The destruction of migratory birds by their striking lighthouses,
light ships, tall bridge piers, monuments, and other obstructions
has been tremendous. Beams of the lanterns at light stations have
a powerful attraction for nocturnal travelers of the air. It may
be likened to the fascination for lights that is shown by many
insects, particularly night-flying moths. The attraction is not so
potent in clear weather, but when the atmosphere is moisture laden,
as in a heavy fog, the rays have a dazzling effect that lures the
birds to their death. They may fly straight up the beam and dash
themselves headlong against the glass, or they may keep fluttering
around the source of the light until exhausted, and then drop
to the rocks or waves below. The fixed, white, stationary light
located 180 feet above sea level at Ponce de Leon Inlet (formerly
Mosquito Inlet), Fla., has caused great destruction of bird life
even though the lens is shielded by wire netting. On one occasion an
observer gathered up a bushel-basketful of warblers, sparrows, and
other small passerine birds that had struck during the night. The
birds apparently beat themselves to death against the wire or fell
exhausted to the concrete pavement below, frequently to be destroyed
there by cats or skunks. Two other lighthouses at the southern end
of Florida, Sombrero Key and Fowey Rocks, have been the cause of
a great number of bird tragedies, while heavy mortality has been
noted also At some of the lights on the Great Lakes and on the coast
of Quebec. It is the fixed white lights that cause such disasters
to birds, as the stations equipped with flashing or red lights do
not present such strong attractions. That it is not a mere case of
geographical location has been demonstrated, for it is observed that
when fixed white lights have been changed to red or flashing lights,
the migrating birds are no longer endangered. At some of the light
stations in England and elsewhere, shelves and perches have been
placed below the lanterns to afford places where birds can rest until
they have overcome their bewilderment.
For many years at the National Capital, the Washington Monument,
although unilluminated, caused the destruction of large numbers of
small birds, due apparently to their inability to see this obstacle
in their path, towering more than 555 feet into the air. One morning
in the spring of 1902 the bodies of nearly 150 warblers, sparrows,
and other birds were found about its base. Then, as the illumination
of the city was improved and the Monument became more visible at
night, the loss became steadily less, until by 1920 only a few birds
would be killed during an entire migration. On November 11, 1931,
however, as part of the Armistice Day celebration, batteries of
brilliant floodlights grouped on all four sides about the base of the
Monument, were added to the two searchlights already trained on the
apex, so that the lighted shaft probably corresponded in brilliancy
to a very low magnitude lighthouse lantern. Airplane pilots have
ventured opinions that on a clear night it could be seen for 40
miles. It is certain that there is an extensive area of illumination,
and on clear, dark nights when the nocturnal travelers seem to fly at
lower altitudes, many of them are attracted to the Monument as to a
lighthouse beacon, and wind currents prevent a last-minute avoidance.
During the fall migration of 1932 more than 500 warblers, vireos,
thrushes, kinglets, sparrows, and others were killed. In 1933 the
mortality was less, but the Monument at times still remains a serious
menace to birds during migration.
When the torch on the Statue of Liberty in New York Harbor was kept
lighted, it caused an enormous destruction of bird life, tabulations
showing as many as 700 birds in a single month.