Definition:

(noun) A mass mortality event when otherwise healthy birds mysteriously die, usually with large numbers of deaths occurring suddenly in a short time span. A die-off may affect just one bird species, several related species or all birds in a specific region, and the numbers of birds affected can range from a few dozen to several thousand birds. While any bird species can be affected by a die-off, birds that are most frequently affected tend to travel in large flocks, such as waterfowl, blackbirds and starlings.

There are many causes of bird die-offs, including natural events such as diseases, storms or predators as well as artificial causes such as pollution and trauma after colliding with buildings, power lines or wind turbines. In some cases the events are preventable, but in others they are a natural occurrence. Conservationists study die-offs to determine if larger environmental factors are at work and to judge how these events impact the survival of threatened bird species.

While large die-offs generally get significant media attention, small incidents involving a few dozen birds are quite common and generally are not cause for concern. When threatened or endangered bird species are affected, or if the bird fatalities reach large numbers of birds or multiple species, more attention may be necessary to ensure the die-off is not critical.

Photo – Dead Bird © Eric Schmuttenmaer

Pronunciation:

DYE OFF

Also Known As:

Aflockalypse (slang)