[snip]
> Basslink perturbations of the magnetic field and hence bird navigation
> should be limited to its immediate vicinity - say within ~100m of the
> cable. Its hard to see why this perturbation should have a significant
> impact when there is existing natural variation in the magnetic field
> from geological causes of greater magnitude.
On this subject, there are signs that the Earth's magnetic field may be
undergoing one of it's regular magnetic field reversals. From
New Scientist, "Anomalies hint at magnetic pole flip":
http://www.newscientist.com/news/news.jsp?id=ns99992152
The article states: "The last reversal happened about 780,000 years ago,
over a period of several thousand years." This is well within the fossil
record for birds so any adverse effects on migratory birds should be
visible, but I'm not aware of any evidence of this or any other magnetic
field related problems e.g. increased cosmic radiation. This isn't
really surprising since magnetic fields are probably only significant
when visual cues are not available.
Another article of interest, "Magnetic fields signal refuelling stops
for migrating birds":
http://www.newscientist.com/news/news.jsp?id=ns99991504
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Paul Taylor Veni, vidi, tici -
I came, I saw, I ticked.
Birding-Aus is on the Web at
www.shc.melb.catholic.edu.au/home/birding/index.html
To unsubscribe from this mailing list, send the message
"unsubscribe birding-aus" (no quotes, no Subject line)
to
|
