The titi monkey in fragmented landscapes 917


FIG. 1 Hypothesized influence of patch area, quality and visibility, and landscape connectivity, on the occurrence of the arboreal black-handed titi monkey Callicebus melanochir in a fragmented Atlantic Forest landscape (Fig. 2): (a) relative contribution of univariate (black bars) and compound models (black, patch area contribution; white, additive variable contribution) in explaining species’ occurrence; (b) expected response of the species occurrence to predictor variables in univariate models; (c) expected response of species occurrence synthesized for the three compound models having patch area and an additive variable.


(Cassano et al., 2012; Gestich et al., 2019), especially in small forest fragments. Such information is fundamental for facilitating conser-


vation actions beyond the creation of protected areas and for understanding how forest degradation affects arboreal mammals in fragmented landscapes, a relationship little studied (Mortelliti et al., 2010). For mammals that depend on high quality forests, the availability of well conserved habitats may be critical (Henle et al., 2004). Here we investigate the influence of patch and landscape


structure on the occurrence of the coastal black-handed titi monkey Callicebus melanochir in the Atlantic Forest hotspot (sensu Myers et al., 2000), using this species as a model for arboreal mammals inhabiting fragmented land- scapes in tropical forest hotspots. Neotropical primates are strictly forest-dependent (Cowlishaw& Dunbar, 2000), dir- ectly and negatively affected by deforestation (Estrada et al., 2017), and thus are appropriate models to study the impacts of forest reduction and fragmentation on the occurrence of forest-dependent mammals. We hypothesize that (1) patch area, quality and visibility,


and landscape connectivity, affect the probability of occur- rence of our model species, with patch area having the stron- gest influence (Fig. 1a); (2) all four patch–landscape metrics positively influence the probability of the species’ occur- rence (Fig. 1b); and (3) compound models (patch area plus each of the other metrics) will significantly increase model weights (Fig. 1c). Based on our findings, we discuss the usefulness of patch–landscape metrics in predicting the occurrence of titi monkeys and potentially other arboreal mammals in tropical forest hotspots and the application of such metrics for science-based conservation action.


Study area


This study was conducted in fragmented landscapes of the Atlantic Forest hotspot, southern Bahia State, Brazil (Fig. 2). The study area encompasses semi-deciduous forests


in a transition zone between coastalwet forests and inland de- ciduous forests within the Atlantic Forest domain (Thomas, 2003). Anthropogenic land-use conversion since the 1970s has transformed the originally continuous wet forests of the interior of southern Bahia into small fragments embedded in a matrix of pastures for cattle ranching (Coimbra-Filho &Câmara, 1996;Landau, 2003). The study area is therefore similar to other landscapes in the Atlantic Forest (Landau, 2003; Ribeiro et al., 2009) and other tropical forest hotspots (Turner&Corlett, 1996) regarding past processes and current patterns of forest loss and fragmentation.


Methods


Model species The coastal black-handed titi monkey Callicebus melanochir (Plate 1) is endemic to the Atlantic Forest of north-east Brazil (Culot et al., 2019). It is an arbor- eal species that occasionally moves on the ground and can disperse over short distances in non-forested areas (Mason, 1986; Souza-Alves et al., 2019), lives in groups comprising a monogamous pair and offspring, and occupies home ranges of 22–24 ha (Müller, 1995; Heiduck, 2002). The species is ca- tegorized on the IUCN Red List as Vulnerable to extinction as a result of habitat loss and fragmentation (Veiga et al., 2008) but the response of individuals to such habitat mod- ifications has not been studied.


Field surveys During March 2013–December 2014 (72 field days) surveys of the titi monkey were carried out in 38 frag- ments using playback censuses and interviews (following Jerusalinsky et al., 2006; Printes et al., 2011). The fragments studied were randomly selected to ensure complete coverage of the variation in the area of fragments. For playback cen- suses, recordings of the long-calls of C. melanochir were played along pre-existing trails and forest edges using a mini amplifier connected to an MP3 player (Jerusalinsky et al., 2006; Printes et al., 2011). We successfully used


Oryx, 2021, 55(6), 916–923 © The Author(s), 2021. Published by Cambridge University Press on behalf of Fauna & Flora International doi:10.1017/S0030605319001522


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