Fragmented Forests Fail to Support Diverse Bird Populations

Study finds surrounding landscape quality is key to conservation of tropical and subtropical forest birds

Apr. 7, 2026 at 9:08am

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A highly textured, abstract painting in soft earth tones of green, brown, and blue, featuring sweeping geometric arcs, concentric circular patterns, and precise botanical spirals, conceptually representing the complex interplay between forest fragments, surrounding matrix, and bird biodiversity.An abstract visualization of the critical role that the landscape surrounding forest fragments plays in supporting diverse bird populations, as revealed by new research.Slippery Rock Today

A study analyzing over 1,000 forest fragments in the tropics and subtropics has found that the diversity of bird species declines fastest when these habitat patches are surrounded by areas inhospitable to woodland birds, even if the forest fragments themselves are relatively large. The research suggests that investing in more tree cover and wildlife-friendly practices in the areas surrounding protected forest remnants could greatly increase their conservation value.

Why it matters

Biodiversity loss is a major global crisis, with almost 25% of assessed animal and plant species threatened worldwide. This study provides important insights into how to better protect vulnerable bird populations in fragmented forest habitats, which are critical for maintaining healthy ecosystems and the ecosystem services they provide.

The details

The international research team combined data from forest islands created by river damming and forest fragments created by clear-cutting. They found that even tiny forest fragments just a few acres or less can hold conservation value if the surrounding landscape, known as the 'matrix', has moderate tree cover. However, the value of these forest remnants goes up significantly when the matrix is more hospitable to woodland birds. The magnitude of decline in species richness depends on how specialized the birds are to their habitat and the quality of the surrounding matrix.

  • The study analyzed 50 datasets from more than 1,000 individual parcels of tropical and subtropical forest.
  • The findings were published in the Proceedings of the National Academies of Sciences in 2026.

The players

Matthew Betts

A researcher at the Oregon State University College of Forestry and co-author of the study.

Carlos Peres

A co-author of the study from the University of East Anglia in England.

Anderson S. Bueno

A project co-lead from Brazil's Instituto Federal de Educação, Ciência e Tecnologia Farroupilha (Federal Institute of Science and Technology Education in Farroupilha).

Chase D. Mendenhall

A project co-lead from Slippery Rock University in Pennsylvania.

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What they’re saying

“Contrary to what some people have thought, our research shows that pockets of small protected areas, by themselves, aren't enough to enable robust avian conservation efforts in the biodiversity-rich forests of the tropics and subtropics.”

— Matthew Betts, Researcher, Oregon State University College of Forestry

“The research shows that conservation gains from investing in a more hospitable matrix in agricultural and urban areas are far greater than previously realized.”

— Carlos Peres, Co-author, University of East Anglia

“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.”

— Anderson S. Bueno, Project co-lead, Instituto Federal de Educação, Ciência e Tecnologia Farroupilha

“Ideally it will encourage governments and landowners to invest in wildlife‑friendly farming practices that support both biodiversity and agricultural productivity.”

— Chase D. Mendenhall, Project co-lead, Slippery Rock University

What’s next

The researchers hope the findings will result in more effective land-use policies that encourage wildlife-friendly farming practices to support both biodiversity and agricultural productivity.

The takeaway

This study highlights the critical importance of the landscape surrounding protected forest fragments in supporting diverse bird populations. By investing in increasing tree cover and implementing wildlife-friendly practices in these matrix areas, conservation efforts can be greatly enhanced, even for small forest remnants.