[va-bird] Re: windpower Post article
- From: Tom Gray <tomgray@xxxxxxx>
- To: va-bird@xxxxxxxxxxxxx
- Date: Sat, 27 Dec 2003 17:43:35 -0500
At 10:22 PM 12/26/2003 -0500, LeighTern@xxxxxxx wrote:
Why are windmills so hard on birds? I read the article in the post. I didn't
find it very helpful. It didn't explain to me how or why windmills are more
dangerous than any other tall structure ..........skyscrapper, radio towers ,
Cell phone facilitators etc etc.
W
William Leigh
Leightern@xxxxxxx
Winchester VA
In general, they aren't. At most wind sites, including Altamont, the total
number of birds killed by collisions is probably about what could be
expected if stationary structures the same height were installed.
However . . . at Altamont, the TYPE of birds being killed is unusual, in
that it includes many raptors (golden eagles, red-tailed hawks, American
kestrels, burrowing owls). I think in general, researchers believe this is
because
(1) Altamont Pass has a very abundant prey base of ground squirrels
and pocket gophers;
(2) It also has very high, year-round, raptor use;
(3) The wind turbines are older, smaller machines (most installed prior
to 1985) that rotate faster and are spaced more closely together than
modern, state-of-the-art turbines; and
(4) Raptors often collide with the turbines when pursuing prey or
flying rapidly along the contours of the ground (i.e., they aren't
looking ahead for obstacles).
While more raptors are also killed at some other wind sites than
might be expected from their percentage of the overall bird population,
the absolute numbers are far lower than in Altamont Pass--about 1/10
as many per unit of rotor swept area.
Tom Gray
American Wind Energy Association
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