Three Billion Birds Are Missing. What Happened?

Picture of a blue Steller's jay with a black head sitting on a mossy branch for article about how birds are missingAs fall migration begins, I’ve been watching the feeders outside my studio window to see how the cast of characters changes as the days pass. Today’s been relatively quiet, other than a juvenile American goldfinch (Spinus tristis) loudly hassling its father for food (in spite of the food being right there in front of it!)The black-headed grosbeaks (Pheucticus melanocephalus) haven’t been around for weeks, though they were never frequent visitors. The purple finches (Haemorhous purpureus) are beginning to thin out as well. The Steller’s jays (Cyanocitta stelleri), on the other hand, still happily show up for peanuts, and will imitate the local red-tailed hawks (Buteo jamaicensis) if they want to scare everyone off and have the feeder to themselves. But it gets me thinking about how more than just the migrating birds are missing.

It Took Less Than a Lifetime

I was born in the late 1970s, and from a very young age I loved being outside. I was fortunate enough to live in suburbs and small towns where there was enough open land to support human-tolerant wildlife populations, and I spent countless hours exploring nearby woods and fields, as well as my own yard.

Birds, of course, were among the easiest animals to observe, and certainly the most visible vertebrates. My Midwestern home was full of American robins (Turdus migratorius), blue jays (Cyanocitta cristata), mourning doves (Zenaida macroura), and numerous other species. They sang in the trees and on power lines, searched for food in the yard, flew overhead, and occasionally–sadly–ended up deceased due to cars, cats, or unknown natural causes.

I haven’t lived there for many years, having since sojourned in other places and ending up living in several locations in the Pacific Northwest.  So I don’t have a good firsthand comparison of population numbers from childhood versus today, at least not involving a single site. Thankfully there have been more methodical and thorough assessments of the changes in population numbers, but unfortunately the news isn’t good.

Three Billion Birds Are Missing

A 2019 study showed that the cumulative number of breeding individual birds in North America has dropped by 2.9 billion in the past fifty years, just a little longer than my own lifetime. If we assume that the sex ratio is roughly 50-50, and we optimistically assume that the bulk of these birds would have been able to find mates if they existed, then we’re probably looking at over a billion fewer nests of eggs being incubated each year. Even if we look at the standard estimate that 2/3 of nestlings won’t survive to breeding age, that’s still over 300 million babies that would have made it into the breeding populations of their species–if they existed, that is.

Black and white photo showing a passenger pigeon and a mourning dove in the same tree for article on why birds are missingNow, obviously, we didn’t lose all of them at once. Rather, this is a comparison of the total number of wild native birds of all species found in North America fifty years ago, versus the total number now. Even with normal population fluctuations due to environmental pressures, expected mortality levels, and so forth, the fact that we are seeing millions fewer birds is concerning. And it’s not just affecting rare species, but even the most common ones we’re used to seeing in large numbers.

(Incidentally, September 1 marked the 108th anniversary of the death of Martha, the very last passenger pigeon (Ectopistes migratorius), a species that dropped from an estimated population of 3-5 billion to zero in less than half a century. Sound familiar?)

What Happened To Them, and What Can We Do About It?

There are several factors that are contributing to the rapid decline in bird populations overall:

Image of a great blue heron standing on the edge of a river for article on why birds are missingIf I’m lucky, I’m only halfway through my lifetime. I would love to see this downward trend reversed. Even if my twilight years won’t show me the same numbers of birds as my childhood, I’ll count myself fortunate if on my last day I’ll no longer have to say that quite so many birds are missing from our bright, beautiful, biodiverse world.

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