chapter 28 Causes and consequences of coati sociality Ben T. Hirsch and Matthew E. Gompper Ring-tailed coatis (Nasua nasua) © B. Hirsch Introduction of Kaufmann’s work, and similar studies on pri- mates and other carnivores, have greatly enhanced Over fifty years ago John Kaufmann conducted a our understanding of how and why animals live in two-year study on the white-nosed coati (Nasua groups. Such issues frame the core of the modern narica) on Barro Colorado Island, Panama. The field of behavioural ecology. resulting monograph (Kaufmann 1962) is a solid Animals live in groups when the benefits (e.g. examination of the natural history of the species, a greater ability to survive threats from predators with an emphasis on understanding its social struc- and pathogens) are greater than the costs (e.g. in- ture. Although many such studies now exist, Kauf- creased competition for resources such as food or mann’s study bordered on revolutionary at the time mates) (Krause and Ruxton 2002). Overlaying such because this was one of the first studies to gather cost–benefit ratios are the genetic relatedness of in- detailed ethological data of wild vertebrates via dividuals and the willingness of animals to coop- habituation of free-living social animals. The idea erate in a manner that increases the benefits and of following animals from a distance of just a few decreases the costs of sociality. Among the mus- metres, and observing the nuances of their behav- teloid carnivores, studies of coatis have contrib- iour, was relatively novel at the time. The results uted more to our understanding of the causes and Hirsch, B. T. and Gompper, M. E., Causes and consequences of coati sociality. In: Biology and Conservation of Musteloids. Edited by David W. Macdonald, Christopher Newman, and Lauren A. Harrington: Oxford University Press (2017). © Oxford University Press. DOI 10.1093/oso/9780198759805.003.0028 28-Macdonald-Chap28.indd 551 31/05/17 8:32 PM 552 BIOLOGY AND CONSERVATION OF MUSTELOIDS consequences of group-living in the sub-order than Distribution, phylogeny and conservation any other species, with the possible exception of the European badger (Meles meles). Indeed, among To better understand the determinants of social- the smaller members of the order Carnivora, stud- ity in coati species, it is important to note that this ies of coatis (along with those of badgers, da Silva group is composed of several species that differ in et al. 1993; Woodroffe and Macdonald 1993; John- their ecology and behaviour. Coatis comprise two son et al. 2001; dwarf mongooses [Helogale parvula], genera: Nasua and Nasuella. All species in both Creel and Creel 1991; Creel and Waser 1994; Cant genera are believed to be highly social, although et al. 2013; and meerkats [Suricata suricatta], detailed field studies of social structure have only Clutton-Brock et al. 1999, 2001, 2008) provide the been conducted on white-nosed and ring-tailed co- core of our understanding of how and why indi- atis. Nasua species occupy diverse habitats from the viduals live in groups. Furthermore, because not all south-western United States to Northern Argentina individual coatis are social, coatis are an ideal study (see Macdonald et al., Chapter 1, this volume). The system to study why an individual animal might white-nosed coati is found in Central and North choose a group-living or solitary lifestyle. America, and at its northern extreme, the arid Chir- Against this backdrop of costs and benefits of icahua and Huachuca Mountains of Arizona and group-living, we examine coati social structure based New Mexico in the United States. The species is on insights gained from a series of multi-year studies found throughout mainland Mexico and Central conducted on N. narica and N. nasua (the ring-tailed America, except the Baja Peninsula. The southern coati). We draw principally from our work in Pan- geographic range limits of the white-nosed coati are ama and Argentina, but also discuss insights gained unclear; the species occurs throughout Panama and from work conducted in the United States, Mexico, may also occur in parts of Colombia and Ecuador. Guatemala, Costa Rica, and Brazil (Table 28.1). Whether the species is sympatric in these regions with the ring-tailed coati, and how the two species interact if sympatric, has yet to be examined. The Table 28.1 Multi-year studies of white-nosed (Nasua narica) and ring-tailed coati is found throughout much of South ring-tailed (N. nasua) coatis. America, reaching the southern limits of its range in northern Argentina and Uruguay (Gompper 1995; Species Locale Habitat References Gompper and Decker 1998). N. narica Barro Colorado Seasonal tropical Gompper 1994, A third species of Nasua, the dwarf coati, N. Island, Panama forest 1996; Gompper nelsoni, is endemic to low-lying Cozumel Island, et al. 1997a, 1998 Mexico. The dwarf coati is closely related to the N. narica Barro Colorado Seasonal tropical Russell 1979, white-nosed coati, but is morphologically distinct Island, Panama forest 1981, 1982 and has been isolated on Cozumel Island for sev- N. narica Barro Colorado Seasonal tropical Kaufmann 1962 eral thousand years. The appropriate taxonomic Island, Panama forest status of the dwarf coati is unclear (Decker 1991; N. narica Jalisco, Mexico Subtropical dry Valenzuela 1998; McFadden et al. 2008, 2010). Applying species-level forest Valenzuela and Macdonald recognition would lead to the dwarf coati being one 2002 of the rarest of small carnivore species, deserving im- N. narica Arizona, USA Dry forest Hass 2002b; Hass mediate conservation attention (Cuarón et al. 2004). and Roback 2000 Alternatively, if the dwarf coati is merely attributed N. narica Tikal, Guatamala Tropical forest Binczik2006; status as a subspecies of the white-nosed coati (that Booth-Binczik2001 is, N. narica nelsoni), conservation concerns are less- N. nasua Iguazú, Argentina Subtropical Hirsch 2007a, b, ened, as well as concerns about mainland white- Atlantic forest 2009, 2011a, b nosed coatis released on Cozumel hybridizing with N. nasua Pantanal, Brazil Seasonal Olifiers 2010; dwarf coatis. floodplain Bianchi 2009; The mountain coatis, which comprise the ge- Bianchi et al. 2014 nus Nasuella, occur in the cloud forests and alpine 28-Macdonald-Chap28.indd 552 31/05/17 8:32 PM CAUSES AND CONSEQUENCES OF COATI SOCIALITY 553 tundra (páramo) of the Andes of Venezuela, Colom- The two mainland species of Nasua are widely bia, Ecuador, and perhaps Peru (Balaguera-Reina distributed and have been found at high population et al. 2009; Helgen et al. 2009). The distributions of densities in some locations (e.g. >50 individuals per the mountain coati species are poorly known. Tra- km2, Wright et al. 1994). For the most part, conser- ditionally, a single Nasuella species was recognized: vation concerns focus on particular populations N. olivacea. Recently, however, detailed morpho- or discrete locales. While overhunting and habitat logic and molecular examinations of the genus by destruction have resulted in declining or extirpated Helgen et al. (2009) have resulted in the recogni- coati populations in some areas, there is little evi- tion of two distinct taxa: the eastern mountain coati dence for large-scale declines in coati populations (N. meridensis), which is endemic to the Venezuelan across Central and South America. In contrast, Andes, and the western mountain coati (N. olivacea) the dwarf coati is listed as a threatened species in endemic to the Andes of Colombia and Ecuador Mexico (SEMARNAT 2002) and Cuarón et al. (2004) (see Macdonald et al., Chapter 1, this volume). argue the taxon should be designated Critically En- At higher taxonomic levels, molecular analyses dangered by the IUCN based on small and rapidly indicate that coatis are most closely related to ol- declining population size, and small geographic ingos (genus Bassaricyon), with the split between range. The conservation status of the mountain the two genera occurring in the Miocene (Koepfli coati species is also of concern. The combined im- et al. 2007). Understanding of intra-Nasua evolu- pacts of habitat loss, hunting, and climate change tionary relationships is more preliminary. While are likely to have a negative influence on the local fossil Nasua are first recorded from Late Pleisto- and regional persistence of these high-elevation cene South American deposits (Berta et al. 1978), species (Helgen et al. 2009), and Balaguera-Reina molecular estimates of divergence times of white- et al. (2009) propose that a Near Threatened IUCN nosed and ring-tailed coatis indicate a split at 7–8 status is justified. mya, well before the Great American Interchange (GAI) that occurred with the rise of the Isthmus of Panama about 3.5 mya. The presence of North Linking social structure, morphology and South American sister taxa of Nasua may be a and feeding ecology function of pre-land bridge waif dispersal to South America prior to the GAI, followed by isolation Much of what is known about the biology and ecol- and differentiation prior to secondary contact af- ogy of coatis is based on Kaufmann’s initial study ter the rise of the Panamanian land bridge (Koepfli of white-nosed coatis on Barro Colorado Island, et al. 2007; Forasiepi et al. 2014). Helgen et al. (2009) Panama. One of the behavioural patterns that included several white-nosed and ring-tailed coatis Kaufmann documented on Barro Colorado was that in their molecular phylogeny of mountain coatis adult males and females differed in their degree of and observed that Nasuella was the sister lineage to sociality. In general, coati groups (or ‘bands’), are N. narica. This suggests that Nasua, as currently rec- composed of adult females and their offspring, while ognized, is not monophyletic, and Nasuella species larger adult male coatis are usually solitary outside of should be reclassified as Nasua species, resulting in the mating season.