We hear so often about the massive “sixth extinction” now occurring because of global climate change. Species of all kinds are under stress, and in some cases, tremendous efforts are being extended to save particular endangered species, or even to reintroduce species that are already extinct! Rarely, however, do we consider a broader and perhaps more distressing loss – the catastrophic decline in the populations of individuals that comprise each species. Those numbers matter too.
In May 0f 2019, Adam Smith, a specialist in bird populations at the Canadian Wildlife Service, completed a calculation that tapped into the latest advances in radar imagery, satellite photos, and citizen science to supplement conventional bird counts by species across North America. As reported by Anders and Beverly Gyllenhaal in Nautilus Magazine last month (Article), the conclusions were stunning. (Anders and Beverly Gyllenhaal are co-authors of: From A Wing and a Prayer: The Race to Save Our Vanishing Birds. Simon & Schuster. 2023). Over the past fifty years, the overall population of all birds in North America are estimated to have declined by almost 3 billion – a third of the total population. That decline has been steady and precipitous.
This, of course, should not be a surprise. The groundbreaking book by Rachel Carson, Silent Spring, published 60 years ago, led to the banning of DDT, and helped to ignite the environmental movement. Those successes have brought many bird species, including the American bald eagle, back from near extinction. But the overall patterns of human population growth and development and consequent deployment of land to settlement, transportation, agriculture, and industrial production, have continued. The downward trend in overall bird populations continues and is being exacerbated by the now quite visible impacts of global climate change.
Moreover, this pattern is not unique to birds. While counting of individuals among all the various taxa – mammals, birds, lizards, fish, insects, etc. is hardly feasible, efforts have been made to estimate the total biomass by taxa. These results are very distressing. As I reported in A New Perspective on the Blue Planet, livestock and humans make up 96% of all the mammals on Earth: Livestock accounts for 60%, humans 36% and wild stocks are estimated at only 4%. As for bird life – farmed poultry today is estimated to make up 70% of all bird biomass on the planet.
So if you have noticed that there seem to be fewer birds chirping and flitting about now than when you were a kid, you are right. But you can find all you want in the grocery freezer case.