Threats to the red‐billed curassow 413
but natural populations now survive in ,20 remnant for- ests in Espírito Santo and Bahia, with reintroduced popu- lations in three forest patches in Minas Gerais and one in Rio de Janeiro (IBAMA, 2004; Alvarez & Develey, 2010; Bernardo & Locke, 2014). The Brazilian Atlantic Forest is a high priority region for
global biodiversity conservation(Myers et al., 2000).Reduced to 12.5%of its original area, it is highly fragmented, withmost remnants,50 ha and c. 1.5 km from the nearest forest patch (Ribeiro et al., 2009). Over 60%ofBrazil’s human population live in this region (Scarano & Ceotto, 2015), and wildlife species with poor dispersal capabilities and/or high exposure to human persecution struggle to persist in such conditions (Ribeiro et al., 2009; Scarano & Ceotto, 2015). Red-billed curassows favour tall forest but with moderate
tree girths, conditions found mostly in secondary forest tracts (Alves et al., 2017). Knowledge regarding such habitat require- ments is critical to improve management for the species in a fragmented landscape. Here, we examined the relative im- portance of habitat quality and hunting pressure on the persistence of red-billed curassows in 14 forest patches in the Brazilian Atlantic Forest. We predicted that the species would be more persistent in forest patches surrounded by landscapes with higher habitat quality, which we defined as areas with (1) higher availability of water resources (river length), (2) higher proximity of rivers and other forest patches and (3) higher density of forest patches within the fragmented landscape (higher proportion of native forest cover).We also predicted that curassowswould persist better in forest patches in landscapes with lower hunting pressure, as reflected by (1) lower proportion of shaded cacao agroforest and farm- land (crops and livestock; the region’stwo main land uses), (2) fewer settlements, (3) lower incidence of unpaved roads and (4) greater distance from unpaved roads and settlements.
Study area
We conducted the study in 14 protected and non-protected forest patches of varying size (275–24,084 ha; Table 1) within the geographical range of the red-billed curassow in south- ern Bahia, Brazil (Fig. 1, Supplementary Tables 1 & 2). We selected these forest patches because they were identified as holding, potentially holding or having held populations of curassows, including locations mentioned in the species action plan (IBAMA, 2004), locations where curassowswere recorded by CSSB or locations of which CSSB had been no- tified informally by researchers. The forest patches are sur- rounded mostly by farmland (crops and livestock) but also eucalyptus monoculture, open ground, urban areas, sand- bank vegetation and/or mangroves (Landau et al., 2003). Except for sites 8 and 10 (Table 1, Fig. 1), protected and un- protected sites employ guards who offer a degree of safe- guarding against hunting and habitat loss.
Methods
Diversity of data sources We adopted a pragmatic approach to data collection be- cause of the urgent need to better understand the threats to the red-billed curassow, the logistic difficulties of field- work across the species’ range, and low encounter rates. Ideally we would have gathered data using a single method (e.g. line transects or camera traps) across all survey sites, but for reasons of practicality (e.g. hunter hostility to camera traps in some parts of Bahia) we needed to collate data from a diversity of qualitatively different methods to gather suffi- cient material in the short time frame available.
Data collection
We compiled information on each forest patch from the lit- erature and interviews, to determine the curassow’s status (i.e. persistence level). This was based on the number of re- cords in a 1-year period derived from (1) line-transect sur- veys, (2) camera-trap studies, or (3) interviews (Table 1). The time frame for the 1-year period was any year after 2007 when camera-trap and line-transect data were avail- able for the species. We categorized a population as per- sistent when one of these sources (sightings, photographs or interviews) yielded $3 records of curassows within a 1-year period (score 3,n = 4 forest patches), precarious if there were 1–2 records (score 2,n = 5 forest patches), or ex- tirpated (score 1,n = 5 forest patches) if curassows had only been sighted prior to 2007 (Table 1, Fig. 2). We used the persistence scores (3, 2, 1) in an ordinal lo-
gistic regression in which the response variable obeys an ordinal rank order (such as high, medium, low), because the use of binary data (records present/absent) and multiple logistic regression would oversimplify the analysis. The few data available from line transects, camera traps and inter- views allowed us to classify the response variable (persis- tence level) into distinct categories and adopt a statistical approach based on the ordinal response variable (see Data analysis). After obtaining permission (licenses in protected areas
and verbal permission for private lands), we conducted in- terviews to confirm the red-billed curassow’s presence, and estimated encounter rates using line transects in six forest patches and camera traps in four of these patches (Table 1). Interviewees, identified by researchers, landowners and/
or park staff as familiar with the local fauna, included pro- tected area rangers and managers, local people and/or re- searchers. To ensure that responses were independent, we did not interview members of the same family and con- ducted interviews with one person at a time (Canale et al., 2012). To confirmtheir familiarity with the red-billed curas- sow, we asked interviewees to identify the species in colour
Oryx, 2021, 55(3), 412–420 © The Author(s), 2020. Published by Cambridge University Press on behalf of Fauna & Flora International doi:10.1017/S0030605319000711
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