Climate change and bird extinctions in the Amazon

since projections predict the incidence of high species richness within or around these areas (Fig 3). Additionally, when comparing the currently appropriate areas for species to occur with the dispersal and deforestation scenarios, it is possible to note the occurrence of areas that can act as climatic refuges for the species, especially in the regions known as “Mosaico do Gur- upi” and “Rio Capim” watershed (Area 1 and 2, Fig 3). Discussion Our results indicate that BAE’s endemic birds will lose an average of 73% of their suitable areas by 2050. Moreover, at least six of these 15 bird species will have either less than 10% or even no suitable areas for their occurrence in all scenarios we analyzed. Since they are highly dependent on forest habitats, these species are already undergoing strong reductions in their habitat because of the high rates of deforestation in the BAE [27]. Based on the parameters to define the threat status of a species [77,78], the projections per- formed in this study indicate a probable change in the threat status of our target taxa. Among these parameters, the extent of occurrence and area of occupation of the taxa of the Bele´m endemism center may considerably decrease by 2050 (Table 2, S1 Fig). Habitat loss is another factor that determines the threat status of the species [77], and a reduction of adequate habitat implies reduced species distribution and enhances its risk of extinction [79]. This factor mainly affects species such as C. f. pinima and P. obscura, both currently classified as critically endan-

gered (Table 1). Besides, our results support a general pattern of suitable area loss in both the mitigation and business-as-usual scenarios, which has also been found in several studies in recent years. The reduction of suitable habitat areas as a consequence of climate change has been reported not only for birds but also for a myriad of different organisms, such as mammals and plants [44,80,81]. Jetz et al. [82] evaluated the effect of climate change on birds worldwide and showed that the occurrence area of hundreds of species would reduce by 50%, and the most affected species would be those inhabiting in tropical regions. Anciães & Peterson [83], who studied the effect of climate change on 49 species of manakins (Pipridae), found that at least 20% of all species will be locally extinct from their current distribution, and species occur- ring in the Amazonian lowlands would be the most affected. Thus, the species of birds that would be most affected by climate change tend to be those that occur in tropical regions, espe- cially those that live in lowlands and have restricted spatial distribution, such as the birds that occur in BAE. Although climatic fluctuations in the tropical region are smaller compared to other regions [84], the high level of Amazonian species specialization may accelerate the consequences caused by changes in climate [85], which reduces their chances to adapt to such novel environ- mental circumstances [38,82,86]. Additionally, deforestation is determinant in habitat loss

[87], and becomes an aggravating factor for BAE’s taxa, as they are highly dependent on forest environments. These factors combined with anthropogenic activities, restricted distributions, and low dispersal ability, in virtue of species endemicity, can lead to severe population declines and, consequently, the loss of genetic variability [88], exposing the taxa to a higher risk of extinction. Assuming that a loss of suitable areas over 95% means a high risk of extinction [83], then at least 40% of our target species would be extinct by 2050 in any dispersion scenario (Table 2). The predicted loss of suitable areas for BAE’s endemic taxa can culminate in considerable losses of ecological services—e.g., seed dispersal—and maintaining the forest itself [89,90]. For instance, frugivores species such as P. b. bitorquatus, C. f. pinima e T. v. signata, which are endemic to BAE [91, 92, 93] and play a key role on dispersing seeds from this region, is pre- dicted to lose 44,57% of suitable habitat areas in future scenarios (Table 2, S1 Fig). Moreover, PLOS ONE Bird extinctions in the Amazon PLOS ONE | https://doi.org/10.1371/journal.pone.0236103 July 17, 2020 10 / 18