WMOD00522

• Title: Projected Impacts of a Very Large Windpower Complex
• Date: 9/26/1978
• Weather Modification - Doc Type: Report

A full assessment of bird kills would have to address the question
whether these kills might threaten the survival of a healthy breeding
popula tion of any species, This assessment Yl'ould require some knowledge of
the size of the population and the attrition to which it is subj,ect from
natural and other manmade hazards. For examplet even though the severe
winters of 1976-1977 and 1977-1978 in Ohio reduced the population of wrens
to a small fraction of the normalt the breeding rate is such that the
species was expected soon to refill its normal ecological niche. The Fish
and Wildlife Servicet Department of the Interiort has been quoted as estimat-
ing that 100 million waterfowl migrating through the Great Plains flyway
suffer about 50 percent attrition annually. The actual hazard of the
projected windfarms would be affected by site-specific factors such as the
relationship of the site to migration routes of particular species, Mnst of
these matters must remain as speculations until further experience has been
gained,

Means of mitigating the hazard of bird collisions have bl:en investiga-
ted by the Federal Aviation Administration and by the Department of Defense
as they relate to operation of aircraftt and discouraging flocks of birds
that become a nuisance in cities has long been a pesky problem. Deterrents
like flashing lights and amplified distress calls have had some success.
Whether bird kills at windfarms might be mitigated by such means remains
speculative.

In the course of their huntingt most birds of prey pass through
the elevations above ground at which windpowered generators operatet but
except for owls they are active only by daylight, Because of their keen
eyesight and extremely maneuverable flight, it is doubtful that they would
often fall victim to the moving blades, The wide separation of individual
machines t furthermore, would probably not appreciably increase the proportion
of the windfarm area denied them as hunting territory. Howevert assumptions
as to impacts on these birds remain to be verified.

Further study of particular nesting, migratory, and predatory
bird species in the area would be necessary to determine whether a risk of
significant adverse impact might exist.

c. Noise - Recognition of noise pollution as an environmental
factor has grown rapidly in recent years. People with the wind-machine
experience have not considered noise to be a potential problem even in
relatively populous areas 13. ' In the projected settings, no basis has
been identified for expecting an adverse impact from noise.

d. Wireless Communications. - A study of broadcast interference 14
found limited interference with the video channel of television reception
that was worst on the highest frequencies; that is to say, the upper UHF
channels, No interference with FM reception or with the audio channel of
television signals was observed.

The television interference arose from specular reflection from
metal wind-machine blades acting singly, If the television station were
imagined as the sun and the metal blades as polished reflectorst the inter-
ference would correspond to flashes of reflected sunlight seen at the
receiving antenna. For any given azimuthal position of the wind machine and