More than one in five species of pollinators native to Canada and the United States are at risk of extinction, a new study suggests.
Nearly 23 percent of vertebrate and insect pollinators native to mainland North America, north of Mexico, have an “elevated” risk of extinction, according to a report published in the Proceedings of the National Academy of Sciences journal on March 24.
Factors behind the increased risk include land use changes, the proliferation of invasive plant species, pesticide exposure, climate change, disease, and modifications to hydrological and fire regimes.
“Pollinators are critical to maintaining terrestrial ecosystem function and the global food supply, but many are in decline,” reads the study.
“We assessed the extinction risk of nearly 1,600 species of vertebrate and insect pollinators and found that more than one in five species is at risk of extinction.”
The study assessed 1,579 species of the most widely studied pollinator groups. It was co-authored by 15 field experts, including Canadian zoologist John Klymko of the Atlantic Canada Conservation Data Centre.
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Bees are the most at-risk insect group, the study found, with nearly 35 percent of 472 species classified as such. Meanwhile, almost 20 percent of butterfly species and 16 percent of moth species are also facing risks.
Of the species examined, 10 bee, 11 butterfly, and two moth species were classified as “critically imperiled.”
The report identifies leafcutter and digger bees as the two most threatened bee species, with nearly half of their population at risk. However, compared to some non-pollinator animals, bees face less risk than freshwater and terrestrial mollusks, for example.
Other pollinator insects face slightly lower risks, such as flower flies, at nearly 15 percent, and beetles at 12.5 percent. All three bat species assessed are at risk of extinction, while none of the 17 hummingbird species examined are.
The report notes that pollinating insects contribute more than $15 billion annually in value to North American agriculture, and that along with nectar-feeding bats and hummingbirds, they are key to the ecosystem.
Nearly all of the 1,600 assessed pollinators, except for 19, are found in the United States, where the at-risk percentage matches the overall North American trend. In Canada, the at-risk percentage is lower, at 10.2 percent, since only 759 of the examined species include Canada in their ranges.
California was the jurisdiction with the highest pollinator diversity, with 678 species, followed by Arizona and Texas. In Canada, the province with the highest pollinator diversity was British Columbia, with 487 species.
At-risk pollinator species were most likely to be found in woodland, grassland, and shrubland or chaparral habitats, according to the study. They were least likely to inhabit forests or alpine or tundra habitats.
Threats to pollinators varied by region. Agriculture and climate change were the main factors in the Rocky Mountains and Great Plains, while climate change was the biggest threat in northern and western North America, says the report. In the eastern United States, pollution, urban development, and agriculture posed the greatest risks.
This study is the “largest, most taxonomically diverse” study of pollinators in Canada and the United States to date, including two vertebrate classes and four insect orders, said the authors.
Assessments occurred between 2013 and 2025.
