Not Yet a ‘Silent Spring,’ But a Subdued One

Human Numbers Up, Bird Numbers Down: Not Just a Coincidence

Fewer flocks and feathers grace our skies, forests, coasts, grasslands, and deserts these days.

A team of scientists writing in the journal Science reports that the number of birds in North America has dwindled by about 30 percent since 1970, or nearly three billion individual birds. The number of breeding birds in the United States and Canada was estimated at 10 billion in 1970. Today that number has plummeted to approximately 7.1 billion.
At the same time, the number of people living in the USA and Canada combined grew by 140 million or 63 percent, soaring from about 225 million (USA 205 million; Canada 20 million) to 366 million today (USA 329 million; Canada 37 million).
The populations of people and birds are inversely related, as seen in this graph from The Overpopulation Project. This means that when one goes up, the other goes down.

Change in bird numbers and human numbers in North America, 1970-2018. Sources: Rosenberg et al., “Decline of North American Avifauna” Science 2019; United Nations Population Division, World Population Prospects 2019.
Why should this be the case? Because humans and birds (and indeed all vertebrates) compete for many of the same limited resources: habitat, land, food, energy, and water. Loss of natural habitats – to agriculture (cropland and pasture), urban sprawl and development (asphalt, concrete, and buildings), energy, water, and transportation projects – is the single greatest threat to the survival and abundance of our avian neighbors.

Black-throated Blue Warbler with Nestlings. Warblers are among the hardest hit birds, with an estimated 617 million fewer birds than in 1970.
Golden eagle populations, for example, are expected to decline throughout this century as a result of increasing collision with proliferating man-made objects such as wind turbines, power lines, and communications towers in their once nearly-empty Western habitat.
In just the 16 years between 2001 and 2017, more than 24 million acres of natural lands and habitats were permanently altered or lost to development according to a 2019 study by scientists at Conservation Science Partners, equivalent to ten Yellowstone National Parks in area.
Other known threats to birds that are likely implicated in this sharp decline include the continuing use of vast volumes of pesticides (insecticides, herbicides, fungicides, etc.) more than half a century after Rachel Carson wrote Silent Spring. The class of insecticides known as neonicotinoids is raising concerns for birds as well as bees.
There is also growing evidence that insects themselves – including bees, beetles, butterflies, moths, dragonflies, and damselflies – may be in decline around the world. One recent German study reported a decrease of 82 percent in the summertime biomass (total weight) of flying insects in the last 25 years even in protected areas in Germany. Another study referred to this staggering loss as an “Ecological Armageddon.”

The majestic golden eagle is legally protected by the Bald and Golden Eagle Protection Act, but this doesn’t protect it from colliding with man-made objects proliferating in a once nearly empty, but now increasingly cluttered, Western landscape.
On the opposite side of the Atlantic, and in the tropics, a 2018 study reported in the Proceedings of the National Academy of Sciences found decreases in the biomass of arthropods (invertebrates with exterior skeletons), lizards, frogs, and insect-eating birds in the El Yunque National Forest of Puerto Rico between 1976 and 2012.
Many species of birds of course, feed on insects (thereby helping control their numbers) and depend upon them for their survival. More and more communications towers, power lines, wind turbines, and domestic cats all take their toll on bird numbers.
Colorado State University Professor Phil Cafaro, blogging at The Overpopulation Project, writes that:

While the mechanisms leading to bird losses have been varied, and in some cases complicated, the overall picture is about as subtle as a bulldozer flattening a meadow. Over the past half century, human beings have displaced birds and other wildlife. More people and ever larger human economic support systems have meant fewer birds.
Cafaro adds that he looked in vain for evidence of the slightest recognition that the rising human population in North America was a cause of the declining bird population in the original Science paper, major news outlets, and among conservation and environmental groups.
Rather than acknowledging that we need to stop human population growth first and foremost, conservation groups such as 3billionbirds.org and the American Bird Conservancy proffer more politically correct, tame-and-lame solutions as keeping cats indoors, using fewer plastics, and making windows more bird-friendly.
Environmental groups continually gripe about “climate denialism,” but if they would focus on their own population denialism instead they would do honesty and America a favor.
As Roy Beck and I wrote nearly two decades ago in our 2000 paper in the scholarly Journal of Policy History, “The Environmental Movement’s Retreat from Advocating U.S. Population Stabilization,” the growing importance of mass immigration in driving endless U.S. population growth cowed the mainstream environmental establishment and they backed down from their Earth Day 1970 commitment to halting U.S. population growth.
Environmentalists chose to be politically correct rather than environmentally correct, and now they – and North America’s beautiful, beleaguered birds – are reaping the bitter harvest of that cowardice.
LEON KOLANKIEWICZ is the Scientific Director for NumbersUSA