From Chirps to Insights: Measuring Biodiversity with Audubon’s Bird-Friendliness Index

In a world grappling with biodiversity loss and climate change, the need for practical tools to measure nature’s health has never been more urgent. That’s where birds come in—and why Audubon’s Bird-Friendliness Index (BFI) is gaining traction across the Western Hemisphere. This metric measures the abundance, diversity, and resilience of bird communities to reveal habitat health and track biodiversity gains over time. 

Birds enchant us, but they also enlighten us. They are powerful indicators of ecosystem health. Their presence—and the diversity of bird species present and roles they play in the community—can tell us a lot about the state of nature. Audubon’s Bird-Friendliness Index builds on this idea, offering a scientifically rigorous yet practical way to measure biodiversity through bird community data. 

Why Birds? 

Birds are charismatic, widespread, and sensitive to environmental change. They’re found in nearly every ecosystem on Earth and are relatively easy to detect by sight and sound. That makes them ideal candidates for monitoring biodiversity.  

Audubon’s CROWS framework captures this perfectly: birds are Charismatic, Representative, Observable, Widespread, and Sensitive & Specialized. 

Every bird sighting and every chip, chirp, and hoot is a valuable data point. The Bird-Friendliness Index uses bird observation and acoustic monitoring data to assess the diversity and health of bird communities—providing a window into the broader biodiversity of a landscape. 

But the BFI goes further than simply counting birds or tracking the presence of a single threatened species. It offers a composite view of habitat health based on bird functional diversity—not just how many birds are present, but how the range of species, with different diets, behaviors, habitat needs, and thus ways they impact their community, reflects the richness and resilience of the ecosystem. In short, a high BFI score means a habitat is supporting a wide variety of birds, which in turn signals a healthy, biodiverse environment. 

Practical, Scalable, and Accessible  

One of the BFI’s greatest strengths is its scalability. It can be applied across diverse habitats—from mangroves and marshes to forests and ranchlands—and across geographies, from the U.S. Great Plains to the cloud forests of Colombia. It’s also cost-effective, thanks to the use of low-cost autonomous recording units (ARUs) that capture the natural soundscape. These sound recordings are analyzed using artificial intelligence, allowing researchers to analyze species trends and to calculate the BFI. 

This approach—known as passive acoustic monitoring—makes biodiversity monitoring more accessible, especially in remote areas. It also enables community-based conservation, where local communities help collect and interpret data, strengthening conservation outcomes and local capacity. It also allows data to be collected without specialized knowledge, making this approach accessible to diverse groups – for example, ranchers wishing to better understand their lands or companies hoping to assess the impact of land management decisions on biodiversity.  

Harnessing AI for Greater Impact 

Audubon’s innovative use of the BFI and acoustic monitoring was recently recognized by the Bezos Earth Fund, which awarded Audubon $2 million through its AI for Climate and Nature Grand Challenge. This support will help scale the use of AI-powered acoustic monitoring across Latin America, particularly through the Conserva Aves initiative, which aims to protect over two million hectares of bird habitat by 2028. 

 Providing Audubon and its partners with advanced AI tools will enable the people managing some of the world’s most important ecosystems to better understand biodiversity trends. These insights can then help strengthen conservation across the Americas. 

A Tool That Works Across Habitats and Borders 

Since its publication in the journal Diversity and Distributions in 2020, the Bird-Friendliness Index has been applied across millions of acres. Through this experience, Audubon has identified three primary use cases for the BFI: 

• Setting Baselines: Understanding the state of nature in priority locations. 
• Comparing Sites: Evaluating biodiversity across different geographies. 
• Measuring Impact Over Time: Tracking biodiversity uplift from climate mitigation, water stewardship, or land restoration projects. 

For example, in Panama’s mangroves, data from low-cost acoustic monitoring devices helped establish a biodiversity baseline and revealed a correlation between aboveground carbon and the BFI. In the Great Lakes, BFI scores showed restored wetlands were significantly more bird-friendly than unrestored ones. On cattle ranches integrating silvopasture practices in the Cauca Valley of Colombia, the BFI increased as forest and forage cover increased​. And on Audubon Certified Bird-Friendly Land in the U.S., BFI scores increased by 8% annually and by 76% over an 8-year period—a testament to the biodiversity benefits of improved land management. 

Measuring What Matters: Turning Data Into Insights 

The BFI isn’t just a tool for scientists—it’s a powerful resource for anyone working to restore nature, mitigate climate change, or invest in sustainable outcomes. That includes: 

• Conservation organizations and project developers, who can use the BFI to prioritize sites and monitor biodiversity gains. 
• Companies, who can integrate the BFI into nature-related projects to demonstrate and disclose measurable progress toward nature goals, and the biodiversity co-benefits of climate action. 
• Financial institutions, including investors and development banks, who can use BFI data to assess nature-related opportunities, track performance of green investments, monitor for unintended adverse effects of investments, and help assess safeguard compliance. 
• Philanthropic organizations, who can support projects with clear biodiversity outcomes. 

The Bird-Friendliness Index is more than a metric—it’s a movement toward smarter, scalable biodiversity monitoring. And it’s helping partners across sectors make informed decisions that benefit birds, ecosystems, and communities.