3 Billion Birds are Missing — thoughts on the study

by Sep 30, 2019

There was a paper published in Science magazine recently based on research done by Ken Rosenberg and a team at the Cornell Lab of Ornithology and other organizations that seems to have some very dire warnings: By comparing data from the 1970s to current data, they’ve concluded we’ve seen a huge decrease in the number of birds living in North America in the last 50 years, by over 3 billion individuals, or a loss of 29% of the continent’s bird population. This is a great example of the kind of science we can accomplish because birders have been involved in citizen science for decades through activities like our annual Christmas Bird Counts (please get involved this year if you’ve never done one! Expect info on how to get on a count team for this winter’s counts coming in a few weeks), weather radar tracking of migrations, and via our use of eBird as a reporting and tracking tool in the last few years.

A well-written write up about this study was published in Smithsonian and I recommend it to you if you haven’t seen it as a good and thoughtful take on the research.

But the raw numbers and screaming headlines might not completely represent what the data is actually telling us, and that worries me. People are starting to look into the numbers and there are some nuances that I worry might give those that want to discount the problem (and climate deniers in general) reasons to refute and ignore the data.

One researcher who took a look, Brian McGill of UofMaine, published Did North America really lose 3 billion birds? What does it mean? and while he finds the numbers and science credible, he has some questions about the assumptions and how things are being interpreted. This one gets a bit nerdy but it’s fascinating reading.

Another piece that uses McGill as a reference is by Michael Schulson, and he published A Second Look at the Bird Population Decline Study on the site Undark, which was then republished by the Bay Nature people. His take: A recent paper in the journal Science documented declines in some bird populations, but did the packaging and coverage paint a skewed picture?.

There is some interesting nuance to that large, scary number in his look at the data:

Basically, if you lump the species into two groups: the 40 species with the biggest losses, and everyone else, the latter group most or less looks okay. Some species have lost numbers, some have gained, species have moved around, etc. But for all but those 40 species, there doesn’t seem to be a big problem.

Within those 40 species, two: European Starling and House Sparrow, account for almost 15% of the loss — and those are two introduced, invasive species where there are areas with active eradication programs in place. That brings up a question of whether that loss is a bad thing at all, something the original study ignored, and whether those numbers should have been included in the big scary number in the headlines (my take: no, they should have been excluded).

There are also some questions about whether the numbers from the 1970s were inflated, and how real the actual losses are because of that.

Having said all that: the study does show that there are a number of species having big problems that deserve (at the least) more study and probably protection.

The ten species with the biggest number declines are: House Sparrow, Blackpoll Warbler, Horned Lark, Dark-eyed Junco, Savannah Sparrow, Pine Sisken, White-Throated Sparrow, Red-Winged Blackbird, European Starling and Common Grackle. Either of those species are considered “Least Concern” on the UICN list and the other two (Common Grackle and Blackpoll Warbler) are listed as “Not Threatened” — so the vast majority of the losses in that 3 billion number — over 50% — are from those 10 species where we still have huge, healthy populations that don’t need special attention.

I agree with Brian’s take on this:

So do the statistics in this study really directly address questions of conservation or biodiversity preservation? Not so much (at least not in the headlines). For that you need to go look at birds that are rare and declining. Of course that is what conservationists have been doing all along. And there you get a mixed story. Bald Eagles and Wild Turkeys have made pretty spectacular come backs. And the Kirtland Warbler and California Condor are both naturally rare but have actually increased in recent years due to intensive management efforts so fairly positive results but certainly not victory. But we have made several bird species go extinct including the Carolina Parakeet, Heath Hen, Passenger Pigeon, Labrador Duck and probably the Ivory Billed Woodpecker and a few more (many more if we include Hawaii). And a number of other species are on the ropes (a few dozen endangered bird species in North America, again a disproportionate fraction of them in Hawaii). That is a really important story (both the positive and the negative), but it is an almost wholly different story than -3,000,000,000 or -29%.

My worry is that the headlines are screaming Apocalypse, yet when you look into the numbers the results seem different, and may push interest away from the species that are declining and in need of help, like the Red Knot, which in this study seems to get lost in the noise.

I wanted to post this as an Advocacy piece because of all of the media attention, to give you access to the information and the data, and also to some of the nuance within the data and behind the headline, because I know I’m getting asked about this by my non-birder friends and I expect most of us are. This will help you better understand how to answer them when they ask what’s going on, and perhaps help us all better understand not just the headlines, but what the data in the study actually say.

Cornell and the researchers clearly knew they had a chance to get some big media play on this study and they did. My worry is that the way it’s been promoted to the media with that huge scary number may well backfire because when you look at the details of that number, you see a much different story than the mass media has been running with, and that opens this study and it’s implications to some backlash as opponents realize that.