OK guys, I'll take a poke at this too.... As a long time ham and
professional wildlife biologist, I can tell you from personal experience
that tall communication towers are lethal to songbirds, and in massive
quantities. On one occasion, I picked up a heaping full bushel of
neotropical migratory songbirds (warblers, thrushes, orioles, tanagers and
others) under the nearest TV tower in Lansing Michigan, near the MSU campus.
Tall towers continue to kill as many hundreds of thousands of migrating
songbirds as they move through Central America, Mexico, the US and Canada
during both spring and fall migrations. Exhaustion only seems to be a factor
on foggy nights, when the birds become confused by the lighting. Otherwise,
it's mainly direct strikes against the tower itself and the numerous guy
lines that each tower needs. Nearly all songbirds migrate at night (tough to
avoid what you can't see) so most of the fatalities are between dusk and
dawn. The recent addition of a jillion cell phone towers adds to the
carnage. One publication states:
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"Lighted communication towers turn out to be one of the more serious
problems for birds, especially for migratory species that fly at night. One
study began its conclusion with, "It is apparent from the analysis of the
data that significant numbers of birds are dying in collisions with
communications towers, their guy wires, and related structures." Another
report states, "The main environmental problem we are watching out for with
telecommunication towers are the deaths of birds and bats."
This is not news, as bird collisions with lighted television and radio
towers have been documented for over 50 years. Some towers are responsible
for very high episodic fatalities. One television transmitter tower in Eau
Claire, WI, was responsible for the deaths of over 1,000 birds on each of 24
consecutive nights. A "record 30,000 birds were estimated killed on one
night" at this same tower. In Kansas, 10,000 birds were killed in one night
by a telecommunications tower. Numerous large bird kills, while not as
dramatic as the examples cited above, continue to occur across the country
at telecommunication tower sites.
The number of telecommunication towers in the U.S. currently exceeds 77,000,
and this number could easily double by 2010. The rush to construction is
being driven mainly by our use of cell phones, and to a lesser extent by the
impending switch to digital television and radio. Current mortality
estimates due to telecommunication towers are 40 to 50 million birds per
year. The proliferation of these towers in the near future will only
exacerbate this situation. "
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The mechanisms involved in migration by various species remain poorly
understood, whether magnetic fields or celestial navigation (night) or light
polarization, landmarks, magnetic fields, regional low frequency sounds or
other means (day), most migratory methods seem to lead massive flocks of
individual or mixed species along "ancestral" migration routes. When we put
up a tall tower, they fly into it. The addition of many new towers to the
additional losses from constant habitat loss result in a marked, long-term
decline in migratory songbird numbers. I don't think that most ham towers
are tall enough to contribute significantly to bird strike losses, though
certainly some occur. Perhaps the switch to commercial satellite radio, TV,
voice and data comms and other communications will bring the day when the
iron comes down and the skies are clear again.
If you want to see something impressive, start watching Doppler Radar
reports from the Cuba-Florida-Georgia region starting in early April through
early May, and see hundreds of millions of songbirds lift off as darkness
falls each evening and head north. On one hand, it's a pretty stunning radar
report; on the other hand, it shows us how finite songbird populations are.
Bob Hinkle, KK8ZZ
Solon, Ohio 44139
Grid: EN91gj
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