According to
Birdlife international:
Since the year 1500, we have lost over 150 bird species – an extinction rate far higher than the natural background. Today, one in eight bird species is threatened with global extinction, with 197 species Critically Endangered, and Red List assessments show that things are getting worse. Particularly alarming are sharp declines in many formerly common and widespread species. This is a signal of wider environmental problems, and of the erosion of biodiversity as a whole.
This is significant because that's a lot of birds. It's also important to realize that birds are possibly the greatest survivors we know. They are the most hearty species on the planet.
National Geographic points out:
The ice of Antarctica doesn't faze them. Nor does the heat of the tropics. They thrive in the desert, in swamps, on the open ocean, on sheer rock faces, on treeless tundra, atop airless mountaintops, and burrowed into barren soil.
But birds are in trouble. They evolved from DINOSAURS, people.
Through analysis of the inner workings of birds' cells, scientists have been deciphering increasingly urgent signals from ecosystems around the world.
Like the fabled canaries that miners once thrust into coal mines to check for poisonous gases, birds provide the starkest clues in the animal kingdom about whether humans, too, may be harmed by toxic substances.
Over the years, the correlations between bird populations and human populations around the globe has been increasingly studied. The same chemicals and pollutants seeping into different environments–spelling health issues for bird populations–has also shown a correlation in our human population.
Studies have suggested that those same chemicals also may be altering human hormones. A pregnant mother's load of chemicals passes to her baby while it is still in the womb, with evidence mounting that chemicals can alter development of a baby's brain and its reproductive and immune systems, leading to lower intelligence, behavioral problems, and reduced fertility.
Some studies suggest a link between endocrine disruptors and a greater risk of prostate and breast cancers and other diseases. Some research even suggests chemicals can switch genes on and off, affecting grandchildren and great-grandchildren.
Studying bird populations gives us a unique look into future biosphere issues. Bird populations are historically more stable then most mammal populations and in many places they are at the top of the food chain.
Birds have been known to recover. This means we can too. But we need to heed the warnings.
Read more about this issue:
Here and here.