800 R. Freire Filho and J. M. Palmeirim
(Carmignotto et al., 2012), but could have been introduced by people long ago (monkeys are often kept as pets by Indigenous People, so this population could potentially have originated from escaped animals). The eastern limit of the range of A. ululata is clear,
defined by the high-aridity conditions in central Ceará. However, the western limit is ill defined and possibly explained by the wet conditions prevailing in Maranhão. Moreover, competition with Alouatta belzebul, a closely re- lated species occurring further west, may contribute to shap- ing the western limit of the range of A. ululata. It is unclear if the two taxa are distinct species or differentiated popula- tions of the same species (Viana et al., 2015). The variables used in the Maxent model are coherent
with the biology of the species (Oliveira & Kierulff, 2008). Per cent tree cover was the most important of these variables and suitability was low up to c. 50% tree cover, which is probably explained by the marked arboreal habit of the species (Oliveira&Kierulff, 2008). The species’ diet of leaves and fruit may also contribute to its dependence on dense tree cover, as trees are its main food source (Oliveira & Kierulff, 2008). Moreover, the results indicate that A. ululata prefers tall forest, even though it occupies a variety of wood- land types (Oliveira & Kierulff, 2008). The second and third most influential variables in the
model are both climatic and related: aridity index and pre- cipitation in the driest quarter (Bio17). The results indicate that regions with an extreme dry season are unsuitable for A. ululata, suggesting vulnerability to the ongoing aridifica- tion of the Caatinga (Torres et al., 2017), where it is predicted that by the end of the 21st century temperatures may be up to 3.5–4.5 °C higher and rainfall 40–50% lower than at present (PBMC, 2013).
Priority areas for conservation and current level of conservation
The priority areas identified using Zonation (Fig. 5a) should combine high habitat suitability, identified by Maxent, with good connectivity and low conservation constraints. This should make our results a good basis for conservation plan- ning. However, both Maxent and Zonation modelling are affected by sources of error, such as inaccuracies in species occurrences and environmental layers, which create uncer- tainty (Graham et al., 2008;Moilanen et al., 2017). New and better models should be generated as more information on species or better environmental layers become available, and management decisions may have to be adjusted to take the new results into account. However, the inevitable uncer- tainty associated with models should not be an obstacle to their careful use in planning conservation action; in the face of rapid environmental change the risks of inaction are probably greater than those of using models judiciously (Wiens et al., 2009).
The priority areas identified encompass ecologically dis-
tinct regions. For example, the A. ululata population that in- habits the mangroves at the mouth of the Parnaíba River has a unique ecology (e.g. a diet composed of mangrove plants). The groups that inhabit the enclave region of Ceará live mostly in humid areas with open ombrophilous forest. Adaptations to these different environments may have re- sulted in populations of A. ululata with distinct behaviours, ecologies, gene pools and even morphologies. It is desirable to protect the various ecological contexts in which the spe- cies is present. Virtually all priority areas with protected sta- tus are in the northern part of the species’ range. The south, including the region with most occurrences, is unprotected. This situation reflects the scarcity of protected areas in the Caatinga (de Marques&Peres, 2015;DRYFLORet al., 2016). The level of conservation provided by most protected
areas in the range of A. ululata is minimal. Of the nine rele- vant protected areas only two (Ubajara and Sete Cidades National Parks) are fully protected, with nature preservation being their main objective, and only indirect use of natural resources allowed (MMA, 2016). All other conservation units allow sustainable use of natural resources (MMA, 2016), which needs to be well managed to avoid damage. However, management is insufficient because of a lack of human and financial resources. Moreover, in this region awareness of the protected areas is low (Drummond et al., 2009). Our analysis indicated that deforestation is ongoing throughout most of the priority areas, even within protected areas (Fig. 5b), in line with the general trend of tree cover loss in the Caatinga (Beuchle et al., 2015). The situation is better only in federally protected National Parks, where we did not identify recent deforestation. Thus it is evident that protected areas currently make only a small contribu- tion to the protection of A. ululata and the other natural values of the Caatinga.
Implications for conservation
TheMaxent analysis indicates that good tree cover and levels of aridity lower than those prevailing in the Caatinga region are critical for A. ululata, suggesting that the species is affected by both deforestation and climate change.Unfortunately, tree cover is declining (Beuchle et al., 2015), even in protected areas (Fig. 5c), and arid conditions are increasing (Torres et al., 2017). This negative context should be taken into consideration in planning the conservation of the species. Based on the results of our spatial analyses we recom-
mend four conservation actions for A. ululata. These actions vary across the range of the species (Fig. 5c). Firstly, Maxent modelling indicates that the range of A.
ululata includes poorly surveyed areas where the presence of the species has not been confirmed, and the Zonation ana- lysis indicates that some of these areas have a high level of
Oryx, 2020, 54(6), 794–802 © 2019 Fauna & Flora International doi:10.1017/S0030605318001084
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