During much of the 20th century, miners carried caged canaries into coal mines to serve as an early warning system for the presence of toxic gas, such as colorless and odorless carbon monoxide. Birds need immense amounts of oxygen to enable them to fly, so their anatomy has evolved to give them a double dose, once when they inhale and once when they exhale. If it's not oxygen but CO2 in the air, these "sentinel animals" feel the effects far faster than humans, giving the miners time to evacuate.
Honeybees, whose populations have declined significantly in recent years, are considered a sentinel animal for pesticide use because they depend on agricultural crops for sustenance. Insects in general are sentinel animals for habitat loss, pollution, and invasive species. A synthesis by Australian scientists of 73 studies conclude s that 40 percent of insect species are threatened with extinction, and each year another percent is added to the total.
Climate change is also considered a factor in the loss of honeybees and other insects, although the relative impact versus other factors is difficult to quantify. Now, new research released by the National Audubon Society concludes that 389 bird species in North America, two-thirds of all our birds, are at increasing risk of extinction. And the scientists point the finger squarely at warming temperatures and other knock-on effects of climate change.
As birds change their ranges because of a changing climate, at least eight states will see their official "state birds" largely or entirely disappear. These include the brown thrasher in Georgia, the purple finch in New Hampshire, the goldfinch in Iowa and New Jersey, and the loon in Minnesota.And rising sea levels will do significant damage to birds who build their nests in sandy areas along the coast, such as the piping plover.
Benjamin Zuckerberg, an ecology professor at the University of Wisconsin warns, "there is a real concern that the rate of climate change is going to be beyond the ability of many species to adapt."
So does it matter? Well, not if you don't mind a new, updated edition of Rachel Carson's "Silent Spring." Or, as hotter temperatures creep northward, waking up to the shrill squawks of parrots and mynah birds.