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More bird numbers

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7/18/2008 -- More bird numbers

American Robin Reading the last blog entry again, I reviewed the book "The world without us" and did some math. In chapter "Wings without us" are some numbers given of birds becoming victims of human activities. I was hesitant to put any numbers in the blog - for one, they really are estimates only; and also they get so BIG that they seem quite overstated.
However, other sources I checked showed similar numbers, e.g. from the US Fish and Wildlife Service [1MB PDF!] . Long story short, here is my rough number of birds getting killed "inadvertently" per year (US only): 2,500,000,000.

Note that this represents birds being killed not for food or any direct need, but e.g.
· accidentially (car collisions, 60 million)
· for our convenience (on communication towers, 30 million)
· for shiny high-rises (glass facades and skyscraper lights, 500 million)
· for having some cute diversion (roaming cats, up to 1.5 billion)
· or just for fun and recreation (sport hunting, 120 million).

I did not dare to put a number here which is owed to loss of habitat. This definitely would get the top spot even before the cats.

Impressive anyway, right? If you take some books writing on this topic, you'll read about a "deepening silence" around us (Alan Weisman), and that "[these] days, the woods are a pretty quiet place" (Bill Bryson).

I'll spare the preachy paragraph which was here before.

We'll keep you updated on our two backyard bluebirds. If you happen to have a domestic cat in the South Bend area, I kindly request you to keep him/her inside .

Comments on this blog post:

081025 213429 from admin [wk]

Some additional remarks on the occasion of an article in the National Geographic of November. On page 119 you'll find an illustration of a somewhat shocking "exhibition" of birds being killed on glass windows and man-made structures.
Once more it should be mentioned that the figures in the blog above are rough estimates only. The numbers vary immensly, especially for birds being killed by (feral and domestic) cats. We felt backed up by the website of FLAP , mentioned in the NG article, which states a similar number like our "up to 1.5 billion" (it says "between 4 and 5 million birds in the US [daily]").
But for further reference, here are two more sources - lower and higher estimates:

"Estimates for how many birds cats kill in the United States vary (...) widely. The lowest estimates are around 100 million and go up to the 2.5 billion, though the consensus seems to hover around half a billion." (Opinion "Kill the Cats" in National Review Online )

"(...) a conservative estimate is that 1 in 10 cats kills a bird a day - this would yield a daily toll of 4.4 million birds - or 1.6 billion cat-killed birds in the US each year (...) Alley Cat Allies estimates that there are 60 million feral cats in the United States. Combining feral and domestic cat predation, it is estimated that more than 3 billion birds are killed annually." (One of more references from an Article about "Cats and Birds" )

In the end, all these numbers should not distract from what we wanted to say. It seems consensus, that cats and loss of habitat are the biggest threats to native birds (and bird species for that matter). And that's just one way we run down the resources of this planet.

130131 213727 from admin [wk]

Another guestimate, read on NPR's website: "We estimate that cats kill somewhere between 1.4 and 3.7 billion birds a year (...) And even though the new numbers are much higher than anything calculated before, he thinks they're in the right ballpark (...) We're pretty confident (...) We felt like we only used the best studies out there. We eliminated studies that had small sample sizes or were only conducted for short durations. And we eliminated studies that had really, really high estimates, or really, really low estimates. So we tried to be as conservative as possible."

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