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By the Numbers: The Billions of Animals Killed by Cats

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By Chris Gayomali/The Week

The internet loves cats. And why not? They're cute, endlessly entertaining and, unlike dogs, don't require constant attention. But what do cats do when they're not curling up in your lap? According to biologists, they're off killing other animals — billions of 'em. Scientists from the Smithsonian Conservation Biology Institute and the Fish and Wildlife Service estimate that each year, apparently bloodthirsty felines are preying on billions of birds and small mammals like indigenous chipmunks, shrews, and meadow voles. "When we ran the model, we didn't know what to expect," researcher Dr. Peter Marra told the New York Times. "We were absolutely stunned by the results." The model, which crunches numbers from 21 existing studies, is the first of its kind in the United States, and follows on the heels of a controversial plan in New Zealand to eliminate the nation's cats. Here's a look at our killer cats, by the numbers:

84 million

House cats in the United States

4 to 18

Birds killed by a typical house cat every year

8 to 21

Small mammals killed by a typical house cat every year

30 million to 80 million

Free-roaming, feral cats estimated to be living in the United States. They either survive alone or live in colonies. In Washington, D.C., for example, there are estimated to be some 300 outdoor cat colonies.

23 to 46

Birds killed by each feral cat every year

129 to 338

Small mammals killed by each feral cat every year

1.4 billion to 3.7 billion

Total birds killed by America's cats every year

15

Percentage of all bird deaths estimated to come at the hands — er, paws — of cats

6.9 billion to 20.7 billion

Total small mammals killed by cats every year

2 to 4

Factor by which these newly estimated kill rates are higher than mortality figures previously suggested. "Our findings suggest that free-ranging cats cause substantially greater wildlife mortality than previously thought and are likely the single greatest source of anthropogenic mortality for U.S. birds and mammals," the study's authors conclude. "Scientifically sound conservation and policy intervention is needed to reduce this impact."

Sources: LiveScience, New York TimesUSA Today

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environment
The Roomba's Creator Invented an Underwater Vacuum That Sucks Up Invasive Lionfish
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Invasive fish can be a major issue for waterways, since they can devastate native species and take a toll on environmental diversity. The red shiner, for instance, is a hardy fish that can survive basically anywhere, and in the process, outcompete and kill native fish species. Invasive species can travel far and wide, hopping across continents with human help (whether on purpose or by accident).

Colin Angle, who co-founded iRobot, the company that invented the Roomba, has an answer. It’s kind of like a robot vacuum, but for invasive fish, according to Fast Company. The Guardian, developed by Angle’s nonprofit Robots in Service of the Environment, is an underwater robot designed to stun lionfish, suck them up, and bring them to the surface.

Lionfish, native to the Indo-Pacific, are considered an invasive species in the Atlantic and the Caribbean, where they have few predators and huge appetites for both crustaceans and other fish. The fish can eat up to 20 other fish in half an hour, lay up to 40,000 eggs every few days, and live up to 30 years, making them a formidable foe for environmentalists. They may have been introduced in the mid-1980s by personal aquarium owners in Florida releasing pets that got too big for their tanks.

As part of the effort to rid Atlantic waterways of lionfish, the U.S. government has tried to encourage people to catch and eat them. If other species can be overfished, couldn’t lionfish?

The Guardian isn’t the only robot with a mission to eradicate invasive fish. Queensland University of Technology’s COTSbot is designed to kill crown of thorns starfish in the Great Barrier Reef. Unlike COTSbot, though, The Guardian isn’t autonomous. Someone above the water has to control it remotely, directing it toward fish to suck up using a camera feed.

That’s by design, though. The idea is that like the Roomba, the Guardian will be affordable enough for fishermen to use so they can hunt the fish and sell them in restaurants. (One unit currently costs about $1000.) The Guardian's ability to reach depths of up to 400 feet will aid fishermen in waters and reefs that can't be easily accessed.

Each Guardian can bring up about 10 live lionfish at a time. And while one robot cannot eradicate lionfish from the ocean alone, a huge number of them could make a dent.

The Guardian is currently in testing in Bermuda.

[h/t Fast Company]

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Climate Change Could Resurrect the Dust Bowl
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The billowing dust storms we know from black-and-white photos of the Great Depression could become a reality for future generations, scientists warn. As Gizmodo reports, climate change is grooming the southwest and central Great Plains for a new version of the Dust Bowl that plagued the region in the 1930s.

After gathering 12 years of satellite data (2003–2015), researchers at Princeton University and NOAA's Geophysical Fluid Dynamics Laboratory predict that dust clouds will increase in parts of the U.S. in the latter half of this century. As they lay out in their study in Scientific Reports, prolonged drought and barren landscapes caused by deforestation are set to create the perfect conditions for the same type of storms that drove people from the Great Plains nine decades ago. At its worst, this phenomenon could be deadly; when they're not breathing in dust, residents in the affected areas could be exposed to dangerous pathogens and chemicals carried by air currents.

Dust storms occur when winds stir up dirt particles into dark, massive clouds. During the so-called Dirty Thirties, soil loosened by over-tilling was a major contributor to the dust that enveloped land. Even with more sustainable farming practices, dry summers could create the same arid, dusty landscapes required for a repeat of the Dust Bowl.

While there's still much research to be done on the subject, the study authors hope their findings will get people thinking about how to prepare for the consequences. "Our specific projections may provide an early warning on erosion control, and help improve risk management and resource planning," co-author Bing Pu said in a Princeton University press statement.

That seems like an improvement over ideas for fighting the Dust Bowl that were proposed in the 1930s, which included paving over the Great Plains and bombing the sky. Fortunately, we still have a few decades to come up with better strategies this time around.

[h/t Gizmodo]

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