Pesticides are like a pestilence to such insects as bees and butterflies. Now hummingbirds can join that sad grouping of creatures that are poisoned with toxic chemicals that literally harm and in some cases kill them.
These are the same pesticides that are named over and over again in countries all around the world. These pesticides account for much of the global decline of insect pollinators. They also present significant risks to hummingbirds, those amazing little jewel-colored birds whose wings beat more than 50 times per second. These unique birds are known for their ability to hover in flight as they drink nectar.
Canadian scientists at University of Toronto have researched hummingbirds and found they display unique reactions when exposed to toxic systemic neonicotinoid insecticide pesticides, even briefly. Their high-powered metabolism is disrupted.
This unrelated 1:17-minute video by Wiley shows Rufous hummingbirds that are disappearing from North America:
The experiment began when scientists trapped 23 wild ruby-throated hummingbirds and housed them in an animal care facility. They were split into several groups. One group acted as a control group and was not exposed to pesticide. The other groups were exposed to the neonicotinoid imidacloprid, and assigned low, medium, or high exposure at 1 part per million (ppm), 2 ppm and 2.5 ppm respectively. Scientists determined the amounts based on probable nectar contamination in nature. The pesticide was added to the sugar solution the birds received over a three-day period.
After only two hours of exposure to the pesticides, the metabolism of affected hummingbirds dropped significantly. In contrast, the control group experienced increased energy expenditure of 1%-7%. The mildest exposed group showed a 6% average decline, the medium group a 10% decline and the highest exposure group a 25% reduced energy expenditure.
Ken Welch, PhD, author of the study, said they don’t know why it goes down. Maybe the chemical disrupts the metabolic processes. Chemical exposure could also be making them feel sick. Either way, they definitely show the reduced metabolic rate during the first few hours after they ingest it. There was no apparent impact on feeding or flying behavior, and although researchers didn’t observe any other signs of neurotoxicity, clearly there are wide-ranging effects for hummingbirds exposed to these insecticides. As Dr. Welch said, they only carried out observations for the first few hours after exposure. There could be a long-term impact on the central nervous system. The press release is here.
Neonicotinoids act on the insect’s nicotinic acetylcholine receptor (nAChR). Bindings to that site essentially paralyze a target insect by impeding movement and breathing. Although the pesticide industry has claimed for a long time that this is only harmful for invertebrates, Dr. Welch notes that we can assume that those potential risks also exist for hummingbirds through long-term exposure. He says more research is required because we just don’t know.
Hummingbirds rely on razor thin margins of error and a sophisticated high-speed navigation system. Given their high energy demands, neonicotinoids may significantly damage the hummingbird’s fitness ability in the wild. According to Dr. Welch, hummingbirds may skip their normal foraging behavior due to a dip in their metabolic rate and this could put them into an energy bottleneck. They could also go into an energetic crisis if they are already low on energy and are then exposed to this pesticide.
These recent discoveries and findings highlight a regulatory approach that fails to embrace precaution from the outset. The dangers that neonicotinoids pose to hummingbirds are now being revealed decades after the chemicals were first permitted to be used in the environment, and not by regulatory agencies but rather by independent scientists.
Overwhelming data on the dangers and threats of neonicotinoids to ecosystems worldwide has already been established. There is an extensive list of animals found to be adversely affected by neonicotinoids, and it ranges from humans and other mammals to insect pollinators, songbirds, amphibians, and other aquatic species.
Regulators in Canada and the European Union deserve some credit for following the science. They tracked impacts after approval and eventually banned most neonicotinoid use. The same cannot be said about the US Environmental Protection Agency (EPA). Proposed label changes will do little to stop or reverse the damage these chemicals do to the natural world.
Moving toward safer, organic practices will protect pollinators and the entire circle of life on which our human society depends. Supply and demand rule our world. If enough of us consciously embrace organic crops, eventually demand for foods grown with poisonous chemicals will fade away. Neonicotinoid insecticide elimination is the solution for the future of humanity and other species that so enrich our lives.
Learn more about the dangers of pesticides on wildlife at Beyond Pesticides. And think about how you can support your local organic farmers and beekeepers.