Moisture-laden air moving inland across South America from the Atlantic Ocean nourishes one of the continent’s most diverse biomes, the Atlantic Forest (Mata Atlântica in Portuguese). Formerly extending across c. 1.3 million km² in Brazil, Argentina and Paraguay, this biodiversity hotspot encompasses a range of elevations, climatic regimes, geological formations and soil types. The environmental heterogeneity has given rise to rainforests, mixed montane forests, mangroves, coastal woodlands (restingas), montane grasslands and rocky outcrops (campos rupestres and inselbergs; Joly et al., Reference Joly, Scarano, Seixas, Metzger, Ometto and Bustamante2019; Marques & Grelle, Reference Marques and Grelle2021). The Atlantic Forest is home to more than 16,000 plant and 2,400 vertebrate species, of which c. 10 and 25% are threatened, respectively (Joly et al., Reference Joly, Scarano, Seixas, Metzger, Ometto and Bustamante2019). The high proportion of threatened species is a result of centuries of exploitation, a large human population, and high rates of deforestation associated with logging, sugar cane, coffee and cocoa plantations, agricultural crops and pastures (Marques & Grelle, Reference Marques and Grelle2021). By the 21st century, almost 90% of the original vegetation had been lost (Ribeiro et al., Reference Ribeiro, Metzger, Martensen, Ponzoni and Hirota2009). In addition, the Atlantic Forest is threatened by climate change and invasive species, and large metropolitan areas intensify pressures from urbanization and pollution (Joly et al., Reference Joly, Scarano, Seixas, Metzger, Ometto and Bustamante2019; Marques & Grelle, Reference Marques and Grelle2021).

The context in which the Atlantic Forest is situated is a challenge for researchers, conservationists and policymakers alike. This issue of Oryx addresses this challenge through three of the main global threats to biodiversity—land-use change, biological invasions and overexploitation—focusing in particular on endemic and threatened species. Five new articles (Cardoso et al., Reference Cardoso, Bicalho, Fernandez, Ferreira, Menini-Neto and Trovó2025; Fernandes et al., Reference Fernandes, Machado, Ferreira, Vasconcelos, Lucas and Braga2025; Guimarães-Lopes et al., Reference Guimarães-Lopes, Loureiro, Damo, Melo, Rodrigues and Massara2025; Grittz et al., Reference Grittz, Lima, Filho, Vibrans and Gasper2025; Sabino et al., Reference Sabino, Kamimura, Marcusso, Koch, Shimizu and Pinheiro2025) and a selection of recently published articles address monitoring, extinction risk, reintroduction and translocation, and new records and species rediscoveries. Beyond drawing attention to anthropogenic impacts on biodiversity, we use this overview to commend actions to inspire future study and conservation initiatives.

Regarding habitat loss, fragmentation and degradation resulting from land-use change, Costa-Araújo et al. (Reference Costa-Araújo, Regolin, Martello, Souza-Alves, Hrbek and Ribeiro2021) used the Vulnerable black-handed titi monkey Callicebus melanochir, endemic to the Atlantic Forest, as a model to evaluate the effects of forest patch and landscape structure. Although patch quality and landscape connectivity positively influence the species’ occurrence, patch area was the best predictor of presence. As large forest remnants are scarce in the Atlantic Forest, such baseline data are required to support conservation management in small forest fragments.

Considering the effects of forest quality and hunting pressure, Rios et al. (Reference Rios, McGowan, Collar, Benchimol, Canale, Santos-Filho and Bernardo2020) studied the Endangered and also endemic red-billed curassow Crax blumenbachii in forest fragments. They found that hunting pressure potentially exerts the greatest negative influence, although these populations are also, albeit less intensively, influenced by landscape features. Where hunting pressure is driving declines, areas with low human presence and high forest cover are needed for conservation.

Focusing on biological invasion, in Rio Doce State Park Guimarães-Lopes et al. (Reference Guimarães-Lopes, Loureiro, Damo, Melo, Rodrigues and Massara2025) confirmed the impact of Geoffroy’s tufted-ear marmoset Callithrix geoffroyi (native to other areas of the Atlantic Forest) and the black-pencilled marmoset Callithrix penicillata (native to the Caatinga and Cerrado) on the buffy-tufted-ear marmoset Callithrix aurita, endemic to the Atlantic Forest. Of the 139 individuals identified, only one was a native C. aurita free from hybridization. Management is required to conserve any remaining C. aurita.

In a rapidly changing world, overcoming technical barriers and advancing extinction risk assessments are essential for understanding how, and how severely, species are threatened. The forest canopy is a challenging location in which to work, but some of the difficulties can be overcome with arboreal camera trapping (Kaizer et al., Reference Kaizer, Alvim, Novaes, McDevitt and Young2022). Surveying mammals in the canopy revealed patterns of diversity, including of threatened species, that would otherwise remain hidden. Using ecological and distributional data to refine Red List assessments for herbs and trees revealed alarming declines and identified areas where conservation actions are most urgently needed (Cardoso et al., Reference Cardoso, Bicalho, Fernandez, Ferreira, Menini-Neto and Trovó2025; Grittz et al., Reference Grittz, Lima, Filho, Vibrans and Gasper2025).

Recent conservation initiatives combining in situ and ex situ strategies demonstrate the potential to rewild the Atlantic Forest, mitigating defaunation and plant extirpation, and restoring ecosystem services. Reintroduction programmes targeting key species, such as the Critically Endangered northern muriqui Brachyteles hypoxanthus (de Melo et al., Reference de Melo, Tabacow, Pereira, Mendes, Chaves and Moreira2024) and red-rumped agouti Dasyprocta leporina (Kenup et al., Reference Kenup, Sepulvida, Kreischer and Fernandez2018), illustrate how integrated actions can rebuild ecological interactions and ecosystem function. Plant-focused interventions, such as the reintroduction of Melocactus violaceus (Caitano et al., Reference Azevedo, de Pasa, Kunz, Campos, Batita and Ribeiro2022) and Grazielanthus arkeocarpus (Peixoto et al., Reference Peixoto, Peixoto, de Almeida, Gonzaga and de Lírio2023), can reinforce natural populations and secure species persistence.

Despite extensive study, the Atlantic Forest remains a source of remarkable biological discoveries and conservation opportunities. Across its mosaic of rainforests, rocky outcrops, insular remnants and urban areas, discovery and rediscovery are still part of its story. Plant species once considered lost can yet be found in isolated or unexpected habitats (Paglia et al., Reference Paglia, Luber, Mansano and Freitas2022; Fernandes et al., Reference Fernandes, Machado, Ferreira, Vasconcelos, Lucas and Braga2025; Sabino et al., Reference Sabino, Kamimura, Marcusso, Koch, Shimizu and Pinheiro2025), and knowledge of the rare bush dog Speothos venaticus continues to improve (Azevedo et al., Reference Caitano, Dutra, Valadares and Calazans2025). These findings, both hopeful and sobering, remind us that conservation in the Atlantic Forest is not only about protecting what we already know, but also about continuing to research, document and understand what remains hidden in the last fragments of this extraordinary biome.

The studies in this issue illustrate the breadth of efforts and perspectives needed to conserve the Atlantic Forest. Addressing the threats of climate change and invasive species, and their synergistic effects, alongside improving knowledge of biodiversity, implementing large-scale restoration, and integrating management of invasive and threatened species, are all crucial. Researchers, conservationists and policymakers must scale up conservation actions in space and time, and across taxa, landscapes and ecosystems. Securing the future of the Atlantic Forest will require not only a robust foundation of knowledge, such as the work highlighted in this issue, but, above all, the translation of that knowledge into coordinated and integrated conservation action.

We thank Martin Fisher for editorial advice. CJL received a grant from the Conselho Nacional de Desenvolvimento Científico e Tecnológico (grant number 150420/2024-2).

This Editorial and the Oryx articles cited are available as a virtual issue at cambridge.org/core/journals/oryx/virtual-issues.

Editor’s note: The way in which readers locate conservation news is evolving, and therefore, after many years of loyal service, we are retiring the Briefly section from this issue onwards.