It's time to start paying close attention to birds. That's what a group of scientists and students from Stanford University in California says.

A review of data on all of the world's known bird species (nearly 10,000!) has led to a worrisome conclusion. Between 500 and 1,300 bird species will vanish by the year 2100, the researchers predict. As many as 1,050 more will dwindle to such small populations that they'll basically lose their place in the web of life.

The birds that are most at risk include scavengers, fish eaters, fruit eaters, and nectar sippers. The scientists based their predictions on information about habitat, diet, and range, among other factors.

In the past 500 years, by comparison, only 129 bird species are known to have disappeared.

As the birds go, other parts of ecosystems might start falling apart, too. Some bird species, for instance, pollinate only certain types of plants. And these plants might not survive without them.

Vultures in Asia provide another example of what can happen when food webs lose their shape. In the past decade, lots of vultures have died after eating carcasses of livestock that had been given medicine. Such drugs keep the animals healthy, but they're poisonous to the birds (see A Vulture's Hidden Enemy).

As vulture numbers have declined, populations of their competitors have grown in size. This group includes wild dogs that spread disease.

Without help for the birds, then, the world might end up looking like a very different place. And we might suffer, too.—E. Sohn