Eastern meadowlark. Photo by Flickr user CheepShot.
Here in the Northern Hemisphere, we’re approaching the season when birds migrate south. But if you’ve noticed fewer birds in your backyard recently, it may not be because they took off early.
In a study published in the journal Science, researchers recently estimated that there are about 3 billion fewer birds in North America than there were in 1970. That’s a reduction of 29% in five decades. As Ken Rosenberg, one of the study’s authors and a senior scientist at the Cornell Lab of Ornithology and American Bird Conservancy, explained in an interview, the researchers drew on two detailed but unrelated sets of data. One is weather radar data, which allows the scientists to observe bird migration patterns over time. The other is a decades-long partnership between scientists and bird watchers. The scientists designed surveys and the birders served as their eyes and ears on the ground, tracking 529 species. Both data sets show similar reduction in the birds’ biomass over time.
My father is among the many Americans who take great pleasure in bird watching. If you show him a picture of a bird or play the sound of a bird call, he can tell you what it is. While I didn’t inherit his passion for the hobby, I have always been impressed with his knowledge on the subject. But even for those of us who cannot tell a finch from a chickadee at a glance, 3 billion missing birds is alarming.
Birds serve crucial functions in a variety of ecosystems, as both predators and prey. They also play an important role in moving pollen and seeds throughout an ecological system. Losing them could cause a variety of environmental problems. The study’s authors note that they found it was not only precarious species that were in trouble. Common birds like meadowlarks and red-wing blackbirds also saw sharp population declines. Rosenberg and his co-authors suggest that the loss of birds may indicate other, less closely observed populations of animals are also struggling. Back in February, an analysis published in the journal Biological Conservation sounded an alarm about a sharp drop in more than 40% of insect species worldwide. (This despite the missing birds, many of which are major insect predators.)
To help birds recover, we need to pinpoint the causes of their decline. The recent study does not cover these causes directly; this is the team’s next area of study. Unfortunately, it seems likely that there are several factors working in concert. According to Rosenberg, the most critical factor is almost certain to be habitat loss. America’s prairies have steadily become farmland, and grassland birds have suffered more than those native to other habitats. While changes to the climate are not the sole driver of declining bird populations, they can also contribute to the loss of suitable habitats. Potential secondary factors contributing to fewer birds include urbanization and the attendant spread of artificial light, which result in fatal collisions with windows and tall buildings; widespread pesticide use; and predation by domestic pets, especially outdoor cats, which kill an estimated 2.4 billion birds each year.
The organizations behind the recent study suggest that individuals can take actions to help protect North America’s birds. These seven suggestions include keeping cats indoors and making windows more visible to prevent collisions. But individuals, however well-intentioned, cannot turn the tide alone.
Some of the actions the authors suggest will be much more useful if implemented at scale. Limiting or eliminating pesticide use, for example, will have greater effect when adopted by industrial farms than by individual homeowners. Plastic reduction, too, is a matter more effectively handled at levels higher up than the individual consumer. And it is up to governments, not individual citizens, to set limits on development and urbanization.
Conservation concerns are a hot political topic right now, especially to the extent they have some tie to climate change. In the United States, room for action and compromise is hard to find. The current president has outright dismissed the projected economic effects of climate change, and much of his party (though not the majority) agrees. As part of its push towards deregulation, the Trump administration reduced the scope of the Migratory Bird Treaty Act last year – a move in the wrong direction considering the threats American bird species face. Meanwhile, many of the loudest voices among the Democrats are pushing for major changes that would require huge resources to put into place. Both parties seem more inclined to sweeping proclamations than to smaller, concrete actions.
As long as both sides insist on grand gestures, political gridlock keeps us from doing much of anything. Our political process is, by design, often slow. But as the birds are showing us, conservation problems will not always wait for the gears of government to grind through. A timely solution will involve compromise and cooperation. Such efforts can be made, though we see them too rarely.
Rosenberg told The Wall Street Journal: “Birds are literally the canary in the coal mine.” We need to find a way to take action before we lose species and populations for good.