Using population surveys and models 847 This could be the case formammals currently categorized


as Least Concern and occurring in South America, where there is considerable concern for the conservation of habi- tats and species in the near future. For example, the lesser anteater Tamandua tetradactyla could lose .76% of its habitat by 2050 in Bolivia because of climate and land- cover changes (Osipova & Sangermano, 2016). Such a rate of habitat reduction fulfils the criteria for a categorization as Endangered on the IUCN Red List, but this species is cur- rently categorized as Least Concern (Miranda et al., 2014). The situation could be similar for other Least Concern xenarthrans (anteaters, sloths and armadillos) in South America, which are facing threats related not only to changes to their habitats but also to hunting, collision with vehicles, diseases and other anthropogenic factors that could cause large population decreases (Superina & Abba, 2020). Several Amazonian primate species occurring in the Arc


of Deforestation (a deforestation hotspot in south-eastern Amazonia) could potentially decline in the near future as a result of habitat loss (Silva et al., 2018, 2020; Sales et al., 2019; Rabelo et al., 2020). For example, current rates of de- forestation in southern Amazonia are predicted to reduce the habitat of the marmoset Mico chrysoleucos by 38–54% over 18 years (three marmoset generations; Silva et al., 2018). Although c. 20% of its range is safeguarded by pro- tected areas and Indigenous land designations (Silva et al., 2018), these rates of habitat loss are warning signs for the conservation of M. chrysoleucos considering the threats to the Amazon rainforest under the current government ad- ministration in Brazil. Unfortunately, however, this infor- mation was not included in the current IUCN Red List assessment and the species is still categorized as Least Concern (Röhe & Mittermeier, 2021). A similar situation could exist for Amazonian titi mon-


keys (Cheracebus and Plecturocebus; sensu Byrne et al., 2016), for which there is little information regarding threats, distribution or populations. Of the 31 species of Amazonian titi monkeys assessed for the IUCN Red List, 19 (61%) are categorized as Least Concern, with the justification that they have relatively large ranges, occur in protected areas and/or because there is no evidence of threats to their populations. Titimonkeys aremostly frugivorous, occur in a variety of for- est types (which include primary and secondary forests) and are considered tolerant of forest disturbance (Michalski & Peres, 2005; Bicca-Marques & Heymann, 2013). Nevertheless, at least seven Plecturocebus species occur in the Arc of Deforestation (Malhi et al., 2008), indicating they could potentially be threatened, and also unprotected. Extensions of the known range of Amazonian titi mon-


keys have been reported in Brazil (Monção et al., 2008; Quintino & Bicca-Marques, 2013; Printes et al., 2018; Rocha et al., 2019), Bolívia (Martinez & Wallace, 2021) and Peru (Vermeer et al., 2011), with new reports of sym- patry (Printes et al., 2018; Rocha et al., 2019) showing that


PLATE 1 Prince Bernhard’s titi monkey Plecturocebus bernhardi. Photo: Marcelo Santana.


the geographical distribution of Amazonian titi monkeys is more complex than was previously thought. Prince Bernhard’s titi monkey Plecturocebus bernhardi (Plate 1)is one such example. The range of the specieswas believed to be limited to thewest by the Ji-Paraná River but new records on thewest bank of this river indicate the distribution of this spe- cies is greater than previously thought (van Roosmalen et al., 2002;Monçãoet al., 2008; Quintino & Bicca-Marques, 2013, Silva-Diogo et al., 2018). Plecturocebus bernhardi is categorized as Least Concern because of its relatively large range and lack of evident threats that would result in population decline (Röhe & Boubli, 2018). However, data regarding the popula- tion of this species and the threats it faces are lacking. Here we present new occurrence data and the first population survey of P. bernhardi. We use predictive spatial modelling to estimate the extent of loss of its habitat and population under two future scenarios of land use (a more conservative governance scenario and a more realistic business-as-usual scenario) to reassess the conservation status of the species. This is the first study to reassess the conservation status of an Amazonian titi monkey by gathering new population data and using remote sensing information to model current and future habitat loss.


Oryx, 2022, 56(6), 846–853 © The Author(s), 2022. Published by Cambridge University Press on behalf of Fauna & Flora International doi:10.1017/S0030605322000655


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