About
eBird Status and Trends Maps is a scientific platform developed by the Cornell Lab of Ornithology that provides an unprecedented fine-scale view of where bird species are increasing or decreasing across the globe. Powered by millions of bird observations submitted by citizen scientists through the eBird program, the platform uses advanced statistical modeling and machine learning to generate population trend maps for more than 850 bird species. The maps visualize cumulative changes in estimated relative abundance at a resolution of 27x27 km regions—smaller than many counties—enabling researchers and conservationists to identify precisely where declines or increases are occurring. Red circles indicate population decline, blue circles indicate increase, and the intensity of the color reflects trend strength. Circle sizes scale with estimated relative abundance, so larger, darker red circles pinpoint where a larger share of a population is declining. A standout feature is the ability to show how bird abundance changes during different life-cycle phases—breeding and non-breeding seasons—helping scientists untangle how conditions on wintering or breeding grounds affect populations. The underlying statistical methodology accounts for changing observer behavior and detection skill over time, and incorporates habitat variables to sharpen estimates. Regional and state/province summaries with 80% confidence intervals are available alongside every map. eBird Trends maps are a critical tool for global conservation planning: they expose where urgent research is needed, and highlight where conservation measures are working so those strategies can be replicated. The platform is freely accessible to researchers, educators, ornithologists, conservation organizations, and bird enthusiasts worldwide.
Key Features
- 27x27 km Fine-Scale Resolution: Population trends are mapped at a resolution smaller than most counties, enabling precise identification of where declines or increases are occurring.
- 850+ Species Coverage: Trend maps are available for over 850 bird species, including many outside the United States and Canada, powered by global citizen science contributions.
- Seasonal Life-Cycle Analysis: Maps reveal how bird abundance changes during breeding and non-breeding seasons, helping scientists distinguish drivers on wintering vs. breeding grounds.
- Statistical Rigor with Confidence Intervals: Trend estimates account for observer behavior and habitat variables, with 80% confidence intervals displayed at regional and state/province levels.
- Citizen Science Data Foundation: Maps are generated from millions of bird observations submitted by eBird citizen scientists worldwide, enabling global coverage at unprecedented scale.
Use Cases
- Conservation researchers identifying geographic hotspots of bird population decline to prioritize fieldwork and intervention efforts.
- Government agencies and environmental policymakers using trend data to designate protected areas or fund conservation programs.
- Academic ornithologists studying how breeding-ground vs. wintering-ground conditions drive species-level population changes.
- Environmental educators and university instructors using interactive trend maps to teach students about biodiversity loss and citizen science.
- Birding organizations and NGOs tracking whether conservation measures in specific regions are producing measurable population recoveries.
Pros
- Unprecedented Spatial Resolution: 27x27 km grid resolution surpasses previous population trend tools, enabling conservation actions to be targeted at county-level precision.
- Free and Publicly Accessible: The platform is freely available to anyone, from professional researchers to amateur birders, with no registration required.
- Methodologically Sound: The statistical approach corrects for observer skill drift and habitat variables, producing reliable trend estimates with transparent confidence bounds.
- Global and Multi-Species Scope: Coverage of 850+ species across multiple continents makes it one of the most comprehensive bird trend resources available.
Cons
- Dependent on Citizen Science Density: Trend estimates are less reliable in regions with sparse eBird observation coverage, limiting global utility in under-observed areas.
- Web-Only Access: The platform is exclusively browser-based with no mobile app or offline mode, restricting use in the field.
- No Raw Data Export: Users cannot directly download underlying trend data from the map interface; bulk data access requires separate eBird data requests.
Frequently Asked Questions
What do the colors on eBird Trends maps represent?
Blue circles indicate an increase in bird abundance, red circles indicate a decline, and white circles represent locations where the trend is not statistically significant. The darker the color, the stronger the trend.
How many species are covered by eBird Trends maps?
Trends maps are currently available for more than 850 bird species, including many species outside the United States and Canada.
How is the underlying data collected?
The maps are powered by bird observations submitted by citizen scientists through the eBird program, managed by the Cornell Lab of Ornithology. Data scientists then apply advanced statistical models to these observations.
What time period do the trends cover?
Trend maps show cumulative percent change in population size over a specified multi-year period (e.g., 2012–2022 for some species), not annual fluctuations.
Is eBird Trends free to use?
Yes, eBird Status and Trends Maps is entirely free and publicly accessible. No login or subscription is required to explore the trend maps.
