Including Bird Data Improves Estimates of Wild Bee Species

A new study published today in the journal PLOS One reveals that combining bird observation data with land cover information provides more accurate predictions of numbers of wild bee species—a metric called richness—than using either dataset alone. This finding could help guide conservation efforts for wild bees, which are experiencing widespread population declines despite the crucial role they play in ecosystem health and agriculture production. Wild bees are different from honeybees, which are raised by amateur and commercial beekeepers for honey and crop pollination.

The study, led by a team of scientists at the Cornell Lab of Ornithology and the Cornell Atkinson Center for Sustainability, sought to fill the gap in our understanding of the richness of wild bees across the United States. “Our understanding of where bees occur is really hampered by insufficient data, and that limits conservation planning,” said Josée Rousseau, lead author and postdoctoral researcher at the Cornell Lab of Ornithology. 

To fill in the data gaps of bee populations, the team turned to bird data from the Cornell Lab of Ornithology’s eBird program, a database of bird observations submitted by birdwatchers. “Birds can be excellent ecological indicators, often telling us more about environmental quality than satellite data. And thanks to eBird participants, we had an opportunity to see if birds could tell us something about wild bees,” said Amanda Rodewald, faculty director of the Center for Avian Population Studies at the Cornell Lab of Ornithology. 

The team combined bird data from eBird with publicly available data on land cover across the eastern and central United States to predict the number of wild bee species, initially using bee data from field surveys compiled in the Global Biodiversity Information Facility and Symbiota Collections of Arthropods Network. They examined 476,584 bee records, representing 792 species of wild bees alongside bird data from 79 species, and landcover data from the United States Department of agriculture. Their innovative approach demonstrated that the combination of bird and environmental data was more effective at predicting wild bee richness across broad geographic areas.

“Until now, most efforts to predict bee populations have relied solely on land cover data,” said Rousseau. “By incorporating bird data, we’ve developed a more nuanced understanding of the kinds of landscapes where we might expect higher bee richness, and that understanding can aid conservation planning.” 

“Birds and bees often respond similarly to habitat features and alterations, though at different scales,” Rodewald explained. “Birds can indicate aspects of the environment that might not be visible in satellite imagery alone, such as the presence of flowering plants or specific management practices.”

For example, Gray Catbirds, which often eat fruit from trees and shrubs in the understory, can indicate the existence of flowering trees and shrubs that are important for bees. And Orchard Orioles can signal the presence of open woodland and orchards which provide habitat to a large number of wild bee species. 

The study also found that bee species richness was generally higher along the East Coast and Appalachian Mountains and lower in Midwestern agricultural regions dominated by monocultures of corn and alfalfa. “These findings,” said Rousseau, “mean we may need different conservation strategies in different regions. For example in areas with higher bee richness like the Appalachians the focus should be on protecting habitats that are doing a good job supporting bees but in areas with intensive agricultural crops, conservation should focus on habitat restoration to recover bee populations.”

The implications of this research extend far beyond academic interest,” explained Patrick Beary, senior director of Strategic Partnerships at Cornell Atkinson. “We’ve been approached by conservation organizations looking to maximize their impact, communities concerned about their local ecosystems, and companies with sustainability commitments who all need better data to guide their pollinator initiatives. This tool helps answer two critical questions they all share: where should we focus our efforts to boost pollinator abundance, and do our interventions improve conditions for bees within landscapes?”

This study was funded by the Walmart Foundation. The findings, conclusions, and recommendations presented in it are those of the authors alone, and do not necessarily reflect the opinions of the Walmart Foundation.

Reference: Rousseau J S, Johnston A and Rodewald AR. Indicators of a data-deficient taxa: combining bird and environmental data enhances predictive accuracy of wild bee richness. PLOS One. 2025. doi: 10.1371/journal.pone.0321496