A major new study has revealed that improving the landscapes surrounding forest remnants can dramatically increase their ability to retain bird species - even when the forest fragments themselves are small or isolated.
For decades, traditional ecological theory has treated isolated habitat remnants as ‘islands’, predicting species’ survival largely through area size and isolation. But these models have long overlooked the nature of the ‘matrix’: the farmland, vegetation, or open areas surrounding these habitat remnants.
This surrounding landscape is critical, as species must move through, use, or avoid it when navigating between forested areas.
Now, new research published today in Proceedings of the National Academy of Sciences (PNAS) provides the strongest global evidence to date that the quality and structure of the matrix play a crucial role in biodiversity survival.
The study - led by scientists from the Instituto Federal de Educação, Ciência e Tecnologia Farroupilha in Brazil, Slippery Rock University in the US, and University of East Anglia (UEA) in the UK - shows that even modest increases in nearby tree cover can substantially boost the number of bird species that survive in forest remnants.
Prof Carlos Peres , from UEA’s School of Environmental Sciences , said: “This study clearly shows how high-quality surrounding landscapes increase species retention within forest remnants across the tropics. The conservation gains from investing in a more hospitable matrix in agricultural and urban areas are far greater than previously realised.”
Lead author Dr Anderson Bueno, from the Instituto Federal de Educação, Ciência e Tecnologia Farroupilha, said: “Habitat remnant size is not the whole story. Two forest remnants of the same size can support very different numbers of bird species - those surrounded by farmland with nearby trees may host more than twice as many species as isolated remnants within reservoirs.”
Dr Chase Mendenhall, of Slippery Rock University, added: “We hope our work will inform more effective land‑use policy and encourage governments and landowners to invest in wildlife‑friendly farming practices that support both biodiversity and agricultural productivity.”
Key findings
The study revealed three major insights:
A new pathway for conservation
The findings highlight that, while protecting remaining forests is essential, restoring and improving the landscapes around them is also critical. Planting native trees, restoring degraded vegetation, and creating wildlife-friendly agricultural land can dramatically reduce local extinction risks – which the authors say is a highly encouraging message given that humanmodified landscapes now cover more than half of Earth’s land surface.
A global effort
The research team brought together 58 scientists from 19 countries to analyse results from 50 landscape-scale bird surveys across tropical and subtropical regions in the Americas, Africa, and Asia - all areas where natural landscapes have been heavily fragmented.
The unique design of the study compared two types of forest remnants: forest islands created by hydroelectric reservoirs, which represent the most extreme habitat fragmentation on Earth, and forest fragments embedded within terrestrial landscapes, often surrounded by agricultural land.
By comparing these contrasting systems, the researchers could quantify how much a more benign, tree-rich matrix can buffer species against local extinctions.
Researchers surveyed more than 1000 forest remnants - 336 forest islands and 669 terrestrial fragments - and recorded almost 2000 bird species across nearly 40,000 separate incidence records. These included: five Critically Endangered species; 12 Endangered; 44 Vulnerable; 83 Near Threatened; and 1810 Least Concern species.
As well as using point counts, transect and walkabout surveys, mist netting, and passive acoustic monitoring, satellite imagery enabled the researchers to map tree cover around each site and determine the ‘neighbourhood scale’ of habitat that matters most for forestdependent birds.
‘High-quality surrounding landscapes mitigate avian extirpations from forest remnants’ is due to be published in Proceedings of the National Academy of Sciences on March 31, 2026.
Proceedings of the National Academy of Sciences
High-quality surrounding landscapes mitigate avian extirpations from forest remnants
31-Mar-2026