ECCC Scientists Partner on Major Study on Bird Losses in North America

ECCC scientists Adam Smith and Paul Smith, and scientist emeritus Peter Blancher coauthored a groundbreaking study published earlier this month in the journal Science, entitled “The Decline of the North American Avifauna”. The scientists collaborated with researchers from Cornell University, the American Bird Conservancy and several other organizations on the study. The paper outlines an alarming net loss of nearly three billion birds, a 29% decline across North America since 1970. The results complement the findings in The State of Canada’s Birds report, released in June 2019.

The study shows that the overall number of birds has declined across almost all major biomes, including grasslands, boreal and temperate forests, and the Arctic (Figure 1). Declines in many common backyard birds, such as White-throated Sparrows and Dark-eyed Juncos contribute to these staggering losses. Species that have been relocated by humans to a new environment, such as the House Sparrow, have also declined.

The major cause of bird declines is loss of habitat, especially due to agricultural intensification and urbanization. Other factors include domestic cats acting as predators, collisions with glass, and a decline in insects – an important food source for many bird species – which may be linked to pesticide use across North America.

Scientists previously hypothesized that increases in some species offset declines in others. However, this new research shows that the number of birds in North America has dropped dramatically – we have lost more than 1 in 4 birds since the 1970s.

The Hopeful News

The research does show some positive developments. Conservation efforts have led to increased numbers of waterfowl, such as ducks, geese and swans.

Endangered species legislation and the banning of DDT have also resulted in a comeback of certain species, including the bald eagle.

These conservation successes provide a roadmap for ways to reverse population declines. The international cooperation that has helped waterfowl populations rebound through wetland conservation could serve as a model for protection of grasslands and critical migratory stopover sites for shorebirds.

The study has raised the department’s profile and brought new attention to migratory bird conservation. The article was in the top 5% of all research outputs scored by Altmetric (measures of how often journal articles and other scholarly outputs like datasets are discussed and used around the world). The extensive media coverage the article received has allowed more Canadians to become aware of the work of two of our ECCC scientists.

What Can You Do?

You can take action today to reverse the decline of North American birds!

By making the windows on our homes and businesses more visible to birds, we can save millions of birds each year. Keeping cats and wildlife apart has an even greater impact, saving the lives of hundreds of millions of birds each year. Avoiding the use of single-use plastic and reducing food waste protects the quality of water, air and land for both birds and people alike.

The Time to Act is Now

“Our results signal an urgent need to address the ongoing threats of habitat loss, agricultural intensification, coastal disturbance, and direct anthropogenic mortality (deaths caused by humans), all exacerbated by climate change, to avert continued biodiversity loss and potential collapse of the continental avifauna,” the paper states.

“What our birds need now is an historic, hemispheric effort that unites people and organizations with one common goal: bringing our birds back” says ECCC scientist, Adam Smith.

You can read the full paper in Science here, and explore videos, more information, ideas for individual action, and other content related to the paper here.

Figure 1

Figure 1

Figure 1

Net Population Change in North American Birds

  • By integrating population size estimates and trajectories for 529 species, we show a net loss of 2.9 billion breeding birds across the continental avifauna since 1970, Gray shading represents +/- credible intervals around total estimated loss. Map shows colour-coded breeding biomes based on Bird Conservation Regions and land cover classification.
  • Net loss of abundance occurred across all major breeding biomes except wetlands.
  • Proportional net population change relative to 1970, +/- 95% confidence interval.
  • Proportion of species declining in each biome.


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