Lorisids must be carefully managed both in the wild and ex situ to ensure their continued survival. The Asian lorisines are rapidly diminishing in native habitats (Nekaris et al., 2010b), and while perodicticines are currently listed as Stable in the IUCN Red list of Threatened Species (IUCN, 2018), the lack of habitat will prove to be a threat to their long-term survival as African rainforests are being eroded (Pimley and Bearder, 2013). Most zoo and research populations are declining as well. Of all the lorisids, pygmy lorises (Nycticebus pygmaeus) currently have the best chance of attaining a self-sustaining ex-situ population. Although there are fewer than 50 pygmy lorises remaining in North America (Species360, 2018), an additional 150-plus animals are housed in facilities throughout Europe and Asia, thus enhancing opportunities for their ex-situ breeding management and genetic diversity.

Mammalian activity budgets are directly linked to an animal’s metabolism and energy requirements, which may change with the seasons and throughout an individual’s life span (Halle and Stenseth, 2000). Comparisons of activity patterns, including locomotor patterns under different ecological conditions, allow for exploration of ecological influences on animal behaviour and consequently in behavioural strategies (Onderdonk and Chapman, 2000; Warren and Crompton, 1998). Measures of group size, life history and activity budget, including locomotion and positional behaviour, are considered crucial for conservation management and hypothesis testing in behavioural ecology.

Lorises (family Lorisidae) are primates of the suborder Strepsirrhini. They belong to the infraorder Lorisiformes, together with their sister group, the Galagidae – galagos from sub-Saharan Africa. The systematics of the family Lorisidae have been long debated. Currently two subfamilies are recognised: Perodicticinae, including the two African genera Arctocebus (angwantibos) and Perodicticus (pottos), and Lorisinae, including the two Asian genera Loris (slender lorises) and Nycticebus (slow lorises) (Mittermeier et al., 2013; Rasmussen and Nekaris, 1998; Rowe and Myers, 2016) (1971) based on a series of craniodental features, and, more recently, supported by a cladistic analysis by Rasmussen and Nekaris (1998). Simpson (1967), however, identified several similarities between the two robust forms, Nycticebus and Perodicticus, and the two small-bodied, slender forms, Loris and Arctocebus. A cladistic analysis on craniodental data by Schwartz and Tattersall (1985) supported these two reciprocal monophyletic clades, but other morphological studies failed to identify a clade including both Perodicticus and Nycticebus (Masters and Brothers, 2002). To further complicate the taxonomy of this primate group, karyological studies conducted in the 1970s identified two alternative groups based on the number of chromosomes: Perodicticus and Loris share a diploid number of 2n = 62, while Arctocebus and Nycticebus exhibit a diploid number of 2n = 52 (although some populations of Nycticebus have 2n = 50) (de Boer, 1973; Masters et al., 2005).

The pygmy slow (hereafter pygmy) loris is endemic to Vietnam, Laos, southern China and eastern Cambodia (Brandon-Jones et al., 2004). The species is threatened by heavy exploitation for traditional medicine, pets (Nekaris et al., 2010b; Starr et al., 2010) and habitat loss (Streicher et al., 2008b). The first intensive field study of a wild population of pygmy loris occurred from 2008 to 2009 (Starr, 2011a; Starr and Nekaris, 2013; Starr et al., 2012a, 2012b), and only preliminary field surveys of wild populations had been conducted prior in Cambodia (Starr et al., 2011), Vietnam (Fitch-Snyder and Thanh, 2002; Tan, 1994) and Laos (Duckworth, 1994; Evans et al., 2000). Much of our knowledge of this species and decision-making about their conservation had come from knowledge gained in zoos (e.g. Fisher et al., 2003b; Fitch-Snyder and Ehrlich, 2003; Fitch-Snyder and Jurke, 2003; Jurke et al., 1997, 1998), or captive animals from trade (Streicher, 2003, 2004; Streicher and Nadler, 2003).

Historical records of animal hunting by humans in Asia are at least 40,000 years old (Roberts et al., 2001). However, taking into account that the regional decline of many animal species has occurred over the past 50 years, it can be seen that this issue is still topical as animal hunting is currently the second most serious threat to wildlife (Corlett, 2007). While in ancient history humans hunted predominantly for the purpose of livelihood, present objectives of hunting have changed quite radically. The focus of hunting animals now is predominantly for sale as domestic ‘pets’, for traditional medicine purposes and for the sale of products made from them such as exotic leather products and other tourist curiosities (CITES, 2019). In Asia, hunting of animals for the purposes of magic and religion is also widespread (Shepherd et al., 2004). Hunting has become a major problem as a result of the high human population density and the major infrastructure developments that have made it easier to access not only forest areas (Nekaris et al., 2010b), but also distant urban markets with luxury products (often medicinal) (Corlett, 2007). The degree of utilisation of some plant and animal species is high, and the trade in them, along with the loss of natural habitat, damages their populations, which brings some species to the brink of extinction (CITES, 2019). Especially the illegal trade in wild animals and their products poses a big threat to species’ survival as this trade is estimated to be billions of dollars annually (Barber-Meyer, 2010; Wyler and Sheik, 2013).

The superfamily Lorisoidea comprises two families: the Galagidae (galagos or bushbabies) and the Lorisidae (lorises and pottos) (International Board of Zoological Nomenclature, 2002). The families share nocturnal, arboreal lifestyles; a diet of small animals, fruits, nectar and sometimes tree exudates; and a dispersed form of sociality. However, they differ markedly in their manner of moving within their habitats. Galagids and lorisids can be thought of as ‘leapers’ and ‘creepers’, respectively. Galagos are active hunters of insects. All extant galagid species have elongated tarsal bones that enable them to perform a degree of leaping, although some species are capable of more extensive leaps than others. The lorises and pottos, by contrast, have tarsal bones that appear to have been secondarily shortened, and twisted in the process (Gebo, 1989). Their femora and tibiae are also rotated along their longitudinal axes (Gebo, 2014). For much of the time, lorisids move slowly over short distances – although they are capable of unexpected bursts of speed, particularly when hunting or when threatened (Vosmaer, 1770). The first European author to describe a lorisid – or indeed any lorisoid primate – was Willem Bosman, a trader for the Dutch West India Company, who lived for 14 years (1688–1702) on the Guinea Coast in the region now called Ghana. Bosman was not a scientist but a merchant, and while his record of the West African potto (Perodicticus potto potto) does not meet the requirements of a scientific description, it captured attention. Bosman wrote that, although the local Africans referred to the animal as ‘potto’ (1705: 250). As if laziness were not enough to condemn them, pottos also had a reputation for drunkenness. Wilhelm Peters (1876), the curator of the Museum für Naturkunde in Berlin, quoted one of his collectors, Dr Rheinhold Buchholz, as recounting an African tale that pottos seek out palm wine, and drink so much from the gourds hanging from the trees that they fall into a deep sleep. Buchholz did not believe this story; his captive potto did not accept fresh palm wine.

Wildlife trade, defined as the sale or exchange of animals or plants by people, affects a wide variety of flora and fauna around the globe. The scale of this trade ranges from transactions of a single animal or plant to the commercial trade of wildlife in their billions. Rapidly expanding human populations, increased per capita wealth, improvements in infrastructure, increased access to forest and wilderness areas, increased internet penetration levels, changing consumer preferences for wild meat or exotic pets and improved hunting and trapping technologies have led to an increase in the numbers of animals affected by this trade. Investigations into the sale of wildlife can be approached from a biological, socioeconomic, legal or human health perspective (Karesh et al., 2005; Linder et al., 2013), but are most frequently done for conservation and sustainable use reasons (Smith et al., 2009). These investigations are vital if we are to ensure the sustainable use of natural resources. Without knowing the number of animals or plants removed from the wild for trade, we cannot know if the trade is causing species to be overharvested to the point of extinction.

Lorisidae is a group of strepsirrhines that comprises the Asian lorises, the African pottos (including angwantibos) and their closest fossil relatives. As a group, extant lorisids are not very speciose, with 15 species currently identified (10 species of loris and 5 of potto; see 2015). The biogeographic and phylogenetic contexts of the evolutionary origin of lorisids have long been a matter of debate, without any clear resolution (Pickford, 2012). The main reason why there are only slow improvements in this research area is because lorises are rare in the African and Asian fossil record. Only seven species have been named (Table 3.1), suggesting that either lorisids have been a poorly diverse group throughout their evolutionary history, or that there is a hidden lorisid diversity yet to be uncovered beneath the forests of continental Africa and South and South-east Asia.

There is a rich history of work on paramasticatory and masticatory adaptations underlying phenotypic diversity in the feeding apparatus of lorisiform primates (Dumont, 1997; Nash, 1986a; Ravosa et al., 2010; Vinyard, 2007; Vinyard et al., 2003, 2007; Williams et al., 2002). Related studies have addressed the ontogenetic underpinnings of size-related patterns of craniomandibular covariation in lorisids and galagids, which constitute the two extant families of lorisiforms (Ravosa, 1998, 2007; Ravosa et al., 2010). Despite longstanding interest in the unique circumorbital region of taxa such as the slender loris (Cartmill, 1972), less well known is the role of allometry on variation in the circumorbital form of lorisiform and lemuriform strepsirrhines (Ravosa et al., 2006).

Nocturnal animals are difficult to see and follow, especially in dense rainforest conditions. Nocturnal research is fraught with difficulties not encountered by individuals who study animals in the day, from the need for expensive equipment, constant access to power supplies to run lights and potential for increased encounters with dangerous wildlife. The main drawback of nocturnal fieldwork is that it is simply more difficult to find and continuously observe an animal at night. Through hard work and perseverance it is possible to obtain ecological data on lorises and pottos in the absence of radio tracking (e.g. Das et al., 2014; Nekaris, 2001; Pliosungnoen et al., 2010). Much more detail can be obtained, however, through capturing, measuring, collaring and monitoring nocturnal primates. The essential nature of radio tracking for the study of the behaviour and ecology of nocturnal primates has been recognised since the 1970s (e.g. Charles-Dominique, 1977a; Charles-Dominique and Bearder, 1979), and is by most researchers considered a must for thorough research (Sterling et al., 2000). Radio-tracking studies of lorises and pottos remain limited (2000; Millspaugh and Marzluff, 2001). In this chapter, we review the methods for trapping and collaring slow lorises and pottos, as well as provide a case study of the importance of red light for observing their behaviour in a humane and productive manner (see Box 24.1).

Animals living in seasonal environments experience regular changes in their climatic conditions. Ambient temperatures and humidity might vary considerably between the hot and cold season, leading to differences in food availability. During the cold season, when most energy is required for endogenous heat production, food availability is often at its lowest. Maintaining homeostasis is a necessity for endothermic animals to allow proper cell function, normal behaviour and reproduction (Martín, 2001). Among the endotherms, heterothermic animals switch between poikilothermic and homeothermic strategies to minimise their energy expenditures during times of low food or water availability, alterations in food quality or increased food competition (Blanco et al., 2018; Dausmann, 2014; Streicher et al., 2017; Vuarin and Henry, 2014).

In contrast to the visual, auditory or olfactory senses, the sense of touch (a form of mechanoreception) has been relatively neglected in primate studies. Over the last few decades, our understanding of the ecology of touch, or how an animal explores and exploits its environment using tactile cues (or tactile information), has improved in both primates and non-primate mammals. Touch can take many forms in mammals, including vibrissal (or whisker) touch, hand touch (especially in glabrous fingertips) and skin touch. Comparative studies exploring the relative sensitivities of touch (e.g. vibrissae/face, hands, feet) in primates and non-primate mammals are often challenging without extensive behavioural training (Bauer et al., 2012; Dehnhardt and Dücker, 1996; Dehnhardt and Kaminski, 1995) or complex anatomical studies (Marshall et al., 2014; Mattson and Marshall, 2016a, 2016b; Peterson et al., 1998). We have had success in using anatomical and skeletal proxies to investigate the ecology and evolution of vibrissal touch. Indeed, there are established ecological correlates between touch sensory-end organs, like number and movement, and skeletal landmarks linked with touch acuity (Muchlinski, 2010a; Muchlinski et al., 2018). It is also possible to connect vibrissa movement to differences in behaviour (Dehnhardt and Kaminski, 1995; Grant et al., 2018; Kemble and Lewis, 1982; Muchlinski, 2010b). We have even modelled the evolution of vibrissae, discussing our findings in the context of touch (Muchlinski et al., 2013, 2018). In this chapter, we examine the ecology of face touch (i.e. vibrissal touch) among the lorisids using the above-mentioned lines of evidence. We suggest that the sensory ecology of the lorisids may be more specialised and novel than we initially thought.