Deadly gastroliths: Eurasian siskins carduelis spinus poisoned by road salt grains

Abstract

We describe a case of winter mass mortality of Eurasian Siskins Carduelis spinus caused by large road salt grains that birds apparently had mistaken for potential gizzard stones (gastroliths). Clinical evidence revealed acute salt intoxication as the cause of death. We recommend using only small-sized salt grains (<2 mm) for de-icing roads in order to save wintering birdlife from a potentially hazardous substance.