North American shorebird populations have declined by more than a third since 1970. Photo: Jacqueline Larma, AP

According to a study in the Journal Science published last Friday, bird populations have declined nearly 30 percent — a loss of 3 billions birds — in the last fifty years.  The study did not look at the reasons but one of the co-authors called it a “wake up call.”  In another paper published in the Journal of Ecology Letters, the authors looked at the resilience of bird populations and found that they are relatively resilient to natural events like hurricanes, but through destruction of bird habitat, introduction of alien predator species, and other environmental harms like pesticides, humans are the ones putting birds (and other species too) at risk.

Why This Matters:  There is some good news — because of specific efforts to conserve them, some types of birds are actually doing better — like raptors and ducks — but others are having a harder time. National Public Radio interviewed Elise Zipkin, a quantitative ecologist who explained that the sheer numbers are remarkable and the loss of individuals can be a big problem.”Just because a species hasn’t gone extinct or isn’t even necessarily close to extinction, it might still be in trouble,” she says. “We need to be thinking about conservation efforts for that.”  We need to figure out how the various human impacts like habitat loss and pesticides are impacting particular birds and try and address those if we want to turn things around.  Interestingly, some of the data used to quantify bird loss came from weather stations — proving that more weather data is better for lots of reasons!

Which Populations Are Losing

The authors found that “more than 90% of the loss can be attributed to just a dozen bird families, including sparrows, warblers, blackbirds, and finches.”

• According to NPR, the common bird species experiencing “decreasing populations include meadowlarks, dark-eyed juncos, horned larks and red-winged blackbirds.”
• Specifically, “Grassland birds have suffered a 53% decrease in their numbers, and more than a third of the shorebird population has been lost.”

How did they determine the extent of the loss?  The Guardian reported that researchers used 10 years of information on migratory birds from weather radar stations and 50 years of data from the ground.

What Is Humans’ Role?

According to the Ecology Letters study, many birds are resilient and thus when severe events like hurricanes cause a species to go extinct, it is because the species is already weak due to humans impacts.

• The Times reported that according to David Steadman, a bird researcher with the Florida Museum of Science, “If what we’re worried about is extinction, ‘we’re the driving force.'”