Want to protect birds? Ban pesticides.

Want to protect birds? Ban pesticides.

After DDTs were tanking the bald eagle population, the US banned them in 1972, and their numbers slowly rebounded in the wild. But modern pesticides are still widely used in farming in the US and around the world, and birds continue to suffer their deadly effects. Here’s what you need to know about pesticides—or neonicotinoids—that harm our feathered friends, and what you can do to fight for their future.

March 16 2023 Jillian Anthony

The Bobolinks were disappearing. In 2013 the scientific journal ​​PLOS ONE published a peer-reviewed study showing how insecticides and the decline of grasslands had a deadly effect on birds in Europe and North America, including the once-common Bobolink in New England. 

“They are one of these species that goes down to the large grasslands in Central and South America, where pesticide use is really strong,” says Scott McWilliams, an ornithologist and professor in the Department of Natural Resources Science at the University of Rhode Island. “You can point to birds as being the sentinels in the environment. There’s some disturbing negative effects of pesticides; it screws up [birds’] orientations. [Pesticides] get in the way of [birds] using their natural navigation systems to make their way, and that’s a death knell for a lot of migratory birds.”

The type of pesticides that most affect birds are called neonicotinoids, or neonics for short. Neonics were first introduced to the US in 1994, according to the American Bird Conservancy (ABC), and can include insect sprays, seed treatments, and even veterinary ointments for flea control. Neonics are not only present in birds’ food supply; they’re also present in groundwater, affecting fish and amphibian populations, and even in the food we eat. The ABC’s 2013 report on neonics’ effect on our natural ecosystems showed that “neonicotinoids are lethal to birds and to the aquatic systems on which they depend,” stating that “a single corn kernel coated with a neonicotinoid” could kill a songbird.

The reason neonics are so harmful to birds specifically is because they are soluble in lipids, or fats, the mainstay of migratory birds’ diets. During migration periods, birds can double their mass, storing fat to use as fuel for their journeys. Over time, pesticides in the birds’ food supply can biomagnify, impairing them. Other animals face these same challenges, including reptiles, fish, and bees, whose floral food sources have also been proven to be laced with pesticides. (Cornell’s 2017 study found that ​​60 percent of the pesticides found were within farmlands that were not sprayed during the recent season, meaning pesticides travel, and persistently linger through seasonal changes.)

[Biomagnification] means that at each step of the [food] chain, the actual concentrations [of pesticides] go up,” McWilliams says. “[Larger predators tend to eat] the things at the bottom of the food chain, [or] the herbivores. So there’s a certain concentration [of pesticides] in one [animal or plant], but if you eat 100 in your lifetime… It’s the same reason why a lot of the fishermen don’t eat the larger predatory fish, because they know that there’s a biomagnification. And if you eat an older fish, it’s more likely to have magnified any kind of toxins in the environment.”

Scott McWilliams

The United States grappled with its own pesticide use in the early 1970s, when the widespread use of an agricultural pesticide called dichlorodiphenyltrichloroethane, or DDT, threatened the nation’s symbol of livelihood: the Bald Eagle. Bald Eagle populations began dropping as a result of biomagnification of DDT in the environment, thinning the eagles’ eggshells and making it impossible for them, and other large birds of prey such as peregrine falcons, to successfully reproduce. 

“As soon as DDT stopped being used—it’s taken decades—but the levels in the environment went down, the levels in the eagles and the peregrines went down, and they were able to successfully produce eggs that they could sit on and incubate and hatch,” McWilliams says.

Even though some major pesticides such as DDT have been outlawed in the United States, other countries still use them, so migratory birds still ingest them. 

“It doesn’t help that Bolivia and Colombia haven’t outlawed those things, and are still using large quantities, because the birds will encounter them at other times in their annual cycle,” says McWilliams. “And we don’t have the regulation here in the US for these commonly used pesticides. And so we’re finding them to be common in backyards, and even in the food sources we eat.”

While there are still many unknowns to how current pesticide use affects both humans and animals in the long term, there are ways for you to help curb their long-reaching effects today. Kristen DeMoranville, who has a PhD in bird ecology and physiology from URI, suggests reading your food labels to check for non-natural ingredients, as well as buying your food from organic, local growers whenever possible. (And buying organic bird seed for your feeders.)

“If you buy your food locally, and you know where it’s coming from, and the people who are growing it can tell you that they’re not using [pesticides],” McWilliams says, “then you are promoting the kinds of food-growing and food consumption that helps the cause.”

Plus, you can get involved with local organizations working to help pass legislation for the regulation of pesticides. 

“Stopping the use of pesticides, and being more responsible in our use, is really what’s going to help these bird populations and minimize their consumption of pesticides,” DeMoranville says, “and our consumption as well.”