February 23, 2021 | The same pesticides implicated in the worldwide decline of insect pollinators also present significant risks to their avian counterparts, hummingbirds. Well-known for their nectar-fueled hovering flight powered by wings beating over 50 times per second, hummingbirds display unique reactions to toxic pesticides. Researchers at the University of Toronto published in Scientific Reports findings that a hummingbird’s exposure to systemic neonicotinoid insecticides for even a short period of time can disrupt the high-powered metabolism of this important and charismatic animal. Scientists began their experiment by trapping 23 wild ruby-throated hummingbirds and housing them in an animal care facility. One group of birds acted as a control and received no pesticide exposure, while the rest were assigned either low, middle, or high exposure (1 part per million [ppm], 2ppm, and 2.5ppm, respectively) to the neonicotinoid imidacloprid. Scientists determined these amounts based upon probable nectar contamination in the real world. The pesticide was incorporated into the sugar solution provided to the birds over the course of three days. Within two hours of exposure to the pesticides, hummingbird metabolism dropped significantly. While the control group increased energy expenditure between 1% to 7%, the low exposed group displayed a 6% average decline, the medium a 10% decline, and the high exposure group showed 25% reduced energy expenditure. [English, Simon et al. Neonicotinoid pesticides exert metabolic effects on avian pollinators. Scientific Reports. 11:2914, 2021.]
