Next Sunday, April 22, is Earth Day. I hope you will take the time to think about how you can make a difference in the protection and conservation of our planet’s organisms and resources. This year a major push on Earth Day is to try to eliminate plastic pollution.

Many birds die because of direct human activities (for example, overhunting) or indirect effects of our use of the earth (for example, habitat destruction and pollution (including plastics). Today we will consider birds that have been pushed over the brink to extinction because of human activities. This sobering topic should make us all take Earth Day even more seriously. Extinction is forever.

Over the past 500 years, over 140 species of birds have gone extinct. With the exception of only about a dozen species, these birds were driven to extinction by human activities. Of the roughly 11,000 existing bird species, 1,200 are in danger of extinction.

The majority of these extinctions occurred on oceanic islands. Many of these islands are small so bird population sizes are never very high. Some birds on oceanic islands become flightless over time and are therefore unable to escape from human hunters or the pets humans bring to islands. Birds on oceanic islands with few predators are often fearless in the presence of humans or introduced predators.

But bird extinctions don’t happen only on islands. We have lost at least three species of North American birds in the past 200 years. We can clearly point an accusing finger at ourselves for two of these extinctions.

The passenger pigeon was once the most abundant bird in North America, migrating in astoundingly large flocks. They were colonial breeders, nesting sometimes in groups of 100,000 birds or more. The pigeons were hunted commercially as a cheap food for slaves and the poor. The pigeon population declined slowly from 1800 until 1870. As a result of more sophisticated capture techniques, the passenger pigeon population plummeted over the next 20 years with the last major harvest taken in 1896. These pigeons, once numbering in the billions, were hunted to extinction.

The Carolina parakeet, the only parrot in eastern North America, went extinct in part because of deforestation and the killing of birds for use in ladies’ hats and for protection of fruit crops. Their range extended from Nebraska east to Ohio as the northern limit, extending as far south as Texas and Louisiana. Northern populations migrated to the southern U.S. in winter.

The last Carolina parakeet died in captivity in the Cincinnati Zoo in 1918, just four years after the last passenger pigeon died at the same institution.

We know little about the extinction of the Labrador duck. In all likelihood the Eskimo curlew and Bachman’s warbler are extinct as well, with humans having a significant role in their decline.

Thankfully, birds are given much stricter protection now. The year 2018 is happily the centennial of the Migratory Bird Treaty Act, an agreement between the United States and Great Britain (acting on behalf of Canada) to grant federal protection to over 800 species of birds.

People may not kill, capture, relocate or sell any of the birds on the list. Nests, eggs and even feathers are protected as well. The treaty does not distinguish between living and dead birds. Possession of a feather is against the law.

You may wonder why the treaty is so draconian. What’s the harm in picking up a blue jay feather to put in your pencil jar on your desk? The strict law prevents people from killing birds and then claiming they were found dead. This treaty has teeth!

Federal permits may be granted for taxidermy, scientific purposes, religious uses of Native American tribes or relocating problem birds but such permits aren’t easy to obtain.

Herb Wilson teaches ornithology and other biology courses at Colby College. He welcomes reader comments and questions at

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