Bird sightings from eBirders cover 84% of the globe

By Kathi Borgmann October 28, 2019
Brassy-breasted Tanager Tangara desmaresti

Finding birds, tallying your life list, and discovering new places to bird are all now just a few clicks away thanks to eBird, the world’s largest biodiversity citizen-science project. But eBird has also transformed what we know about the birds around us—from revealing unique loop migrations of Rufous Hummingbirds to identifying high concentrations of Scissor-tailed Flycatchers along the Pacific coast of Central America during the winter, observations submitted by bird watchers have advanced science and conservation beyond expectations.

Since eBird’s inception in 2002, Bird watchers around the world have submitted eBird checklists from Papua New Guinea to Greenland, resulting in more than half a billion observations. A new paper out in the journal Ecography led by Frank La Sorte, a Research Associate at the Cornell Lab of Ornithology, in collaboration with Marius Somveille at Birdlife International in the UK, found that bird occurrence information from eBird is available for 84% of the land surface on earth! La Sorte says, “I was surprised by the findings considering that the majority of eBird data is centered within the contiguous US.”

Observations submitted to eBird per day at three different spatial scales. See Figure 3 for more details. 

But not all areas across the globe had equal coverage, says La Sorte. When the team examined each month of the year, observations submitted to eBird captured around three quarters of the bird species that occur in each region. Zooming in even more to smaller sized patches of land about the size of South Dakota and at observations of birds submitted per day, La Sorte and Somveille found that only around 5% of the earth’s terrestrial surface contained enough observations of all of the species present in the region to be considered complete. This means that to better understand bird populations, more observations are needed in poorly sampled regions of the globe. “Birding under-birded areas can have a demonstrable impact on what we know about bird abundance” says Chris Wood, eBird Lead.

La Sorte and Somveille’s study also highlights the need to go birding year-round. They found a greater concentration of eBird records during spring migration in North America, which is when most people go out birding. It is important to report your observations year-round to obtain finer-resolution data that can help scientists better understand how bird populations move across space and time, says La Sorte.

Regions with the best coverage include North America, Europe, India, Australia, and New Zealand coinciding with active birding communities. But La Sorte emphasizes “that these regions should be surveyed at similar or higher levels into the future to support long-term and robust monitoring of bird populations.”

In areas with fewer eBird records such as South America, Africa, and northern Asia, Wood, suggests “when traveling don’t just go to the most famous trails in the best national parks— explore. Expand your concept of where to enter a checklist. That five-minute stop for gas, you may as well do an eBird checklist.” “Ideally,” La Sorte says, “we want occurrence information across the full annual cycle within all regions of the earth.”

Understanding where in the world bird data is common or scarce can help researchers build better tools to inform conservation actions, from site-specific information about the occurrence and abundance of birds, to looking at patterns of species abundance across continent-spanning flyways.


Read the paper

La Sort, F. A., and M. Somveille. (2019). Survey completeness of a global citizen-science database of bird occurrence. Ecography