I've been following the exchanges about wind turbine impacts to
wildlife and was puzzled about the participation of Mr. Tom Gray, who
is the communications director and deputy executive director of the
American Wind Energy Association - a "national trade association that
represents wind power plant developers, wind turbine manufacturers,
utilities, consultants, etc." Apparently Tom makes a habit of
monitoring the list-servs of bird groups throughout the region
(nationally?) in order to inject info or views favorable to the wind
industry. I trust others are aware of Mr. Gray's role in this
discussion, and hopefully note his bias when considering the
information he selectively but generously provides.
His latest post to VA-Birds continues the long-standing efforts of
avian consultants hired by developers of "industrial" windplants to
dismiss or minimize concerns regarding wildlife impacts due to siting
of very tall wind turbines along Appalachian ridges.
Unlike in the west, the vast majority of birds likely to be killed at
wind turbines in the east are neotropical migrants - which pass through
our region mostly at night. Many of these species are already under
severe pressure due to loss and fragmentation of breeding and wintering
habitat. Studies show that few of these kinds of birds are caught by
cats or are hit by cars. Unfortunately, pro-wind advocates like to
cite high bird mortality totals owing to other human structures while
perhaps ignoring the overarching concern that cumulative impacts to
these birds are additive, not relative.
While Mr. Gray is correct in his assertion that it is only a "theory"
that birds might be channeled by prominent ridgelines such as found in
VA, he fails to mention that this theory is actually supported by data
- whereas the opinions of the wind industry's paid consultants have no
data to support their self-serving claim that nocturnal bird migration
is not influenced by mountainous terrain.
Dr. Paul Kerlinger is the principal avian migration consultant hired by
wind energy developers here in the east. In numerous "Avian Risk
Assessment" reports assessing wildlife impacts of proposed windplants
in MD, PA and WV, Dr. Kerlinger routinely has dismissed concerns about
harm to nocturnal migrants due to siting of extremely tall wind
turbines atop prominent ridgelines (claiming night migrants are not
known to follow ridges at night). However, he has never studied the
phenomenon of nocturnal avian migration in this region, and was not
aware of (or failed to disclose the knowledge of) research that
indicated ridges can indeed channel the movements of songbirds during
night-time flights.
The fact that nocturnal migrant songbirds fly along and over ridge
crests has been documented in the Central Appalachians for over 20
years, as the following excerpt from published research involving the
region's first radar monitoring demonstrates:
"The patterns of migration detected in a mountainous area suggest that
nocturnal migrants may well be influenced by topography. For the two
nights we observed [Oct. 4 and 14, 1980] it appears that birds on the
upwind side of the ridge were moving along the ridge, birds at the
crest were moving along and over the ridge and few birds were found at
low altitude on the downwind side of the ridge." Source: Seilman, M.
S., L. A. Sheriff, and T. C. Williams. 1981. Nocturnal migration at
Hawk Mountain, Pennsylvania. American Birds 35:906-909.
Furthermore, mountain ridges have been found to orient and concentrate
night-migrating birds in Europe and elsewhere in the Appalachian
Mountains of the United States. This following paper was published:
Williams, T.C., J.M. Williams, P.G. Williams, and P. Stokstad. 2001.
Bird migration through a mountain pass studied with high resolution
radar, ceilometers, and census. Auk 118:389-403;
and it concluded -
Our observations and those of Bruderer and his coworkers [involving
the Alps] indicate that broadfront migration should not be assumed for
the passage of avian migrants over mountainous areas. That is
important for evaluation of structures such as wind-powered electrical
generators or communication towers on ridge lines. Although our
studies were not designed to observe concentrations of migrants at
topographical features, reaction of migrants to topography that we did
observe suggested such concentrations during favorable and unfavorable
conditions. Concentrations could result either as birds moved along a
corridor, such as a pass or ridge line, or they could result from birds
moving up and over a ridge meeting migrants already at that altitude
and thus producing large numbers of birds a few tens of meters above
the ridge summit. Our ceilometer observations of large numbers of
birds near crests of ridges are particularly relevant in that regard.
Consequently, Dr. Kerlingers notion that nocturnal migrant songbirds
do not follow or fly along Appalachian ridges at night is not
corroborated by either of the two investigations of this phenomenon
published to date. Furthermore, the observations by Williams et al.
clearly show potential for concentrations of nocturnal migrants at
altitudes and locations where wind turbines are being planned or
erected. And the large bird kill at the WV windplant is indeed
evidence that wind turbines do pose a collision hazard for nocturnal
migrants.
Readers interested in seeing the distribution of communication towers
in VA (or other states) should check the following website:
http://www.towerkill.com and click on the state's outline on the map of
the US. Few communication towers are identified in Highland County
whereas proposals exist for many hundreds of 400-foot tall wind
turbines to be erected in this locale.
Mr. Gray wishes to discount the importance of the 30 birds killed in
one foggy night in late May 2003 at the WV windplant (all warblers and
other neotropical migrants) - which comprised the largest wildlife
mortality event ever recorded for a windplant anywhere in the world
(until over 130 migratory bats were killed during a few days in August
at the same industrial facility). However, it's very important to
recognize that the number of birds and bats found at the WV windplant
reflect only the carcasses found during once-a-week inspections of 44
wind turbines located in very rocky terrain that is difficult to
search, particularly when looking for small birds or bats. In
addition, the detection of the large songbird kill at the the WV
windplant was due to turbine maintenance workers who observed a bobcat
feeding on the bird carcasses and reported this to the graduate
students hired to document the avian mortality of this facility.
So the number of bird carcasses found for the May mortality incident,
and for this entire facility in 2003, would likely be only a small
fraction of those that were actually killed. Other bird mortality
studies have documented that up to 80% of carcasses disappear within 24
hours of hitting the ground. If scavengers are removing carcasses
rapidly, the ratio of number carcasses found to number actually killed
could be 1:10 or possibly 1:100.
Even if only 10-20 birds are killed on average at each turbine per
year, this would add up to a major cumulative impact should the goal
become reality that 20% of our region's electricity were generated by
wind turbines. For VA alone, the 20% goal would require over 4,000
turbines to supply current demand - but that high number could double
before 2025 to maintain this percentage since VA's demand for
electricity is increasing at an annual rate of 3.1%.
The real problem for wind energy advocates is to show how this
alternative energy source can reduce future adverse impacts due to coal
mining and combustion given that our society's profiligate demand for
electricity will likely far outpace the production capability that wind
energy could supply from the entire eastern half of the US.
For bats, the situation appears far worse than for birds in terms of
collision risk with wind turbines sited along Appalachian ridges. The
level of bat mortality from the 44 turbines at the WV facility is on
par with the annual bird kill recorded from all 5,000+ turbines at
Altamont. Although 475 bat carcasses were found, the number likely
killed was in the thousands to adequately reflect removals by scavenger
and detection difficulties. The per turbine rate of mortality for bats
at the WV windplant is 100s of times greater than at Altamont, and a
similar high rate of bat mortality was found at the only other
windplant in the southeast (in the Cumberland Mountains of eastern TN).
Contrary to Mr. Gray's claim, there is NO research currently ongoing to
determine why bats collide with turbines - let alone research that
examines how to prevent collisions. Realistically it could take many
years (if ever) to find an effective deterrent that prevents bats from
colliding with wind turbines. Yet the wind industry is pushing for
siting of turbines with the promise of fixing the "problem" with bats
in the future.
Sadly, the avian mortality research at the WV windplant failed to
follow established protocols, and although the results have not been
officially released yet - they may greatly underestimate the actual
mortality attributable to collision with wind turbines. This research
was funded by the wind energy developer, and overseen by the same
consultant hired by the developer that predicted no significant impacts
would result to avian wildlife. Lets hope that future wildlife studies
at wind energy facilities are performed by researchers that are
objective and independent of financial ties to the developer.
Dan Boone
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