Thursday, May 13, 2010

Tampering With Evolution

"All it takes to wreak havoc in a colony of common murres is one bald eagle.  Gulls spot the eagle from a distance and sound the alarm, and the murres nesting on the cliff bob their heads nervously.  As the big rapter swoops down, the stocky black-and-white seabirds flee, leaving their eggs and chicks behind.  Gulls and crows then quickly move in and gobble as many as they can....

In the 1960s, the bald eagle nearly became extinct; widespread DDT use had thinned its eggshells.  Once the pesticide was banned in 1972 and conservation efforts increased, populations rose dramatically, and the bird was removed from the federal endangered species list in 2007.  But human activity had altered the raptor's habitat in many ways - development encroached, available food sources shifted, the populations of some species rose while others declined.  The bald eagle was brought back in the hopes of helping restore ecosystem balance, but wildlife managers lacked information about what that balance originally looked like.  Now, along the Pacific Northwest coast, reports abound about eagles creating havoc among cormorants, murres ,and other seabirds.  Biologists are at a loss about what, if anything, to do about the charismatic troublemaker they worked so hard to bring back."

This excerpt, from the March 2010 issue of High Country News, represents the opening two paragraphs of a very important story about the complex relationship among species, and what happens when humans experiment unintentionally (e.g. DDT) and intentionally (conservation measures) with evolution.  Even if you're more apt to read about politics than wildlife, I encourage you to read the remainder of this story, written by Isabelle Groc, for its elucidation of the complicated relationship we have with the planet's wildlife.

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