Kitchen and Martin, 1996; Buchanan-Smith et al., 2004). Although this is one of the simplest ways to reduce stereotypies, it is often quite expensive for zoos to build bigger enclosures, and so enriching existing enclosures may be preferred. Enrichment can be hugely useful in reducing stereotypies with foraging material such as plants, destructible objects such as phone books, and food puzzles all showing beneficial effects in all primate species (Bryant et al., 1988; Wormell and Brayshaw, 2000; Dickie, 1998). As well as this, group housing has helped to further reduce the occurrence of stereotypies in primates, especially in infants that are raised with their mothers among these groups; with mirrors or viewing windows helping to reduce stereotypies in individuals that must be housed separately (Bellanca and Crockett, 2002; John et al., 2012; Brüne et al., 2006; Spijkerman et al., 1994). On top of the internal enclosure factors, external factors such as visitors can also influence primates in a variety of ways with some studies suggesting positive effects (Choo et al., 2011; Davis et al., 2005) and many suggesting negative effects (Wells, 2005; Birke, 2002; Mallapur et al., 2005; Hosey, 2000). Although their does seem to be some differing opinions in the literature, the overall consensus is that large groups of people increase stress levels which can cause stereotypies to manifest overtime (Cabib, 2006), ways to mitigate this may be to create smaller viewing areas and spread them out around the enclosures, or allow the primates an area to relax away from an
