Staggering declines in bird populations taking place around the world

Staggering declines in bird populations are taking place around the world, mainly due to the loss and degradation of natural habitats and direct overexploitation of many species.

• The authors reviewed changes in avian biodiversity using data from the International Union for Conservation of Nature’s “Red List” to reveal population changes among the globe’s 11 000 bird species.
• Despite their findings, study authors say there is hope for avian conservation efforts, but transformative change is needed.

This study presents an overview of the global spatiotemporal distribution of avian biodiversity, changes in our knowledge of that biodiversity, and the extent to which it is imperiled. It summarizes the threats driving changes in bird species richness and abundance, highlighting the increasingly synergistic interactions between threats such as habitat loss, climate change, and overexploitation.¹

Many metrics of avian biodiversity are exhibiting globally consistent negative trends, with the International Union for Conservation of Nature’s Red List Index showing a steady deterioration in the conservation status of the global avifauna over the past three decades.

“We are now witnessing the first signs of a new wave of extinctions of continentally distributed bird species,” said Alexander Lees, lead author of the new study published this month in the journal Annual Review of Environment and Resources.²

“Avian diversity peaks globally in the tropics and it is there that we also find the highest number of threatened species.”

The study found that approximately 48% of existing bird species worldwide are known or suspected to be undergoing population declines.

Populations are stable for 39% of species, only 6% are showing increasing population trends, and the status of 7% is still unknown.

The findings mirror the results of a groundbreaking 2019 study which determined that nearly 3 billion breeding birds have been lost during the past 50 years across the United States and Canada. The lead author of that study is also an author on this global status report.

“After documenting the loss of nearly 3 billion birds in North America alone, it was dismaying to see the same patterns of population declines and extinction occurring globally,” says conservation scientist Ken Rosenberg of the Cornell Lab, now retired. “Because birds are highly visible and sensitive indicators of environmental health, we know their loss signals a much wider loss of biodiversity and threats to human health and well-being.”

“The fate of bird populations is strongly dependent on stopping the loss and degradation of habitats,” Lees said. “That is often driven by demand for resources. We need to better consider how commodity flows can contribute to biodiversity loss and try to reduce the human footprint on the natural world.”

“Fortunately, the global network of bird conservation organizations taking part in this study have the tools to prevent further loss of bird species and abundance,” Rosenberg said. “From land protection to policies supporting sustainable resource use, all of it depends on the will of governments and of society to live side by side with nature on our shared planet.”

References:

¹ State of the World’s Birds – Alexander C. Lees et al. – Annual Review of Environment and Resources -May 4, 2022 – DOI: 10.1146/annurev-environ-112420-014642

² Global bird populations steadily decline – Cornell University – May 5, 2022

Featured image credit: Asim Bijarani