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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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Live Smarter
All National Parks Are Offering Free Admission on April 21
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Looking for something to do this weekend that's both outdoorsy and free? To kick off National Park Week, you can visit any one of the National Park Service's more than 400 parks on April 21, 2018 for free.

While the majority of the NPS's parks are free year-round, they'll be waiving admission fees to the more than 100 parks that normally require an entrance fee. Which means that you can pay a visit to the Grand Canyon, Death Valley, Yosemite, or Yellowstone National Parks without reaching for your wallet. The timing couldn't be better, as many of the country's most popular parks will be increasing their entrance fees beginning in June.

The National Park Service, which celebrated its 100th birthday in 2016, maintains 417 designated NPS areas that span more than 84 million acres across every state, plus Washington, D.C., American Samoa, Guam, Puerto Rico, and the Virgin Islands.

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environment
How the Planet Has Changed Since the First Earth Day in 1970
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The first Earth Day in 1970 was celebrated with protests, nature walks, concerts, and other activities meant to spark interest and engagement in the planet's well-being. Since then, April 22 has been a day to reflect on our impact on the environment, on broad and individual scales. So just how much has the Earth changed since the first Earth Day 48 years ago? According to this video from the American Museum of Natural History, it's changed a lot, and not for the better.

The world's population has doubled since 1970, from 3.7 billion then to over 7 billion today. While there are more people consuming resources, more resources are also being consumed per person. On average, we're each burning 37 percent more fossil fuel than we were in 1970, eating 60 percent more meat, and taking 495 percent more plane trips. All that consumption adds up to 1.2 trillion tons of CO2 emitted in the past five decades, which contributed to ocean waters warming 1°F and sea levels rising more than 5 inches.

Those numbers look pretty grim, but it isn't all bad news: Humans have also made significant strides toward protecting the environment in that same period, including passing the Endangered Species Act, designating protected marine areas, and signing international agreements to reduce greenhouse gas emissions across the globe.

People are also more aware of what can be done on a personal level to reduce their carbon footprint. For tips on how to be greener this Earth Day, check out our list of eco-friendly habits.

[h/t American Museum of Natural History]

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