Studies of Birds Killed in Nocturnal MigrationTordoff, Harrison Bruce
Science
Studies of Birds Killed in Nocturnal Migration
Tordoff, Harrison Bruce
Birds -- Migration
Considerable interest has been occasioned in recent years in the
eastern United States by large-scale accidents to night-migrating
birds. Most accidents have occurred in the autumn. The widespread
adoption by airports of an instrument called the ceilometer, which
measures the height of cloud ceilings by reflecting from them a
high-powered beam of light, has proved under certain conditions to be
catastrophic to night-flying birds. Among the recent reports of such
accidents are those of Spofford (1949) and Laskey (1951) for
Nashville, Tennessee, Howell and Tanner (1951) for Knoxville,
Tennessee, and Lovell (1952) for Louisville, Kentucky. Recently
Howell, Laskey, and Tanner (1954) reviewed ceilometer "tragedies"
without being able to determine the exact reason for their lethal
effectiveness. Less publicized so far have been mass collisions of
birds with another class of obstacles, tall radio and television
towers. These slender towers, usually 500 to 1000 feet tall, are
increasing rapidly in numbers and there is reason to suppose that they
will take a correspondingly larger toll of bird life.
Notice has long been given by ornithologists to mass destruction of
birds by more conventional solid obstructions to passage, and
newspapers occasionally mention birds killed at such well-known points
as the Washington Monument and the Empire State Building.
Seventy-five years ago, J. A. Allen (1880) published the results of
questionnaires circulated by William Brewster to lighthouse keepers.
Brewster himself (1886) described destruction of birds at a lighthouse
in the Bay of Fundy, paying keen attention to behavior of the birds
and the exact conditions under which nocturnal flight and accidents
occurred. The subject also received attention in several countries
across the Atlantic. Destruction of birds at Irish lighthouses was
carefully noted over a period of years and the results were published
periodically, culminating in R. M. Barrington's massive report (1900)
which remains in some ways the most thorough of its type.
Public-domain text, read in full here on John Shaqi.
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