Climate change and bird extinctions in the Amazon

reports from the Intergovernmental Panel on Climate Change (IPCC) have indicated an alarm- ing future as a consequence of these processes. As predicted, climate change brings with it transformations in global climate patterns, such as the melting of both glaciers and permafrost, as well as changes in precipitation regimes [5,6]. Altogether, these transformations threaten biodiversity and the resilience of natural ecosystems [7] by, for instance, decreasing the num- ber of suitable habitats, altering ecological interactions among species, thus, negatively impact- ing the ecosystem services [8,9,10,11,12,13]. The relationship between climate change and deforestation can aggravate their negative impacts on natural ecosystems [14]. The increase in global average temperatures and longer drought periods, together with habitat reduction and fragmentation, can expose species to an even more vulnerable situation [15]. Some climate change projections predict considerable impacts on species distribution and, consequently, loss of ecosystem functions [16,17]. More- over, the areas affected by the effects of climate change are under significant threat from anthropogenic activities that aggravate deforestation [18,19]. Given this climate change scenario and its implications for biodiversity, tropical rainforests are among the most impacted areas [20]. Several studies claim a possible “savannization” in eastern Amazon due to more prolonged drought periods in this region [21,22]. Such lengthier

drought periods have directly affected the diversity of the flora [4,23] and influenced the distri- butions of forest-dependent species [24]. Also, the Amazon forest has been affected by various anthropogenic activities, such as logging, large-scale mechanized agriculture, mining, larger livestock populations, and infrastructure expansion [25,26,27,28,29]. Although these activities affect several Amazon regions, the results of these impacts vary between its areas of endemism [30]. Areas of endemism delimited by large rivers are an essential biogeographic pattern in the Amazon. They form a mosaic with a complex evolutionary history [27,30], containing biotas and unique ecological processes, which are the result of several speciation events [31]. Five of the eight endemism centers from the Amazon proposed by Silva et al. [30] are located in the Amazonian region known as the “Deforestation Arc,” where 75% of all deforestation areas are concentrated [28,32,33]. Among these, the Bele´m Area of Endemism (BAE) is the most impacted, with approximately 76% of its total area already deforested [27]. Currently, BAE has a large concentration of endangered Amazonian bird species, of which 56% of the region’s endemic bird species are endangered [34,35]. Birds are considered key organisms for maintaining the ecological balance within a habitat mainly because of their seed dispersal capabilities [36] and control of insect populations [37]. They also serve as efficient bioindicators due to their sensitivity to environmental change [38]. Thus, they are excellent

models for understanding the effects of future climate change and for outlining both conserva- tion and maintenance strategies of biodiversity and ecosystem services. Species distribution models (SDMs) are commonly used tools that are efficacious in the assessment of the effects of climate change on biodiversity [39,40,41,42,43,44]. These models are based on Grinnell’s [45] niche concept, which describes the ecological niche as the distri- bution unit occupied by a species, where individuals are constrained by both physical and cli- matic variables. Thus, based on species occurrence data, and local climatic conditions, it is possible to define the species’ climatic tolerance and predict regions of potential climatic suit- ability to them [46]. SDMs are also used to identify climate refuge areas, which are habitats that maintain their climate patterns over time amid areas where the climate is altered [47]. In these areas, the species tend to have conserved niches, as they are not expected to adapt quickly to new climatic conditions [48,49]. Therefore, to identify these climate refuges is of paramount importance, as these areas have the necessary resources for the long-term maintenance of the species populations, even in the face of the foreseen climate changes [47,50,51,52,53]. Such assessments are fundamental, especially in landscapes undergoing fast modification [54] and PLOS ONE Bird extinctions in the Amazon PLOS ONE | https://doi.org/10.1371/journal.pone.0236103 July 17, 2020 2 / 18 #308403/2017-7) as a scholarship. There was no

external funding to support this research. Competing interests: The authors have declared that no competing interests exist.