Diversified Farms Help Forest Birds in Costa Rica Study

Author: Stanford University
Published: 4 Sep 2023 - Updated: 4 Nov 2026
Publication Details: Peer-Reviewed | Environmental Science

Table of Contents:
Synopsis - Definition - Overview - FAQs - Insights, Updates - Related Content

Synopsis

This research from Stanford University, published in the peer reviewed Proceedings of the National Academy of Sciences in September 2023, tracked bird populations for 18 years across forests, diversified farms and intensive agriculture in Costa Rica, one of the longest-running studies of tropical wildlife. It found the steepest declines in forests, while a significant subset of forest bird species, including some of conservation concern, increased on smaller farms with mixed crops and strips of forest. Because birds control pests and help pollinate crops, the findings matter for food security and for farmers and policymakers seeking to protect nature outside parks.*

At a Glance

• 1 - About three-quarters of the world's crops depend on pollinators to some extent.
• 2 - Species doing well on intensive farms were often invasive rather than forest birds.
• 3 - Costa Rica set up the world's first countrywide payment for ecosystem services program.
• 4 - Forests now cover almost 60 percent of Costa Rica, up from 40 percent in 1987, according to the researchers.

Topic Definition

Diversified Farming

Diversified farming is an approach to agriculture that grows a variety of crops, often alongside livestock, hedgerows, trees or patches of natural habitat, rather than a single crop over large areas. It aims to sustain yields while supporting biodiversity, soil health and natural services such as pollination and pest control, and it can make farms more resilient to pests, disease and climate shocks.

Overview

"Diversified Farms Bolster Forest-Bird Populations Despite Ongoing Declines in Tropical Forests" - Proceedings of the National Academy of Sciences.

It seems intuitive that forests would provide better habitat for forest-dwelling wildlife than farms. Yet, in one of the longest-running studies of tropical wildlife populations in the world, Stanford researchers found that over 18 years, smaller farms with varying crop types - interspersed with patches or ribbons of forest - sustain many forest-dependent bird populations in Costa Rica, even as populations decline in forests.

In a paper published Sept. 4th, 2023, in the Proceedings of the National Academy of Sciences, Nicholas Hendershot and colleagues compared trends in specific bird populations across three landscape types in Costa Rica: forests, diversified farms, and intensive agriculture. The steepest declines were found in forests, then in intensive agriculture (and the species succeeding in intensive agriculture were often invasive). But on diversified farms, a significant subset of bird species typically found in forests, including some of conservation concern, actually increased over time.

"Birds are kind of a proxy we use to track the health of ecosystems. And the birds we're seeing today aren't the same as we saw 18 to 20 years ago. This paper really documents this pattern," said Hendershot, a postdoctoral fellow at the time of this research in Stanford's Department of Biology in the School of Humanities and Sciences (H&S), the Stanford Center for Conservation Biology (CCB), and the Stanford-based Natural Capital Project (NatCap).

Food Security at Stake

While this research implies that diversified farming could be key for biodiversity, the relationship goes both ways: biodiversity is key for food security. In this case, that means having a variety of types of birds feeding on insects and helping to pollinate crops.

"Identity does seem to matter a lot for pest control and other ecosystem services birds provide. These species are not interchangeable," said Hendershot.

"We need a constant stream of pollinators servicing farms. About three-quarters of the world's crops require pollinators to some extent, and that 75% is our most nutritious food - think of all the vitamins and minerals packed into fruits, nuts, and veggies," explained Gretchen Daily, faculty director of NatCap and CCB, Bing Professor of Environmental Science in H&S, and a senior author on the paper. "We need a constant stream of birds, bats, and other wildlife to help control pests: they suppress the vast majority naturally. And we need to start building flood protection, water purification, carbon storage, and many other vital benefits back into agricultural landscapes, way beyond what can be achieved in protected areas alone."

Daily also noted that, in terms of food production, diversified farms are not necessarily lower yielding than intensive agriculture.

"This is a recent assumption that is being overturned," she said.

Beyond Protected Areas

It has become increasingly apparent around the world that while protected areas remain critical, they are too few and far between to provide the ecosystem services people and nature need to thrive. Working landscapes are crucial now for preserving biodiversity and its benefits.

"People, including scientists, had the idea that farmland would not support a meaningful amount of biodiversity," said Daily. In this case, not only are diversified farms themselves providing habitat, they connect otherwise fragmented forested areas.

Over time, Hendershot said, "I have moved away from the 'fortress conservation' model, which focused more on creating protected areas separate from human activities, and see more and more how much potential there is outside of forests. The forests are key - we need them, of course. But in addition to that, I'm always surprised by how important how you manage a farm is for biodiversity."

"We believe the findings of our research are new to science, but in a sense, it merely confirms what Indigenous communities around the world have already known for a long time, which is that humans can and should have reciprocal relationships with the rest of the local ecological community they are part of," said Tadashi Fukami, a professor of biology in H&S and of Earth system science in the Stanford Doerr School of Sustainability and a co-author of the paper.

Incentivizing Farmers

In the 1980s and 90s, deforestation was occurring in Costa Rica at the fastest rate ever seen on a country scale. Then, they turned it around - becoming a renowned model of success. By setting up the world's first countrywide payment for ecosystem services (PES) program, Costa Rica reversed this trend: today, forests cover almost 60% of its land, up from 40% in 1987.

The country currently aims to double the amount of protected forest in just a few years. In its existing PES program, any landowner can receive money for reforesting even small parts of their land. Now, the government is also working toward a new PES program to incentivize farmers to adopt best management practices.

This study will help inform Costa Rican policymakers in understanding the benefits provided over time by different farming practices. Said Daily, "We need to recognize the vital work many farmers are doing that supports biodiversity."

Nicholas Hendershot was a postdoctoral researcher with the Center for Conservation Biology at Stanford and is now a forest ecologist with The Nature Conservancy-California. Gretchen Daily is also a senior fellow in the Stanford Woods Institute for the Environment. Other co-authors on the paper are Alejandra Echeverri, a senior scientist at the Natural Capital Project, Luke Frishkoff of the University of Texas at Arlington, and prominent Costa Rican ornithologist Jim Zook.

Hendershot's work was supported by the Gerhard Casper and John P. Morgridge Stanford Graduate Fellowship, the OTS Emerging Challenges in Tropical Science Fellowship, and the Winslow Foundation. Funding for data collection from 1999-2017 was generously provided to Daily by the LuEsther T. Mertz Charitable Trust, the Moore Family Foundation, and the Winslow Foundation.

Frequently Asked Questions

NOTE: Researched FAQs by Disabled World (DW)

Why are birds important to farms?

Birds eat large numbers of insects that damage crops, help pollinate some plants and spread seeds, which can reduce the need for pesticides.

What is a payment for ecosystem services program?

It is a scheme that pays landowners to manage their land in ways that provide public benefits, such as clean water, carbon storage or wildlife habitat.

Does diversified farming produce less food?

Not necessarily. The researchers note that diversified farms are not always lower yielding than intensive farms, and they can be more resilient over time.

What is food security?

Food security means all people at all times have physical and economic access to enough safe, nutritious food to meet their needs for an active and healthy life.

Why are bird populations used to measure ecosystem health?

Birds are easy to observe, respond quickly to changes in habitat and food supply, and occupy many roles in ecosystems, making them useful indicators.

What is fortress conservation?

It is an approach that protects nature by setting aside areas closed to people and farming, which critics say ignores the value of working landscapes and local communities.

How can home gardeners help birds and pollinators?

Planting native flowers, shrubs and trees, avoiding pesticides, and leaving some areas wild can provide food and shelter for birds and insects.

Can people with disabilities take part in gardening and farming?

Yes. Raised beds, adapted tools, wide paths and community garden programs make growing food accessible to many people with disabilities and seniors.

Insights, Analysis, and Developments

Editorial Note: Protected areas alone are too small and scattered to keep wildlife and the services it provides, so how farmland is managed has become central to conservation. This long-term study shows that farms with a mix of crops and patches of trees can act as both habitat and corridors, while also supporting the pest control and pollination that keep food affordable and nutritious. Paying farmers for these benefits, as Costa Rica is doing, offers a practical model, and the same principle matters for communities worldwide whose food supply depends on healthy surrounding landscapes.*

Attribution/Source(s): This peer-reviewed publication was selected for publishing by the editors of Disabled World (DW) due to its relevance to the disability community. Originally issued as a press release by Stanford University and published on 4 Sep 2023. Last updated on 4 Nov 2026. This content may have been edited for style, clarity, or brevity.

* Editorial additions by Ian C. Langtree.