Utility installs insulators to 'eagle proof' power lines
Work is an attempt to stop more electrocutions of famous Decorah eagles
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DECORAH — The overflight Friday of a brilliantly plumed bald eagle seemed almost like a benediction as workers below installed protective devices on an electricity transmission line that last year killed one of the world-famous Decorah eagles.
While it’s probably impossible to eagle-proof an electrically charged transmission line, safeguards installed last week will make future electrocutions much less likely, said Tom Petersen, communications director for ITC Midwest, whose 69,000-volt line near Decorah was the source of the current that killed the young eagle in July 2014.
“We really appreciate their thorough and thoughtful response to the accidental death,” said John Howe, who succeeded the late Bob Anderson as director of the Raptor Resource Project, whose nest camera has showcased the Decorah eagles for millions of Internet viewers.
ITC Midwest took the eagle’s death seriously and responded in a way that sets an example for power companies, said Amy Ries, a member of the raptor group’s board of directors.
Before his sudden death in July, Anderson was growing increasingly concerned about the electrocution of eagles on power lines and thought they presented a greater threat to eagles than wind turbines.
Two Decorah eagle chicks hatched in 2012 and two more hatched in 2014 were found dead beneath power lines.
“We consider the project an investment in protecting an extremely valuable environmental and educational resource — the Decorah eagles,” Petersen said.
After consulting with Anderson and with U.S. Fish and Wildlife Service personnel, ITC Midwest, which operates 6,600 miles of transmission lines, put custom-designed and fabricated insulators on all three current-carrying lines around 27 utility poles in a flight corridor stretching from Trout Run, the site of the Decorah eagles’ nest, back to the southeast.
Each insulator covers 10 feet of line, 5 feet on each side of the utility pole.
Electrocution occurs when a bird perches on an electrically charged wire and then completes the circuit by touching, typically with a wing, some point of ground such as the pole, a conductor or another wire.
“It’s a pretty simple concept: Just cover the wires,” said ITC project engineer Mike Ryan.
Earlier this year, to reduce the likelihood of birds flying into the power lines, ITC Midwest crews also affixed highly visible flight diverters on the lines in the heart of the Trout Run corridor.
The most recent electrocution occurred in March when a 2014 hatchling, a female nicknamed “Four,” was found dead beneath an Alliant Energy utility pole between Keota and Harper in rural Keokuk County.
Within weeks, Alliant crews retrofitted a dozen utility poles in the area with triangular plastic devices on the crossarms to discourage perching and sections of plastic insulation on the wires themselves to decrease the likelihood of a bird contacting two charged wires at once.