Mission: Citizen Science

How You Can Help

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Citizen Science

Each day, bird watchers report tens of thousands of bird observations to citizen-science projects at the Cornell Lab of Ornithology, contributing to the world’s most dynamic and powerful source of information on birds. The Cornell Lab has been at the forefront of citizen science since 1966, and continues to innovate by creating online tools enabling people to share and explore their data. Today, the birding community taps into millions of records to see how their own sightings fit into the continental picture, and scientists analyze the data to reveal striking changes in the movements, distributions, and numbers of birds through time.

More than 400,000 people contribute to the Cornell Lab’s citizen-science projects each year, gathering data on a vast scale once unimaginable. Scientists use these data to determine how birds are affected by habitat loss, pollution, and disease. They trace bird migration and document long-term changes in bird numbers continentwide. The results have been used to create management guidelines for birds, investigate the effects of acid rain and climate change, and advocate for the protection of declining species.

If you enjoy watching birds, we need your help, whether you are a beginner or a seasoned birder. Participating can take as little or as much time as you want—you decide! We invite you to be a part of our community and get started with a citizen-science project today.

Project Highlights

Projects at a Glance

We offer an array of fun and meaningful citizen-science projects enabling people to observe birds at their favorite locations and share their information with scientists and with each other.


eBird offers innovative online tools for birders to keep track of their own lists and contribute their bird sightings for use in science and conservation. Birders, scientists, and conservationists can collect, manage, and store their observations in eBird’s globally accessible database—or use graphing, mapping, and analysis tools to better understand patterns of bird occurrence and the environmental and human factors that influence them. This real-time data resource produces millions of observations per year from across the hemisphere. eBird is a joint project of the Cornell Lab of Ornithology and National Audubon Society.

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Project FeederWatch

Each year, 15,000 people count birds at their feeders for Project FeederWatch. With more than 1.5 million checklists submitted since 1987, FeederWatchers have contributed valuable data enabling scientists to monitor changes in the distribution and abundance of birds. Using FeederWatch data, scientists have studied the influence of nonnative species on native bird communities, examined the association between birds and habitats, and tracked unpredictable movements in winter bird populations. Participants gain from the rewarding experience of watching birds at their feeders and contributing their own observations to reveal larger patterns in bird populations across the continent.

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By finding and monitoring bird nests, NestWatch participants help scientists track the breeding success of birds across North America. Participants witness fascinating behaviors of birds at the nest and collect information on the location, habitat, bird species, number of eggs, and number of young. Scientists use these data to track the reproductive success of North American breeding birds across the continent. Launched in 2007 with funding from the National Science Foundation, NestWatch has collected more than 150,000 nesting records. Combined with historic data, this information will help scientists address how birds are affected by large-scale changes such as global climate change, urbanization, and land use.

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Celebrate Urban Birds

Celebrate Urban Birds is a bilingual project focused on engaging underserved urban and rural residents in science, environmental education, and community activities related to birds. Participants observe a small, defined bird-watching area for 10 minutes and report on the presence or absence of 16 species of birds. The project assesses the value of green spaces for birds, ranging in size from a potted plant to half a basketball court. Launched in 2007, Celebrate Urban Birds has partnered with more than 10,000 community organizations and distributed more than 300,000 educational kits in English and Spanish. The project offers mini-grants once a year to support community events involving birds, habitat improvement, and the arts. Seasonal Challenges, including the annual Funky Nests in Funky Places Challenge, offer participants opportunities to share their photos, art, videos, stories, and poems, and win prizes.

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Great Backyard Bird Count

Begun in 1998, the four-day Great Backyard Bird Count was the first citizen-science program to collect and display bird observation data online on a large scale. Today, the Great Backyard Bird Count is one of the most popular annual events among bird watchers. It has been merged with the eBird online checklist program to make the information gathered even more useful to science and to allow people to take part anywhere in the world with an Internet connection. The Great Backyard Bird Count is a joint project of the Cornell Lab of Ornithology and National Audubon Society with Canadian partner Bird Studies Canada.

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The YardMap Network is an NSF-funded project that builds online communities to investigate the impacts of bird-friendly and carbon-neutral practices in backyards, community gardens, and parks. Participants will locate their yards or parks on a Google maps interface, then document their sustainable practices using simple point n’ click digital tools to create data maps. People document practices such as adding native plants, putting up bird feeders, installing a solar panel, or reducing lawn size. By providing access to rich media resources for learning about sustainable practices and enabling people share their maps and practices with each other, YardMap strives to create online conservation communities engaged in real life sustainable practices. The YardMap Network works closely with with the National Audubon Society, U.S. Fish and Wildlife Service, Roger Tory Peterson Institute, Empire State College’s online alumni program, and the American Community Gardening Association, as well as a team of advisors including Doug Tallamy, Steve Kress, Justin Dillon, and Simon St. Laurent.

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Citizen-Science Results

Citizen-science participants collect data on continentwide scales through time, enabling scientists to improve the scientific understand and conservation of birds. Below, we highlight some of the major findings.

Birds and Habitat Fragmentation

Fragmented landscapes, in which natural habitat exists as isolated patches, are a common side-effect of human activities. We study the effects of fragmentation with the help of citizen-science participants. Our Birds in Forested Landscapes project involved volunteer birders at 3,800 sites across North America. The project yielded valuable insights about habitat fragmentation and factors such as occupancy by birds and local extinction rates. Results were published in scientific journals including the Journal of Animal Ecology, the Proceedings of the National Academy of Sciences, and Ecology and Society. The results have also been compiled into guidelines for land managers interested in conservation of tanagers, forest thrushes, and Golden-winged Warblers.

Effects of Acid Rain and Mercury on Birds

Led by scientist Stefan Hames, we are studying the biochemical pathways by which acid rain and mercury deposition reduce the availability of calcium, an important nutrient for nesting birds and their eggs. Data collected by participants in the Birds in Forested Landscapes citizen-science project indicated that Wood Thrushes are less likely to breed at sites heavily impacted by acid rain; the absence of high-calcium prey may be the cause. Further pollution research focuses on mercury contamination in birds, a condition that is surprisingly pervasive in upland habitats, particularly in combination with acid rain. With support from the Leon Levy Foundation, our researchers are developing a model of mercury contamination in New York forests and identifying regions and birds at high risk, including Wood Thrushes and Red-eyed Vireos.

Birds and Climate Change

Climate has an enormous influence on where birds survive and reproduce. In the short term, weather can influence the timing of migration, territory establishment, breeding, and egg laying. Over the long term, species have adapted to seasonal weather trends. As global climate patterns change, many harbingers of spring are occurring earlier each year. We combine data from citizen-science projects with long-term data on weather to examine climate's role in the changes we are seeing in the ranges of some bird species, as well as the timing and outcomes of breeding.

Citizen-Science Research on Bird Diversity, Distribution, and Abundance

Understanding changes in the distribution and abundance of populations is difficult because birds are so mobile and most species are widely distributed. In addition, fluctuations in food supplies or other changes in resources can cause local fluctuations that may not reflect broader patterns. Are populations really changing, or have the birds simply moved elsewhere? What effect do invasive, nonnative birds have on native bird communities? Do birds move in predictable patterns? These questions can only be answered by gathering observations across large spatial scales over long periods of time. Citizen-science programs such as Project FeederWatch are invaluable for collecting consistent information at spatial and temporal scales necessary to answer these questions. Using a hypothesis-testing approach to explore questions of importance to bird conservation, citizen-science researchers use long-term data, cross-validation with other surveys, and modern statistical approaches to detect patterns, investigate mechanisms, and understand changes.

Breeding Ecology and Conservation of the Common Nighthawk

The Common Nighthawk is a Neotropical migrant that breeds across North America. Although nighthawks are still locally common in some areas, they appear to be declining across their range, especially in urban and suburban areas. Unfortunately, nighthawk populations are difficult to census using traditional methods, so it has been difficult to assess changes in abundance over time. Cornell graduate student Rebecca Lohnes and Brett Sandercock at Kansas State University have developed a method enabling citizen-science participants across North America to monitor breeding populations of nighthawks. In addition, Rebecca has studied the breeding ecology of common nighthawks at the Konza Prairie Biological Field Station, Kansas, examining the influence of nest location, adult and chick behavior, and nest microclimate on nest success. She hopes that information about nest site characteristics of a relatively robust population of birds in native prairie will help to inform urban restoration efforts.

Cerulean Warbler Atlas Project

Cerulean Warbler Atlas Project mapped breeding populations of Cerulean Warblers from 1997 to 2000 and identified critical sites and habitats in each state and province. This information formed the basis for a rangewide conservation plan developed through U.S. Fish and Wildlife Service. We continue to work with the Cerulean Warbler Technical Group, including the international El Grupo Ceruleo, which received a U.S. Forest Service International Cooperation Wings Across America award.

House Finch Eye Disease

In the winter of 1993–1994, people in the Washington, D.C., area began seeing House Finches at their bird feeders with a strange new disease. The area around the finches’ eyes was red and swollen, and in some cases the birds had become blind. The cause of the disease was identified as a common bacterial pathogen of domestic poultry. The bacteria had unexpectedly mutated and jumped to House Finches. Within three years, roughly 60% of House Finches in eastern North America were dead. The disease has persisted since then, and House Finch numbers have yet to recover completely. Bird Population Studies researchers developed a citizen-science monitoring program called the House Finch Disease Survey to document the spread of the disease and used additional citizen-science data to describe its impacts. Further work investigated why the pathogen has been so successful and the disease so persistent. The goal is to gain a better understanding of the ecology of other diseases in other organisms, including humans. This work involves close collaboration with researchers at five universities.

Data Analysis Toolkits and the Avian Knowledge Network

Using new techniques to analyze millions of data records, we study how bird distribution and abundance change through time and geographical space. We start by identifying large-scale patterns. This seemingly basic task is challenging because bird observations are unevenly distributed across the continent and are influenced by observers’ ability to detect birds. In collaboration with statistical and computer scientists, our researchers are developing novel methods to analyze data collected by both ornithologists and citizen-science participants around the world. The Cornell Lab is leading an initiative to digitally archive tens of millions of data records through the Avian Knowledge Network and to make these data more widely available. This will enable scientists to create a clearer picture of where bird species live and how their distributions change.

West Nile Virus

When West Nile virus arrived in North America in 1999, scientists began to document the sharp declines it caused in American Crow populations. Deaths of smaller, less common birds have been more difficult to detect; details of which species are affected, and how severely, are still not well known. We are analyzing data from citizen-science databases, including the Christmas Bird Count, North American Breeding Bird Survey, and Project FeederWatch. Our goals include understanding which bird species have been affected by West Nile virus, whether ecological factors such as bird species diversity have altered the virus's effects across the continent, and whether populations of affected birds are recovering.

Citizen-Science Technology

We develop interactive online tools to engage hundreds of thousands of people in contributing bird observations and exploring the results.


eBird offers innovative online tools for birders to keep track of their own lists and contribute their bird sightings for use in science and conservation. Birders, scientists, and conservationists can collect, manage, and store their observations in eBird’s globally accessible database—or use graphing, mapping, and analysis tools to better understand patterns of bird occurrence and the environmental and human factors that influence them. This real-time data resource produces millions of observations per year from across the hemisphere. eBird is a joint project of the Cornell Lab of Ornithology and National Audubon Society.

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Breeding Bird Atlases Online

breeding bird atlas pageWe create Internet tools enabling Breeding Bird Atlases to collect and display data online. Atlases bring volunteer bird watchers and ornithologists together to find as many breeding bird species as possible in intensively sampled areas throughout a region. Atlases provide valuable information that can be used to set conservation priorities, including designation of protected areas, and can help monitor the outcomes of conservation management actions. See examples of online Breeding Bird Atlases.

eBird APIs

BirdsEye applicationWe create APIs (application programming interfaces) enabling websites and products to use bird observation data from eBird. For example, birders can access real-time data in eBird to quickly find out where birds are being reported and get a map with directions, using the BirdsEye app for iPhone® and iPod touch.

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eBird Trail Tracker

The eBird Trail Tracker kiosk is a useful addtion to wildlife refuges, nature centers, and birding trails. On its interactive display, visitors can see which birds are being reported, contribute their own observations, and enjoy photos, sounds, and life history information. The observations become part of the eBird database, which stores and displays data from across the Western Hemisphere.

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