Huge bird loss causes fears for ecosystems
LOS ANGELES: North America has lost nearly three billion birds since 1970, according to a new analysis of bird survey and radar data.
The sharp decline, described in a study in the journal Science, is not just bad for birds. It also bodes ill for the ecosystems those birds inhabit, and points to a need for action to halt and perhaps reverse the drop, scientists said.
‘‘Three billion was a pretty astounding number for us,’’ said lead author Kenneth Rosenberg, a conservation scientist at Cornell University and American Bird Conservancy.
Steven Beissinger, a conservation biologist at the University of California, Berkeley, called the results and their implications ‘‘dizzying’’.
Of those lost birds, 90% come from just 12 bird families, including common and widespread species such as sparrows, swallows, warblers and finches.
Declines in the abundance of common species might not seem as dramatic as the endangerment of rare ones but it was a very serious form of ecosystem erosion, the scientists said.
That was because abundant species often played important roles in their habitats, whether they controlled pests, pollinated flowers, dispersed seeds, provided food for other animals or even drew tourists who supported local economies.
Across ecosystems, grassland birds — a group that includes sparrows and meadowlarks — were hit the hardest, losing 53% of their initial population, the researchers said. And shorebirds declined more than 37%. — DPA