Radar Studies Show Proposed Wind Farms Unlikely to Impact Migratory Bird Populations
Data Totally Refutes Repeated Claims by Dan Boone, former Conservation Chair of the Maryland Sierra Club
By Mike Tidwell
Maryland Sierra Club Member
Director, Chesapeake Climate Action Network
October 4, 2005
Recently completed radar studies and avian mortality data show that there is little likelihood that five proposed wind farms in western Maryland and neighboring Appalachian states will have any impact on migratory songbird populations. The studies strongly reject the hypothesis — suggested repeatedly by Dan Boone, Maryland Sierra Club Conservation Chair — that a significant percentage of migratory songbirds travel along ridgelines at low altitudes and so are at great risk of striking commercial windmills in large numbers.
At many public venues – including official testimony at a state hearing — Boone has attacked proposed wind farms by repeating purportedly scientific claims that “large flocks of [nocturnal] migrants follow the highest mountain ridges” (12/6/02 testimony before the Md Public Service Commission). But the new studies reveal that only a small percentage of migratory birds actually follow the topography of mountaintop ridges and that the vast majority of all migrating birds fly well above the tops of existing or proposed wind farm towers.
"Based on the existing data we now have, there is little likelihood of any impact on populations of migrating songbird populations,” said Dr. Dale Strickland, a specialist who conducted a fall 2003 radar study at Mount Storm, West Virginia. The study is one of five radar studies whose data are now available to the public.
Strickland, who has 30 years of ecological research and wildlife management experience, designed and managed the Mount Storm study for Western EcoSystems Technology, Inc. The study used mobile marine surveillance radar (X-band, 12 kw) in horizontal and vertical modes. The radar systems monitored the autumn migration of birds across the full area of the proposed Mount Storm wind farm.
The study results are consistent with similar studies conducted since 2002 at proposed wind farm sites in Martindale, Pa, Casselman, Pa., Dan’s Mountain, Md., and Jack Mountain, WV. At the Mount Storm site in northeastern West Virginia, Strickland found that 84 percent of all birds and bats flying over the site flew above 400 feet (the height of a typical modern windmill). And only a small percentage of the birds followed the ridgeline where the proposed turbines would be located. Wind power critics had been concerned that ridgeline-oriented flight would result in serial collisions with turbines.
"The fact that the birds fly over the ridges in a mostly ‘broad front’ migration instead of along the ridges is good news,” said Gerald Winegrad, former vice president of the American Bird Conservancy and a retired Maryland Senator from Annapolis. “It’s certainly good news in terms of wind power and avian mortality.”
Based on bird-strike data collected at a nearby wind farm already in operation in West Virginia, Strickland’s study team calculated that — of the small percentage of birds flying below 400 feet at the Mount Storm site — only .016 percent would strike the windmills during fall migration. This works out to about four birds per turbine per year. (see study at www.west-inc.com/mount_storm_final.pdf).
A sixth Appalachian radar study has been completed at a proposed wind farm in Garrett County, Maryland but authorization to release the data has not been given by the four Maryland residents who intervened in the wind farm’s permitting process. Although deviations in bird behavior are possible, Strickland and other avian specialists who’ve examined radar data from across the region are highly confident that the Garrett County study area will reflect bird behavior patterns similar to the other nearby study areas, meaning low probability of impact on migratory bird populations.
“Surprises are possible…but given all the data gathered at nearby study sites, it seems unlikely that the (Garrett County) data would be much different,” said Winegrad.
It’s unclear where the hypothesis of concentrated, low-level migration of songbirds along ridgetops actually originated given the total lack of study data to support it. Strickland believes the hypothesis may have emerged from the relatively large numbers of migrant birds that have been captured and banded for various avian studies in the past in this region of central Appalachia.
“The assumption seemed to be that these birds were near the ridgelines in apparently concentrated numbers to catch wind updrafts that would allow them to follow the ridgeline during migration while doing less work,” said Strickland. “But with the radar data, we now know the birds don’t in fact concentrate along the ridgelines. It just seemed that way to some people.”
The six radar studies were conducted at an estimated cost of over half a million dollars to the wind power industry. Neither Strickland nor Winegrad were aware of any avian impact studies ever underwritten by natural gas or coal companies in Appalachia. Yet the latter have totally obliterated 490,000 acres of Appalachian mountain forest land just in the last 12 years through a process called 'mountaintop removal' to mine coal.
A long-awaited study on bats and windmills will also be released soon. Some scientists and wind industry officials have expressed optimism in recent months that the issue of bats being attracted to certain windmills might be mitigated through the use of a high-frequency acoustic deterrence at the wind farms.
My alarm went off at 6:00 am.
