Tuesday, 3 June 2008

Shakespeare, Starlings, and Exponential Growth...

It is an everyday springtime scene across America, you walk out of the house and there it is, the big messy pool of bird droppings. You look to the eves of the house, or the trees next to the driveway, and mentally curse the little winged creatures who left the mess,… but the fault dear Butkus, is not in our trees, but in our Bards… Yep, Blame it on Shakespeare.
Your problem began in a place far, far away, both in time and space. Sometime just before 1600 Shakespeare, apparently conscious of the ability of the starling to mimic the sounds of other birds, was writing Henry IV. Remember that scene? Hotspur plots to drive the king mad by “, I’ll have a starling shall be taught to speak nothing but ‘Mortimer’ “, the name of Hotspur’s in-law whom the King refuses to ransom.
That’s essentially all it took… well, that and a somewhat strange group who operated in America late in the 19th century, the American Acclimatization Society. Their goal was to introduce every bird mentioned in Shakespeare into the US. Keep in mind that Shakespeare names over 600 birds in his works…(honest, I counted) including the starling, and the sparrow… Yep, the one you call a common house sparrow… they are English, …. Not a native at all, and the same people brought them to America. WHY??? Because Shakespeare wrote:

Not a whit, we defy augury. There is special providence in the fall of a sparrow. If it be now, 'tis not to come; if it be not to come, it will be now; if it be not now, yet it will come—the readiness is all. Since no man, of aught he leaves, knows what is't to leave betimes, let be".

Knowing that Laertes is out to kill him, he still accepts the contest, giving himself over to fate......The reference to the sparrow comes from St. Matthew, chapter 10: (29-31) "Are not two sparrows sold for a farthing? and one of them shall not fall on the ground without your Father.(knowing)"

By the way, the augury of which Hamlet spoke refers to predictions from a priest, called an augur, who studied the birds to predict the fates of men.
But I digress, so back to Shakespeare and the bird-brains (oops bird-lovers) of the Acclimation Society. In 1890 and 1891 they released about 100 starlings into Central Park in New York City……and from that motley band, they grew, and flew, and grew some more. By 1960 they had spread coast to coast and were in every county in the 48 United States (I’m omitting those late-comers in Alaska and Hawaii, but I bet Alaska has starlings too. In the 1960’s, they were considered such a threat to the economy of California that there was a mass attempt to exterminate them, killing over 9 million of the birds. There were numerous other attempts to kill them off around the country, especially in agricultural states where they were thought to pose a threat to grain crops. The starlings just scoffed, and went on growing…growing….growing… until today there are 200 Million in North America, (Mr. Bush’s fence and treaties with Canada have not restricted their holidays in both neighboring countries). I read a quote by a Jeffrey Rosen who said, “It isn’t their fault that they treated an open continent much as we ourselves did.”

I did the arithmetic, and even ignoring the millions killed in the fifties and sixties, they grew at upwards of 13% a year. I expect it was actually much faster, and that the growth follows a logistic curve with an upper lever somewhere near the present population. Kill a few million and they will almost immediately repopulate to their present number. But if they can acclimate to a little more heat in the south of Mexico, or the cold north of Hudson’s Bay… they could tack on another 100 million easy.

Eventually, they may create enough pressure on the native American birds, that the “Blue Bird on My Shoulder” will be the only one left. Then New York and Missouri will have to find a new state bird (yes Virginia, the Eastern Blue Bird IS the state bird of Missouri).

By the way, we got our revenge... The English are being ravaged by the American Grey Squirrel.

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