Every two years, the “Primates in Peril: The World’s 25 Most Endangered Primates” report is published by the International Union for Conservation of Nature’s Species Survival Commission Primate Specialist Group (IUCN SSC), in collaboration with the International Primatological Society, to raise global awareness of the most threatened primate species and help guide conservation priorities (Schwitzer et al. 2019; Acerbi et al. 2020; Reuter et al. 2021). This list – hereafter referred to as the Top 25 list – is defined participatively, by consensus, in a workshop, selecting among the species classified as Critically Endangered or Endangered in the IUCN Red List (IUCN 2024). Thus, it considers the criteria applied to the IUCN assessment, such as population size and trends, and the geographic distribution of each taxon (Mittermeier et al. 2000; IUCN 2012, 2024). The Top 25 list is supposed to reach a balanced representation both geographically, between the four major primate habitat regions (Africa, Asia, Madagascar, and Neotropics), and taxonomically, considering the 17 families and 82 genera of the Order – usually, no more than one species by genus is listed in each edition (Reuter et al. 2021). Moreover, specific contexts are considered, such as taxa recently discovered, lack of existing conservation attention, possible benefits from media exposure, and conservation opportunities (Reuter et al. 2021). Furthermore, species can be removed from the list from one edition to the next without any improvement in their risk status (Schwitzer et al. 2017, 2019), precisely because another purpose of the list is to highlight the variety of species that face equally serious prospects for their survival (Schäffler et al. 2022). Despite the factors considered for the inclusion of a species in the Top 25 list, analyzing threats affecting candidate species for listing can provide insights for conservation planning, following conservation-oriented research (Wang et al. 2025). Geospatial data, such as land cover characterizations and changes, are increasingly available and have recently been used to identify threats and to include species in the list (Sutherland et al. 2004; Li et al. 2016; Ocampo-Peñuela et al. 2016). Although their relatively recent development means there was a limited opportunity to use them in previous assessments, these data sources are rapidly evolving and have the potential to help conservation science achieve greater conservation benefits (Williams et al. 2020).

The challenges for primate conservation have become more critical since the beginning of the 21st century, when the Top 25 list began to be published. In 2000, almost 20% of the world’s primates were at risk of extinction, mainly due to habitat loss and hunting (Mittermeier et al. 2000). Despite high rates of deforestation and hunting in tropical regions, the first publication of the list celebrated the entry into the 21st century without documenting the extinction of any primate taxa in the previous century (Mittermeier et al. 2000; Ceballos et al. 2015). However, the publication highlighted the challenges of maintaining primate diversity in this context. Even in the absence of species-level extinction, population-level extinctions already outpace the rate at which species are listed as threatened (Hughes et al. 1997; Ceballos and Ehrlich 2009; Estrada and Garber 2022). These local declines undermine ecosystem functioning and signal early stages of species extinction (Ceballos and Ehrlich 2009; Cosby et al. 2025; Yang et al. 2025). Twenty years after the first Top 25 list, 93% of primate populations are in decline (Estrada and Garber 2022), and 65% of the species are threatened with extinction (Estrada and Garber 2022; Fernández et al. 2022). More than 230 taxa, i.e., nearly a third of the world’s primates, are categorized as Critically Endangered or Endangered and would, therefore, be eligible for inclusion in the Top 25 list.

The menaces that justify the inclusion of Brazilian primates in the threatened categories are ongoing (e.g., habitat loss and fragmentation and hunting) and/or emerging (e.g., climate change and disease outbreaks) (Estrada et al. 2017, 2018, 2019; Bernard and Marshall 2020; Fernández et al. 2022; Pinto et al. 2023). Although these threats are well understood and documented, studies that characterize species’ threats quantitatively and comparatively could be used to justify new conservation actions or support conservation campaigns for species at risk of extinction, considering at least the species’ biomes (Ocampo-Peñuela et al. 2016; Reuter et al. 2021; Matte et al. 2024). First, the unique characteristics of use and coverage of Brazilian biomes directly influence the availability, loss, and fragmentation of primate habitats (Navarro and Molina 2021; Fernández et al. 2022; Matte et al. 2024). Second, tackling the climate and biodiversity crises with limited conservation funding requires researchers and decision-makers to develop more cost-effective solutions capable of identifying species at greater risk of extinction through spatial analyses to remove them from this situation (Polaina et al. 2019; Mallapaty 2022; Eppley et al. 2024).

The prioritization process - determining which 25 species among many should receive greater investment opportunities in research and conservation - is not necessarily hierarchical; that is, it does not always involve a quantitative analysis to rank species according to urgency or need (Le Berre et al. 2019; Acerbi et al. 2020). This decision is mainly based on recent research, whose results are still not taken into account in IUCN assessments or in in-depth studies that address species individually, such as Bicca-Marques et al. (2020) and Possamai et al. (2022). On the other hand, the species hierarchy process defines an order of greatest species vulnerability (Le Berre et al. 2019; Matte et al. 2024) after considering how threats vary between species, following a comparative approach (Collen et al. 2016; Li et al. 2016; Ocampo-Peñuela et al. 2016; Da Silva et al. 2022; Matte et al. 2024). This comparative framework is especially useful for long-lived species with low reproductive rates, which often exhibit delayed responses to habitat changes – meaning that population declines or range contractions may become evident only long after initial disturbances (Purvis et al. 2000; Metzger et al. 2009; Ocampo-Peñuela et al. 2016; Semper-Pascual et al. 2018; Polaina et al. 2019; Galán-Acedo et al. 2023). Therefore, integrating landscape-scale data - such as habitat availability, fragmentation, and human pressures - can help refine species hierarchization and inform global conservation lists, such as the Top 25 list, based on comparative threat assessments to improve conservation mechanisms (Wang et al. 2025).

Here, we analyzed whether the landscape attributes of Brazilian primates in the Top 25 lists differ from those of threatened Brazilian primates never included in this list. Our main goal was to understand how the evaluated landscape attributes reveal risks to listed and unlisted species, and to determine whether species inclusion on the list reflects expectations of greater exposure to landscape threats. Various threats identified at the landscape scale can act simultaneously on the populations of a species within its range. Therefore, when we quantify the magnitude of these threats, we can suggest that some species are more or less exposed to threats. We also reviewed all published Top 25 lists from 2000 to 2022 and identified those that included Brazilian primates to examine the frequency and temporal patterns of Brazilian species being featured in the international spotlight. The frequency with which Brazilian primates appear on Top 25 lists could provide insights into which biomes and species are prioritized in this listing, with a potential bias towards species categorized at the highest extinction risk levels (specifically, the Critically Endangered and Endangered categories). Additionally, documented variation in habitat loss among Brazilian biomes reflects differences in biome-level conservation status (Rosa et al. 2021; Da Silva Arruda et al. 2024; Cortinhas Ferreira Neto et al. 2024; Franca Rocha et al. 2024). Given the strong link between habitat loss and extinction risk, we hypothesized that species from more degraded biomes (in this study, this means they have the greatest habitat loss) would be more frequently featured in the Top 25 lists over time.

In summary, our objective was to elucidate: i) whether species included in the Top 25 list face greater landscape-level threats compared to threatened species not included in the list; (ii) whether species representation in the Top 25 list is associated with their IUCN threat category (Critically Endangered [CR], Endangered [EN], Vulnerable [VU]), with higher-risk species being more likely to be listed; and (iii) whether the number of species entering or exiting the Top 25 list per biome is correlated with temporal changes in habitat availability within that biome (i.e., with greater losses of habitat cover over time).

Targeted animals

We analyzed 13 primate species that occur in Brazil and that were listed in the Top 25 lists published between 2000 and 2022 (Supplementary material 1A). We compared them with the 23 species and subspecies of threatened Brazilian primates categorized as Critically Endangered (CR), Endangered (EN), or Vulnerable (VU), but that were never included in the Top 25 lists (Supplementary material 1B). We used the most up-to-date IUCN Red List categorization to select threatened species (see: https://www.iucnredlist.org/). In our analysis, we assigned each primate species to the biome that overlapped with more than 50% of its range size (following Matte et al. 2024), thereby identifying which biomes had more frequently listed species (Supplementary material 1).

To assess whether species in higher IUCN threat categories were more frequently represented in the Top 25, we classified species according to IUCN extinction risk categories and used the species’ range size to delimit the landscape they occupied. The range size was used as a standardized measure of the spatial extent occupied by each species’ populations in Brazil and corresponds to the Extent of Occurrence criterion (Criterion B) of the IUCN Red List (IUCN 2024). Hereafter, we refer to this measure as range size.

Landscape attribute data

We quantified landscape attributes for 36 threatened Brazilian primate species (considering both listed and unlisted species), using ranges restricted to the Brazilian territory (ICMBio 2023). The polygons representing species’ range size were provided by the National Center for Research and Conservation of Brazilian Primates (CPB/ICMBio). To refine the delimitation of the distributions, CPB/ICMBio staff applied a Minimum Convex Polygon (MCP) approach constrained by rivers and forest fragment boundaries as constraints for the polygons (Matte et al. 2024). We, therefore, used these adjusted distribution polygons, which incorporate terrain features and represent refined post-MCP estimates of species’ range size.

To evaluate whether species included in the Top 25 list are exposed to greater landscape-level threats, we first characterized the landscapes occupied by each species. We defined their environment as the area covered by their range map, which we divided into a 100 km × 100 km grid of landscape units. From this combined set of landscape units, we extracted a suite of spatial variables to serve as landscape predictors in subsequent hypothesis testing. These included: (1) the available habitat; (2) the areas with less than 30% habitat cover (as a proxy for habitat fragmentation); (3) the habitat loss between 1987 and 2017 (30-year loss); (4) the habitat loss between 2007 and 2017 (10-year loss); (5) the area occupied by roads; (6) and urban infrastructure; and (7) the species’ range overlapping with the Arc of Deforestation and with Amazonian Indigenous Lands (see Supplementary material 2 to access the description of the landscape attributes methodology). The available habitat refers to the proportion of habitats in 2018 (forest, savanna with vegetation taller than 5 m, and mangroves), derived from the land use and land cover map with 30 m spatial resolution (Souza Jr. et al. 2020). Then, using all 100 km by 100 km landscape units within each species’ range map, we calculated the average percentage of each landscape predictor to enable comparisons of threat magnitude across species with varying range sizes. See Matte et al. (2024) for further details on the methodology for extracting landscape attribute data (Fig. 1), which is also explained in Supplementary Material 2. We obtained landscape attributes in ArcGIS 10.7 (Esri 2019).

To test whether species from more threatened biomes were more frequently listed, we calculated the amount of habitat available in each biome where species listed and unlisted occur (Amazon, Caatinga, Cerrado, and Atlantic Forest) for the periods related to the editions of Primates in Peril (see Supplementary material 4). We extracted the habitat proportion for each biome using the same 100 km grid used to quantify landscape attributes within the species’ range. However, in this analysis, we clipped the 100 km grid according to the boundaries of the Atlantic Forest, Caatinga, Cerrado, and Amazon biomes (see Supplementary material 4).

Data analysis

We conducted a Principal Component Analysis (PCA) using the vegan package in RStudio version 2024.12.0. (R Core Team 2021) to pre-access (i) which landscape-level threats are faced by listed and unlisted species; (ii) whether the most threatened species (Critically Endangered (CR), Endangered (EN), Vulnerable (VU)) were disproportionately represented in the Top 25 list; and (iii) whether species most frequently listed tend to inhabit the most threatened biomes, such as the Atlantic Forest. We implemented the PCA using a correlation matrix based on landscape predictors, all measured as percentages. We treated primate species as sampling units, classified according to three criteria: (1) whether they were listed or unlisted in the Top 25 list; (2) their IUCN threat status—Critically Endangered (CR), Endangered (EN), or Vulnerable (VU); and (3) their predominant biome—Amazon, Caatinga, Atlantic Forest, or Cerrado. Since PCA reduces data dimensionality into principal components, we extracted the scores of the first two principal components—those summarizing the main variation in landscape attributes across primate species—to visually assess how listed and unlisted species group or differ in multivariate space.

To support the PCA results and identify whether there were significant differences in the landscape characteristics of the threatened Brazilian primates listed and unlisted in the Top 25 lists, we conducted a Permutational multivariate analysis of variance (PERMANOVA) with two factors: Top 25 list (with two levels: listed and not listed) and biome (With four levels: Amazon, Atlantic Forest, Cerrado and Caatinga) using PRIMER 7.0 software with PERMANOVA+ (Clarke and Gorley 2015).

Additionally, to examine the relationship between species representation in the Top 25 list and their IUCN threat categories (CR, EN, VU), we categorized each of the 36 species by their IUCN status and Top 25 listing status (presence/absence). We then used a chi-squared test to assess the independence of these categorical variables using Microsoft Excel (Microsoft Corporation 2025).

Lastly, we evaluated whether the number of species entering/exiting the Top 25 list per biome correlated with temporal changes in habitat availability in that biome from 1998 to 2022. Habitat changes among the Top 25 list publications were measured and tested for significance using ANOVA for repeated measures in PAST5 (Hammer et al. 2001). Habitat variation within each biome was then associated with species-list dynamics (entry/exit) using Spearman’s correlation.

Landscape attributes - Listed and unlisted species in the Top 25 list

We found that the landscape attributes for species listed and not listed in the Top 25 lists do not differ from one another, even when we consider the biome as one of the factors (Fig. 2 and Table 1). The first two axes of the PCA explained 70% of the variability among species based on their landscape attributes (Fig. 2a). The first principal component (PC1) captures a gradient from landscapes with high road coverage (r = –0.88) and fragmentation (r = –0.73), associated with negative scores, to those with greater overlap with the Arc of Deforestation (r = 0.72), associated with positive scores (Fig. 2b). The second principal component (PC2) captures a gradient from landscapes with high habitat loss in the last 10 years (r = 0.83) and 30 years (r = 0.80), associated with positive scores, as well as high habitat availability (r = -0.71) and high overlap with Amazonian indigenous lands (r = -0.59), the latter associated with negative scores (Fig. 2b). The PCA does not suggest a clear distinction in landscape attributes between listed and unlisted primate species, as we observed an overlap between the points of listed and unlisted species in the multidimensional space defined by this set of landscape attributes (Fig. 2a). Both groups occupy landscapes with a high proportion of roads, high habitat fragmentation, and significant overlap with the Arc of Deforestation. However, along axis 2 (positive scores), we can identify species that have experienced a higher proportion of habitat loss over the past 30 years. These include Callicebus barbarabrownae and Cebus kaapori (among the primates already listed), as well as Chiropotes satanas, Chiropotes utahickae and Callicebus coimbrai (among primates not included in the Top 25 list; Figs. 2 and 3 in Supplementary Material 3 provide the identification of both listed and unlisted species belonging to the group most affected by habitat loss over the last 30 years, and therefore potentially of higher priority for conservation efforts).

When analyzing landscape attributes from the perspective of species’ IUCN threat categories, we did not observe a clear distinction between species listed in higher threat categories compared to those not listed (Fig. 2a and 2c). This shows that the landscape attributes of species in the CR category resemble those of other threat categories, even though the CR category is the highest-risk category. Another group of species that has emerged comprises unlisted Amazonian species with greater habitat availability (Fig. 2). These species belong to the IUCN’s “Endangered” and “Vulnerable” categories and are subject to hunting, with a wide distribution within the Amazon’s indigenous lands (Fig. 2).

Most primate species included in the Top 25 lists occur predominantly in the Atlantic Forest and Caatinga biomes, although biome-based groupings do not strictly align with listing status (Fig. 2d). We also highlight that the landscape attributes of species with greater distribution in the Caatinga, Atlantic Forest, and Cerrado are more similar to one another, with a high proportion of habitat fragmentation, roads, and low habitat availability when compared to Amazonian species (Fig. 2d and Figure 2_Supplementary Material 3). Amazonian species, on the other hand, are more heterogeneous, as we identified a group that suffered high habitat loss and occurs in the Arc of Deforestation (Fig. 2a, d), and another group that occupies well-preserved landscapes that overlap with indigenous lands (Fig. 2a, d).

Our PERMANOVA analyses indicated that landscape attributes did not significantly differ between species listed in the Top 25 lists and those not listed, even when the biome was included as a factor (Table 1). Therefore, PERMANOVA corroborates the PCA result, demonstrating that the inclusion of species in the list does not reflect greater exposure to threats in the landscape occupied by these species.

Representation in the Top 25 list and the IUCN threat category

Our chi-square test revealed a significant association between inclusion in the Top 25 list and IUCN threat categories (Critically Endangered [CR], Endangered [EN], Vulnerable [VU]) (χ² = 14.25, degrees of freedom (df) = 2, P < 0.0008). The results indicate that Brazilian species classified in higher IUCN threat categories, such as Critically Endangered and Endangered, were more frequently represented among the Top 25 most endangered primate species listings, compared to the Vulnerable category, which are more common in the group of unlisted ones.

Biome threat and species listed in the Top 25 list

Eight out of the 13 listed Brazilian primate species are predominantly found in the Atlantic Forest, two in the Caatinga, and three in the Amazon (Supplementary material 1A and Fig. 3). Among the 23 unlisted species, six occur predominantly in the Atlantic Forest, 15 in the Amazon, one in the Caatinga, and one in the Cerrado (Supplementary material 1B). The first edition of the Top 25 list, published in 2000, included five Brazilian species—the highest number recorded to date (Fig. 3). Several Brazilian primates appeared in multiple editions of the list, with some species consistently included in the same set from 2002 to 2006 and again from 2014 to 2018 (Fig. 3). Notably, no Brazilian species were included in the 2008–2010 edition of the Top 25 list (Fig. 3).

For the Caatinga biome, repeated measures ANOVA showed no difference in habitat availability over the analyzed period (i.e., 1998 to 2022) (F(12;3372)=1.362, p=0.1767). Additionally, Spearman’s correlation found no relationship between habitat changes and the number of Caatinga primates entering/exiting the Top 25 list (rs=0.2091, p=0.5143), suggesting that fluctuation in the amount of habitat availability did not correlate with listing dynamics.

For the Atlantic Forest biome, repeated measures ANOVA revealed significant differences over the analyzed period (F(12;13152)=42.74, p<0.0001), indicating a modest, gradual habitat recovery with a 1.2% increase in habitat availability. However, Spearman’s correlation showed no significant relationship between this habitat increase and the number of Atlantic Forest primates entering/exiting from the Top 25 (rs=0.0287, p=0.9294), suggesting the gradual habitat gain did not correlate with listing dynamics.

For the Cerrado biome, repeated-measures ANOVA showed significant differences over the analyzed period (F(12;11460)=35.85, p<0.0001), indicating a gradual habitat loss with a final decrease of 0.24% in habitat availability. Cerrado species were never included in the Top 25 list.

For the Amazon biome, repeated-measures ANOVA revealed significant differences over the analyzed period (F(12;9408)=158.1, p<0.0001), showing a gradual habitat loss with a final net change of -4.45% in habitat availability. Spearman’s correlation found no significant relationship between this habitat loss and the number of Amazon primates entering/exiting from the Top 25 list (rs=-0.064, p=0.8428), indicating the habitat decline did not correlate with listing dynamics.

Thus, overall, we found that fluctuations in primate habitat availability within each biome did not correlate with the Top 25 listing dynamics for Brazilian primates. Changes in the average proportion of available habitat within each biome from 1998 to 2022 are presented in Supplementary Material 4.

Our findings indicate that Brazilian primate species in the Top 25 lists faced landscape-level threats similar to those of species not listed. We confirmed that Critically Endangered and Endangered species were included more frequently in the Top 25 lists, and we highlighted the similarity between the landscape attributes (such as habitat availability and threats) that placed this group at greater risk and those experienced by Vulnerable primate species that were never included in these lists. This may encourage experts and managers to adopt this type of analysis, which ranks species based on quantified landscape attributes to identify the world’s most threatened species. Additionally, our study shows that the loss or gain of habitat cover in biomes between 1998 and 2022 did not correlate with the inclusion or removal of species from the Top 25 lists (see Supplementary Material 4). Therefore, the loss of habitat cover in each biome did not influence the inclusion of its species on the list, nor did the landscape attributes that characterize the areas occupied by primate species. Although this result might be expected, given that experts balance the criteria underlying the IUCN threat category—geographic and taxonomic representation—we provide important confirmation of the landscape conditions that drive the species’ threatened status, which may worsen over time.

We identified that the listed and unlisted species with the greatest habitat losses over the last 10 and 30 years are mainly Amazonian (represented on axes 1 and 2, with positive scores; Fig. 2 and Supplementary Material 3). Additionally, the Amazon was the biome with the greatest loss of available primate habitat between 1998 and 2022, when we analyzed the biome as a whole, due to the role of cattle ranching, soybean cultivation, and illegal mining in driving Amazon deforestation (Cortinhas Ferreira Neto et al. 2024; Leite-Filho et al. 2024). This was accompanied by an increase in the number of species listed in the editions of Primates in Peril (Plecturocebus grovesi and Saguinus bicolor - Supplementary material 1).

Notably, when we analyze the amount of habitat available for primates in the Atlantic Forest, we see a modest recovery between 1998 and 2022. This was also observed in other studies that assessed the native forest cover of Atlantic Forest during 1990-2017 (Rosa et al. 2021) and 1986-2020 (Vancine et al. 2024), with the greatest continuous loss of older native forests and an increase in younger native forest cover, even though the forest also became more fragmented, associated with the progressive rejuvenation of native forest cover (Rosa et al. 2021; Vancine et al. 2024). This result gives another meaning to expectations regarding the quantity and loss of forest habitat in the Atlantic Forest in relation to historical conversion and the challenges for restoring these habitats (Rosa et al. 2021). When we analyze the landscape attributes of Atlantic Forest species, we observe that most are not characterized by the greatest loss of habitat in the last 10 and 30 years (axes 1 and 2 - positive scores), but rather by the highest proportion of roads, urbanized areas, and, consequently, fragmented areas (axis 1 - negative scores) (see Fig. 2 and Supplementary Material 3), with some representatives of the Caatinga having similar characteristics (also on axis 2 - positive scores). The landscape defined by species range may reflect local characteristics experienced by these species in ecosystems where there has been historical habitat loss, such as in the Atlantic Forest and Caatinga, or recent usage trends detected in the biome, such as in the Amazon and Cerrado - the latter also suffered from the effects of the recent expansion of agriculture and increased susceptibility to fires (Da Silva Arruda et al. 2024). In this regard, we highlight the importance of the Top 25 lists in including species from the Atlantic Forest and Caatinga biomes over the last 20 years, aiming to reverse this scenario.

The inclusion of species in the Top 25 list balances IUCN assessment criteria (Mittermeier et al. 2000; IUCN 2012, 2024), geographical and taxonomic representation (Reuter et al. 2021), and factors like recent discoveries, conservation needs, media exposure, and conservation opportunities (Acerbi et al. 2020; Reuter et al. 2021). Notably, certain Brazilian species appear repeatedly across Top 25 editions, such as Leontopithecus caissara, Brachyteles hypoxanthus, Alouatta guariba guariba, Sapajus xanthosternos, and Cebus kaapori. The two-year period between each edition of the list is indeed too short to reflect the achievement of conservation objectives or the effective reduction of threats, which partially justifies the recurrences. And so we continue to observe that threats persist, keeping the species at risk of extinction, even after 20 years of inclusion on the Top 25 list, highlighting the severity of the threats, the complexity of reversing them, reflecting that not all species listed may have received the expected support for their conservation, and confirming that biodiversity continues to decline, as shown by other studies (e.g., Mace et al. 2018; Wang et al. 2025).

The Top 25 list aims to spotlight species facing serious survival challenges, encompassing not just narrow-range species but also widely distributed ones like A. guariba and S. xanthosternos, which experience population declines due to severe habitat fragmentation (Supplementary material 3) (Schäffler et al. 2022). We underscore the heightened complexity of managing threats for these broadly distributed species, given their presence across multiple states and municipalities. For species spanning biomes, states, and municipalities, coordinated efforts are critical to ensure effective conservation, as political boundaries can disrupt ecological connectivity with significant environmental repercussions. Strengthening cross-border conservation action plans – between and within municipalities and states – is essential to collectively safeguard ecosystems, species, and resources, thereby preserving ecological connectivity (Kamath et al. 2023).

Being included on the Top 25 list can boost research and conservation efforts, as seen in species such as Leontopithecus caissara and Sapajus flavius, which benefited from increased research, public policies, and reclassification from Critically Endangered to Endangered (Ludwig et al. 2021; Nascimento et al. 2021; Valença-Montenegro et al., 2021). Nevertheless, such changes in conservation status often reflect improved data and assessment methods rather than a reduction in threats per se (Eppley et al. 2024). Our findings underscore the need for systematic threat assessments to identify Brazil’s most vulnerable species and inform global conservation listings (Sutherland et al. 2004; Ocampo-Peñuela et al. 2016; Butti et al. 2022). By mapping range-specific threats and prioritizing species, we can optimize conservation efforts, especially with limited resources (Collen et al. 2016; Azevedo-Santos et al. 2017; Le Berre et al. 2019), and monitor the effectiveness of actions (Junker et al. 2020).

The relatively long generation time of primates implies that the recovery of their populations will take a long time to be reflected, according to IUCN criteria (Watts et al. 2020; Wang et al. 2025). For this reason, when prioritizing species, we must consider other attributes in addition to threats to the landscape, as these attributes place listed threatened species at greater risk. Life history traits such as generation time and reproductive rate, for instance, will be decisive in making primates even more vulnerable to habitat changes (Spaan et al. 2020). Larger threatened primates, e.g., with a generation time of more than 15 years, tend to show a delayed response to habitat changes, reproduce more slowly, and their subpopulations may already accumulate the deleterious effects of population reduction mentioned above, even if they are not detected in the field (Semper-Pascual et al. 2018; Galán-Acedo et al. 2023). Therefore, it is essential to reconsider the inclusion of species belonging to the genus Sapajus (with a generation time of 16 years) that are no longer listed, and that occupy more fragmented areas with a high proportion of roads in the Atlantic Forest and Caatinga. As well as those never listed from the genera Ateles and Lagothrix (generation time of 15 years), which, in addition to occurring in the Arc of Deforestation, are hunted and would have a slower recovery from the drastic declines of their populations (Liow et al. 2008). Although primates in anthropogenically modified areas often have higher rates of hunting than those in relatively undisturbed areas (Peres 2001), the effect of hunting on these species may still be underestimated. Therefore, to assess the priorities for these hunted species, it is essential to distinguish the effects of habitat loss from those of different types of hunting, both commercial and subsistence.

We emphasize the importance of assessing threat magnitude across species’ entire range sizes to identify critical landscape contexts impacting populations, and also relate whether what occurred in the landscape occupied by the species reflects what occurred in the biomes. Thus, we identified that species from the Atlantic Forest and Caatinga experience threats at different levels than biome-level analyses reveal, or else reflect recent land use trends, such as Amazonian and Cerrado species. Removal from the Top 25 list often doesn’t signify improved conservation status; rather, it reflects the initiative’s dynamics amidst many endangered primates requiring attention. Threats persist and intensify for known populations, exposing them to high extinction risk, even for species like Sapajus flavius, Sapajus xanthosternos, Leontopithecus chrysopygus, Leontopithecus rosalia, and Callicebus barbarabrownae – species removed from the list – and unlisted species in anthropized landscapes. Our findings underscore the severity of threats faced by most primates and the complexity of prioritizing species, particularly in megadiverse Brazil. We provide an analytical approach to help with the selection of Brazilian species for further editions of the "Primates in Peril: The World’s 25 Most Endangered Primates”, aiming to extend the potential conservation benefits to other species than the already selected that are facing similar landscape contexts. To enhance conservation outcomes, refining the selection process for the Top 25 list could involve not only the severity of threats within Brazilian species’ range – using a comparative approach to prioritize highly threatened species – but also incorporating additional criteria such as temporal habitat loss patterns across biomes. Even subtle biome-specific differences might help identify particularly vulnerable biomes, allowing for more targeted and effective conservation strategies.

Authors

1. Ana Luiza L. Matte
2. Leandro Jerusalinsky
3. Gerson Buss
4. Pedro Pequeno
5. Paulo Santos
6. Bruna Bezerra

Cite this article

Matte, A.L., Jerusalinsky, L., Buss, G. et al. Landscape attributes for all of Brazil’s threatened primates are similar to those listed among the World’s 25 most endangered primates. Biodivers Conserv 35, 194 (2026). https://doi.org/10.1007/s10531-026-03384-y

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• Received: 01 April 2025

• Revised: 16 May 2026

• Accepted: 25 May 2026

• Published: 25 June 2026

• Version of record: 25 June 2026

• DOI: https://doi.org/10.1007/s10531-026-03384-y

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