External feather rinsates and homogenized whole-carcass tissue matrix from California Anna’s Hummingbirds (Calypte anna) and Black-chinned Hummingbirds (Archilochus alexandri) were analyzed for the presence of nine insecticides commonly used in urban settings. Using a novel liquid chromatography-high resolution mass spectrometry (LC-HRMS) analytical method, samples were quantitatively screened for the following key insecticides: sulfoxaflor (sulfoxamine class), carbaryl (carbamate class) and the following neonicotinoids: dinotefuran, nitenpyram, thiamethoxam, acetamiprid, thiacloprid, clothianidin and imidacloprid. This analytical method was also used to qualitatively screen for the presence of approximately 150 other pesticides, drugs, and natural products. The small body size of hummingbirds limits traditional sampling methods for tissues or whole blood to evaluate for pesticide exposure. Thus, utilization of this analytical method may allow for future studies of species with low body mass (<5 grams), provide insight into avian pesticide exposure, and ultimately lead to improved conservation of hummingbirds and other avian pollinators.
Results/Conclusions
Feather rinsate and homogenized carcass samples from both hummingbird species (n=64 individual hummingbirds) had detectable concentrations of carbamate, sulfoxamine, and neonicotinoid classes of insecticides. Imidacloprid, acetamiprid and thiacloprid were detected at trace but non-quantifiable concentrations in homogenized carcass samples while carbaryl, malathion, dinotefuran, imidacloprid, thiamethoxam, and acetamiprid were detected at trace but non-quantifiable concentrations in feather rinsates on Anna’s and Black-chinned Hummingbirds found in California. One Anna’s Hummingbird carcass contained quantifiable levels of imidacloprid (3.2ppb) and two Black-chinned Hummingbird carcasses contained quantifiable levels of acetamiprid (3.1-3.4ppb). Combined results of the rinsate and homogenized samples showed that 44 individuals (68.75%) were positive for between one and four target compounds. Since hummingbirds are a highly mobile group of species with varying migration strategies, we cannot currently speculate where or how this exposure is occurring. Overall, the results from this study show that hummingbirds found in California are exposed to a suite of insecticides and that feather rinsates and carcass homogenates are matrices that can be used for assessing pesticide exposure in small bird species.