Numbers great enough to block out the sun
- John Lorson: The Rail Trail Naturalist
- December 6, 2024
- 402
As I made my way home the other day, a low, black cloud boiled just above the treetops a mile or so away.
As I approached closer, it rose like a living mirage into an hourglass-shaped pillar hundreds of feet in the air, only to suddenly turn, drop and thicken into a dark, black mass headed right in my direction. I barely had a moment to grab my camera as thousands of jet-black birds passed directly overhead. The flock, consisting mostly of common grackles, swirled away in a noisy cacophony, leaving me with a handful of photographs and the perfect inspiration for this column.
Imagine for a moment the flocks of blackbirds we encounter at this time of year (typically a mix of grackles, red-winged blackbirds, starlings and cowbirds) were so large they blotted out the sun for hours or even days on end as they passed. That a single indiscriminate shotgun blast toward the sky could bring dozens of birds to the bag. That the mass of life was so thick and focused that one could simply stand with a tall pole on a hilltop where the flocks skimmed nearest the Earth and knock hundreds of individuals to the ground in a morning’s hunt. That a coordinated group of men could fill a railroad car with the kill of just a single day. Such was reality as the passenger pigeon filled the skies from the time of European settlement of North America all the way into the mid to late 1800s.
Similar in shape but larger and more vibrant in coloration than the mourning dove, the swift and social passenger pigeon flocked, roosted and nested in almost unimaginably large numbers.
The largest accurately recorded nesting, which covered 850 square miles of forest in Central Wisconsin in 1871 — that’s twice the size of Holmes County — was calculated to contain hundreds of millions of birds. In hardwood forests where the flocks would land to feed on acorns, beechnuts, hickory nuts and chestnuts, birds would accumulate so thickly among the branches that 2-foot diameter limbs would break and fall to the forest floor, killing thousands of birds perched below.
As a keystone species, the passenger pigeon has been credited not only with spreading the very seeds of the hardwood forests that predominated after the last period of glaciation, but also with providing vast areas of super-fertilized lands where other species could take root.
The bird’s habit of flocking in vast numbers is a model of the concept of “predator satiation” — a concept whereby any predator encountering the flock could literally eat its fill and never even put a dent in the overall population. This method of survival worked wonderfully until men with guns, nets, and the advanced technologies of telegraph communication and railroad transportation turned pigeon flesh into a marketable commodity.
We can talk about the 3-5 billion birds that existed into the mid-19th century, but the real story comes down to a period of only 30 years when the flocks were so viciously persecuted that the population spiraled from hundreds of millions to a single remaining bird that died in the Cincinnati Zoo on Sept. 1, 1914, a casualty of the unchecked appetite of man.
Learn more about the passenger pigeon’s outsized life and incomprehensible death in the outstanding book, “A Feathered River Across the Sky” (Joel Greenberg, 2014).
If you have comments on this column or questions about the natural world, write The Rail Trail Naturalist, P.O. Box 170, Fredericksburg, OH 44627, or email jlorson@alonovus.com. You also can follow along on Instagram @railtrailnaturalist.