I know that it is a tragedy when a person wants to check Twitter on her phone, and the service sucks and — aaaaahhhh — now she is bored. Bored, bored, bored, and AT&T is the worst, and why didn’t you wait for the Verizon iPhone? Luckily for bored humans, there are 84,000 communications towers in North America intended to forestall this type of angst. Unluckily for birds, these 84,000 communications towers in North America often kill the birds as they are migrating each year.

The University of Southern California put a number on this massacre and it is large: 7 million bird deaths each year.

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As context for that, the university offers this figure: Exxon Valdez is responsible for only 250,000 bird deaths.

The worst towers are the tall towers — the 1.6 percent of towers that go above 900 feet. That’s still a fair number of towers (more than 1,300). But these skyscraping towers alone kill about 4.5 million birds every year. It’s not actually the towers that tend to kill the birds, but the cables that hold them up.

Update: Oops, missed the caveat that these aren’t generally cell phone towers — they’re TV and radio towers. Point still stands, I’d say: birds are dying so humans aren’t bored.