Migratory Birds that Fly between Canada and South America Face Highest Risk, per New Audubon Study
Audubon scientists developed a new framework to understand threats to migratory species and found that birds traversing the longest distances across the Americas are at highest risk, underscoring the need for coordinated hemispheric conservation efforts.
NEW YORK (February 17, 2025)-- Today, scientists with the National Audubon Society published research in Nature Ecology & Evolution that will help inform global efforts to protect migratory birds. In the study, Multispecies migratory connectivity indicates hemispheric-scale risk to bird populations from global change, researchers propose a new way to measure risk and identify where conservation efforts are most needed for species that travel between specific breeding and non-breeding regions across North, Central, and South America, and the Caribbean.
“There is still so much to understand about how migratory birds will fare under global change across the Americas,” said Dr. Sarah Saunders, Audubon’s senior manager of quantitative science and lead author of the study. "Migratory birds rely on a network of habitats across continents, and our findings highlight where conservation efforts are most needed to ensure their persistence."
The study integrates movement data from more than 329,000 birds of 112 species, generously shared with Audubon by dozens of data contributors, to identify the areas where migratory birds face the greatest threats from climate change and habitat loss. Researchers introduce a new metric, multispecies migratory connectivity, to quantify exposure to global change. Despite a growing understanding of migratory connectivity – the linking of bird populations across different regions and seasons – for individual species, the study developed a new metric to combine connectivity patterns across many species. By synthesizing this metric (exposure) with projected climate and land-cover changes (hazard) and conservation status (vulnerability), researchers identify the geographic connections at the highest risk throughout the Western Hemisphere.
The findings show that connections between some breeding regions in Canada and non-breeding regions in South America are particularly vulnerable, emphasizing the risks faced by long-distance migrants like Common Terns and Blackpoll Warblers. Alarmingly, over half of the geographic connections at very high risk involve breeding regions in the eastern United States.
The study also found that multispecies migratory connectivity was the greatest predictor of risk for bird population declines, stressing the importance of international collaboration to ensure that birds are protected across their full annual cycle.
“Bird migration is one of the most incredible and impressive phenomena in nature,” said Dr. Jill Deppe, senior director of Audubon’s Migratory Bird Initiative. “Migratory birds tell us they need our help, and this new science highlights the need for continued investment and international efforts to reduce the hazards migratory birds encounter across the entire hemisphere.”
Migratory birds are in particular need of conservation action. A 2019 study determined that there are nearly three billion fewer birds in North America than in the year 1970, with two-and-a-half billion of those birds considered migratory. More information about migratory birds and their journeys can be found using the Bird Migration Explorer tool.
The survival of many of these migratory species remains uncertain if countries do not take action to reduce climate pollution and the impacts of human activities that threaten birds and their habitats. By learning more about the threats these birds are facing during their annual cycle, we can focus on the places and actions that will have the biggest impact for securing their future.
A public link for the study can be found at: https://rdcu.be/eabgN
About Audubon: The National Audubon Society is a leading nonprofit conservation organization with 120 years of science-based, community-driven impact, dedicated to protecting birds and the places they need, today and tomorrow. Birds are powerful indicators of our planet’s health, acting as sentinels that warn us of environmental change and inspire action. Audubon works across the Western Hemisphere, driven by the understanding that what is good for birds is good for the planet. Through a collaborative, bipartisan approach across habitats, borders, and the political spectrum, Audubon drives meaningful and lasting conservation outcomes. With 800 staff and over 1.9 million supporters, Audubon is a dynamic and ever-growing force committed to ensuring a better planet for both birds and people for generations to come. Learn more at www.audubon.org and on Facebook, Twitter and Instagram @audubonsociety
Media Contact:
Robyn Shepherd, Communications Director, Advocacy robyn.shepherd@audubon.org
Nicolas Gonzalez, Senior Manager for Science Communications, nicolas.gonzalez@audubon.org.