Three Billion Birds Gone. According to the American Bird Conservatory, “ In less than a single human lifetime, 2.9 billion breeding adult birds have been lost from the United States and Canada, across every ecosystem and including many familiar birds.”
The Dark-eyed Junco has lost an incredible 175 million individuals from its population. The White-throated Sparrow has lost 93 million. Of the nearly 3 billion birds lost, 90% came from just 12 bird families, including sparrows, warblers, finches, and swallows. The article describes it as a “biodiversity crisis”.
These findings were reported in the world's leading scientific journal, Science, by researchers at seven institutions. Read the full story at https://abcbirds.org/3-billion-birds/.
Although the study did not investigate causes, scientists have identified habitat loss as the biggest overall driver of bird declines. Habitat loss occurs when land is converted for agriculture, development, resource extraction, and other uses. Habitat degradation was a second cause of losses. In this case, habitat doesn't disappear outright but becomes less able to support birds. The principle causes appear to be farming and development, pesticides and climate change.