This comprehensive overview of the behavioural and ecological diversity of the colobines shows that we have greatly expanded our understanding of the taxonomy, phylogeny, morphology, natural history, behaviour and conservation status of this subfamily since Glyn Davies and John Oates (1994) published the first book on them. Nonetheless, there remain many gaps in our knowledge. In Chapter 2, Roos highlights that our current understanding of the taxonomy of colobines should be considered preliminary because classifications are still largely based on phenotypic differences between museum specimens. Changes will likely need to be implemented as data become available on ecology, behaviour, morphology and especially genetics of many species and subspecies. Roos also notes that relative to the cercopithecines, colobines are neglected in study effort and thus new findings have the potential to expand our understanding of their taxonomic diversity, especially in genera such as Piliocolobus, Colobus, Presbytis, Trachypithecus and Semnopithecus that are found over large geographic areas and are species-rich.

Colobines display an array of different types of social organization. In some Asian colobines (most prominently the snub-nosed monkeys, Rhinopithecus spp.) and one subspecies of African colobine, social organization is multilevel, i.e. social units are characterized by a complete absence of exclusive territories, occupy wholly shared ranges and are nested within a larger, bounded social matrix. This chapter reviews and discusses the composition and social dynamics of colobine multilevel societies as well as the causes and consequences of living in such a complex social setting.

Colobinae, which includes more than 70 species grouped into 10 genera distributed throughout Asia and Africa, show a wide range of ecological and social traits. The colobines are generally forest-living and arboreal, which can make research on this often-elusive group difficult. Despite these challenges, our understanding of colobine behaviour, ecology and morphology has increased a great deal over the decades since the first research review on this primate subfamily was published by Davies and Oates (1994). While new research has demonstrated the incredible variation of colobine natural history, and the adaptability of this group, some colobine populations have declined and are now critically endangered. The Colobines brings together experts from around the world in an innovative volume that summarizes the current knowledge on colobine populations.

The odd-nosed monkeys represent a monophyletic group of phenotypically unique primates. They include five species of snub-nosed monkeys (Rhinopithecus), three species of doucs (Pygathrix) as well as simakobu (Simias concolor) and the proboscis monkey (Nasalis larvatus). These species are ecologically diverse and inhabit a gradient of environments in China and southeast Asia, from wet equatorial forests to alpine forests. Odd-nosed monkeys tend to be shy and difficult to habituate, and often range over relatively large areas. Many are also renowned for inhabiting remote areas with rugged terrain and inclement climatic conditions. It is thus not surprising that, until fairly recently, they were among the least studied and most enigmatic extant diurnal primates. However, since the beginning of the new millennium, an expanse of new and exciting research has been conducted on these colobines. In this chapter, we provide an overview of the current knowledge of the ecology and behaviour of odd-nosed monkeys and analyse some of their key behavioural traits and ecological adaptations in light of what is known about other colobines and primates as a whole.