The Canary in the Coal Mine: Why did passenger pigeons go extinct?


Why did passenger pigeons go extinct?


Why did passenger pigeons go extinct?

Passenger pigeons used to be incredibly abundant in North America. There were literally billions of them. When they took flight together, they would often obscure the sun. But their extinction at the end of the 19th century and into the early part of the 20th century happened so fast, that people barely noticed until it was too late.

Passenger pigeon illustration
Passenger Pigeon, Mark Catesby, 1731. Image via Wikimedia Commons. Public Domain.

So, why did they go extinct? Well, this is actually a bit of a controversial subject, believe it or not. There are a few theories. The first theory has to do with their diet, which mostly consisted of mast. These include things like acorns and beechnuts. When many trees in their habitats were cut down, there simply wasn’t enough food to go around. Many believe this caused their demise.

Another theory is that humans killed numerous pigeons for sport and for food. Tourtière, for example, is a Quebecois and Acadien holiday classic. But it wasn’t always made with pork. Passenger pigeons used to be a staple in this flakey, buttery pastry. And they were so overhunted by settlers, that they were literally eaten to death.

But there’s another layer to this story. Eric Guiry, a Post-Doctoral Fellow at Trent University, shared how combining research in archaeology and science helped uncover important information about passenger pigeons. In this informative The Conversation article, he explains how his research team found a possible third driver for their extinction after analyzing the chemical markers of their bones along with their DNA. In a nutshell, they found that many passenger pigeons were not exclusively eating mast. Many were actually eating farmers’ crops, which they believe is evidence of an unchecked commercial pigeon industry. When the researchers compared samples of earlier pigeons to ones that died shortly before the extinction, their data suggests that genetic diversity was waning. And for species to thrive and to be able to fight off things like diseases, they need genetic diversity.

So long story short, as for many species that have gone extinct or are at risk, hunting, habitat destruction, and/or a lack of genetic diversity were likely the cause of their demise.

White and brown bird perched on person's hand in woods
Photo by Alex Iby on Unsplash

Birds and Environmental Health

Fast forward to present day and scientists have estimated that nearly 3 billion birds of various species have already disappeared from Canada and the US since the 1970s. As outlined in a study published in Science Magazine, they frame their findings in a different way. Rather than focusing on extinction, the study is centred on “loss of abundance within still-common species.” Birds are essentially the canary in the coal mine when it comes to environmental health and ecosystem integrity, according to the Globe and Mail. They are dying off largely due to habitat destruction and pesticide overuse. The Global Assessment Report on Biodiversity and Ecosystem Services revealed that 75% of land-based environments and 66% of marine environments have been “significantly altered by human actions”.

How can you help birds?

We have all the science, information and technology we need to act now on not only protecting birds but also tackling biodiversity loss. Focusing our efforts on protecting habitats is a great first step. We can do this by improving farming, forestry and industry practices. We can work on banning pesticides, especially in areas where birds nest. We can also reduce and tackle plastic pollution, especially since some species of birds inadvertently use plastic debris for nest building.

The Cornell Lab of Ornithology shared a series of simple actions that you can take at home. These include making your windows safer, keeping cats indoors, planting native species, and drinking shade-grown coffee. Also, now is a great time to become a birder-watcher or citizen scientist.

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