The effects of light characteristics on avian mortality at lighthouses

Jones, J. and Francis, C. M. 2003. The effects of light characteristics on avianmortality at lighthouses. – J. Avian Biol. 34: 328–333.The generation of artificial light by human activity can have far-reaching detrimentalimpacts upon a wide variety of organisms. A great deal of attention has been paid towell-lit buildings, television towers, and communication towers as sources of mortal-ity for nocturnally migrating songbirds. However, despite being among the firsthuman structures known to generate migratory bird kills, little is known about thecurrent impact of lighthouses on birds, or the impact of light design. We examinedthe impact of a lighthouse on nocturnal avian migrants at Long Point, Lake Erie,Ontario, Canada. From 1960–1989, mean annual kills were 200 birds in spring, and393 in autumn, with kills of up to 2000 birds in a single night. In 1989, the LongPoint lighthouse was automated, with a simultaneous change in beam characteristics– the new beam is narrower and less powerful. This change brought about a drasticreduction in avian mortality at the lighthouse to a mean of only 18.5 birds per yearin spring, and 9.6 in autumn from 1990–2002. Our results highlight the effectivenessof simple changes in light signatures in reducing avian light attraction and mortalityduring migration.