184 | Chapter 10
stretch across those valleys from one misty ridge to another. Alas, the
peace of the tropical night is sometimes broken when birds slam into
lines.^4
To mitigate this problem, good information on the number and spa-
tial distribution of collisions is needed. Searching for downed birds in
the thick vegetation bristling out of near- vertical terrain under the lines
is beyond impractical. But pioneering work has shown that modern
song meters may help identify collisions. Set beside a power pylon, the
meters record hundreds of hours of sound onto a memory disc. Mostly
the recorded sound is the rustle of the Hawaiian wind, but occasionally
it is the sound of a bird hitting the wire. Since nobody can listen to the
playback of sighing wind for hundreds of hours, and remain awake, the
trick is to develop computer software that will pick out the sound of a
bird collision from the prevailing background noise. Programmers are
currently addressing this very problem. In due course, such work may
be a precursor to pinpointing factors which make particular lines more
or less dangerous and, eventually, to developing solutions.
When in transit between their colonies and their feeding areas, more
or less far offshore, seabirds frequently gather en masse. Great Shear-
waters assemble in their hundreds of thousands off Nightingale Island
adjacent to Tristan da Cunha. Below the famous Bempton Cliffs of
Yorkshire, England, thousands of Common Guillemots and Razorbills
gather to rest, wash, and preen. It defies belief that jet skiers should
choose to open the throttle and rampage through the flocks – but they
do.^5 Since these areas close to colonies fall within national territorial
waters, the passage of the necessary conservation legislation is not hin-
dered by international issues.
***
Most seabird species spend the great majority of their time at sea, often
far offshore and out of sight of land. Out of sight does not mean out
of danger. Chemical pollutants reached Antarctica from the industrial
world decades ago. Oil slicks and the associated images of birds’ strug-
gles amid oily slime are simply horrible. Corralled by the circulating cur-
rents of the central North Pacific, the so- called Great Pacific Garbage