Short-term effects of tartar emetic on re-sighting rates of migratory songbirds in the non-breeding season

Abstract

Forced regurgitation by oral administration of tartar emetic has been used frequently to examine avian diets because it does not require killing birds directly, but indirect (delayed) mortality by this technique is not well studied. We examined the effects of tartar emetic on re-sighting rates of insectivorous migratory songbirds in Jamaica during the non-breeding season. The re-sighting rate of Black-throated Blue Warblers (Dendroica caerulescens) experimentally treated with tartar emetic was significantly lower than for control birds. The re-sighting rates of American Redstarts (Setophaga ruticilla), Black-and-white Warblers (Mniotilta varia), and Prairie Warblers (Dendroica discolor) treated with tartar emetic were also lower than those of birds that were banded and released without treatment. Pre-release mortality rates were low (<3%), but two treated Black-throated Blue Warblers were found dead up to 22 h after release. Our results suggest application of tartar emetic is an effective but invasive method for collecting diet samples from birds. Researchers should consider alternatives, and future administration of tartar emetic should be conducted conservatively and with acknowledgment of its occasionally lethal results.