Suspected road salt poisoning in Bohemian Waxwings, Bombycilla garrulus (Aves: Passeriformes: Bombycillidae)

Abstract

The effect of road salts on wintering birds is a serious but recently underreported environmental threat. With the example of Bohemian Waxwings, Bombycilla garrulus, it is discussed that seemingly straightforward explanations, e.g. window collisions, may obscure the primary cause of wrecks. Therefore I argue that birds, particularly those with high daily water intake like the frugivorous waxwings, may consume high concentrations of dissolved road salt with melt water. A review of literature made apparent that salt overdoses lead to aberrant fl ight behaviour and impaired manoevrability, which render them likely to fall victim of road traffi c or to collide with windows. It is discussed that undetected road salt poisoning might explain many ambiguous cases of lethal accidents of wintering birds in urban surroundings.