Diario del proyecto Denton Wild

New York Times

URL: https://www.nytimes.com/2019/09/19/science/bird-populations-america-canada.html?utm_source=pocket-newtab
Accessed: 22 September 2019

Birds Are Vanishing From North America

The number of birds in the United States and Canada has declined by 3 billion, or 29 percent, over the past half-century, scientists find.

By Carl Zimmer
Published Sept. 19, 2019; Updated Sept. 21, 2019

The skies are emptying out.

The number of birds in the United States and Canada has fallen by 29 percent since 1970, scientists reported on Thursday. There are 2.9 billion fewer birds taking wing now than there were 50 years ago.

The analysis, published in the journal Science, is the most exhaustive and ambitious attempt yet to learn what is happening to avian populations. The results have shocked researchers and conservation organizations.

In a statement on Thursday, David Yarnold, president and chief executive of the National Audubon Society, called the findings “a full-blown crisis.”

Experts have long known that some bird species have become vulnerable to extinction. But the new study, based on a broad survey of more than 500 species, reveals steep losses even among such traditionally abundant birds as robins and sparrows.

There are likely many causes, the most important of which include habitat loss and wider use of pesticides. “Silent Spring,” Rachel Carson’s prophetic book in 1962 about the harms caused by pesticides, takes its title from the unnatural quiet settling on a world that has lost its birds:

The Atlantic |

URL: https://getpocket.com/explore/item/spiders-can-fly-hundreds-of-miles-using-electricity?utm_source=pocket-newtab
Accessed: 28 September 2019

SPIDERS CAN FLY HUNDREDS OF MILES USING ELECTRICITY
Scientists are finally starting to understand the centuries-old mystery of “ballooning.”

By Ed Yong

On October 31, 1832, a young naturalist named Charles Darwin walked onto the deck of the HMS Beagle and realized that the ship had been boarded by thousands of intruders. Tiny red spiders, each a millimeter wide, were everywhere. The ship was 60 miles offshore, so the creatures must have floated over from the Argentinian mainland. “All the ropes were coated and fringed with gossamer web,” Darwin wrote.

Spiders have no wings, but they can take to the air nonetheless. They’ll climb to an exposed point, raise their abdomens to the sky, extrude strands of silk, and float away. This behavior is called ballooning. It might carry spiders away from predators and competitors, or toward new lands with abundant resources. But whatever the reason for it, it’s clearly an effective means of travel. Spiders have been found two-and-a-half miles up in the air, and 1,000 miles out to sea.

This article was originally published on July 5, 2018, by The Atlantic.