A third of North America’s bird population could be wiped out: study

A new report on the state of North America’s bird population finds that more than one-third of bird species are under high risk of extinction unless governments take immediate action to avert the crisis.

Called the first-ever conservation assessment for all of North America’s 1,154 native bird species, the report is a joint effort of experts from Canada, the United States and Mexico under the umbrella of the North American Bird Conservation Initiative (NABCI).

While birds of the vast boreal forest across Canada and the northern U.S. are faring well, ocean bird species, coastal populations as well as birds of the tropical and subtropical forests are all in danger and require urgent conservation measures to combat the trend.

“More than half of species from oceans and tropical forests are on the Watch List because of small and declining populations, small ranges, and severe threats to their habitats,” says the report.

Seabird populations have declined upwards of 70 per cent since the 1950s due to a range of factors including disruption of island nesting sites, plastics and pollution in the oceans and overfishing of species crucial to seabird survival. The NABCI urges that marine protected areas need to be expanded to encourage population regrowth. “Our oceans are highly stressed,” says the report.

Birds of Mexico’s tropical forests are just as threatened, with more than 70 per cent of their habitat already lost to deforestation. 20 per cent of birds from the boreal forest spend their winters in the tropical forest ecosystem extending down through Central America.

While many populations are in decline, two notable exceptions -waterfowl such as ducks and geese and raptors like the peregrine falcon- are seeing their populations expand. The difference, according to the report’s authors, has been that these groups have benefited from effective conservation practices.

“We spent money and changed policies and these birds have recovered,” says Steven Price of Bird Studies Canada, a collaborator on the report. More than 350 bird species are truly tri-national, living in all three countries over the course of the year. And thus, conservation solutions need international collaboration. “Birds connect the continent,” says the report.

And while the report lists climate change as a contributing factor to population declines, a recent study from Durham University in the United Kingdom finds conclusive proof that the warming planet is having very similar large-scale impacts on bird populations in widely separated parts of the world.

Researchers gathered data over a 30 year period for 145 common bird species in Europe and another 380 in the U.S. and found similar patterns in terms of population spread and decline. The American robin in the U.S. has declined in southern states such as Mississippi and Louisiana but has increased across north-central states like the Dakotas, for example, while in Europe the Dartford warbler has increased eight-fold in population since the 1980s in the U.K. at the same time that its numbers have decreased in Spain.

The study’s authors argue that these similarities in population growth and decline have climate change as a common cause. Dr. Philip Stephens of Durham’s School of Biological and Biomedical Sciences says, “If there was no impact of climate change, you would expect the average population trend of species in the two groups to be the same, but the differences expose the fact that recent climate change has already favoured one set of species over another.”

The study was published in the journal Science.

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