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The most important backyard in the history of bird feeding might be the one that belonged to Aelred “Al” Geis, a U.S. Fish and Wildlife Service scientist who lived in rural Maryland. In the late 1970s, on the fields of his farm, Geis did something that would transform the hobby: He conducted a rigorous study of seed and food preferences among wild birds.

Despite bird feeding already being a popular pastime, surprisingly little thought had been given to which species liked what. In fact, before Geis’s groundbreaking research, the ingredients of commercial birdseed mixes were largely chosen as a matter of custom, lore, and convenience. At best, observant birders might have picked up on which ingredients birds seemed to favor, but no one knew for sure; meanwhile, the design of most commercial feeds and mixes was largely dictated by whichever commodity grains were cheap and available. So, when Geis's paper came out in 1980, his detailed analysis quickly became the most popular paper USFWS had published to that point—and a foundation for all future bird food study.

In the mid-2000s, researcher David Horn would extend Geis’s methods to track 1.2 million feeder visits over three years across North America as part of Project Wildbird, the most comprehensive study of avian food and feeder preferences ever conducted. Horn’s findings—highlighted in this article’s accompanying chart—built on work that he was already deeply familiarly with. After all, Geis had been Horn's mentor years before.

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“I have fond memories of sitting in Dr. Geis’s mother’s living room and counting birds at the feeders outside her home, which was on the same property,” says Horn, today a biologist at Millikin University. “That property had some of the most influential studies ever conducted on wild bird feeding, and it is where I got my formal start in doing research.”

Bird Feeding: a Brief History

People have been feeding wild birds in the United States for a long time. Henry David Thoreau even mentions leaving out unripened corn for birds in his 1854 masterpiece, Walden. So why did it take another 125 years for someone to apply the scientific method to the hobby? The simple answer: Back then, people didn’t think about the food they put out for birds the way we do now. For much of U.S. history, we were an agricultural country, and the feed individuals provided was largely made up of excess grain from their own land, waste from production processes, and spoilage. 

This largely remained true through the Great Depression, when many were out of work, at home, and the hobby of bird feeding first began to take root. People put out things like leftover corn after the harvest or “scratch,” bags of waste grain they could pick up at their local grain elevator for free. It wasn’t the best quality food, but birds ate it, and folks believed they were helping their feathered visitors survive (an idea long since debunked).

During these years, as people started to pay closer to attention to the birds they fed, some of the first wild birdseed mixes for sale were formulated by observing which elements of the waste-grain smorgasbord birds devoured most readily. A one-time general store owned by brothers Simon and George Wagner that had become a supplier of caged bird feed put out a mix. So did a grain elevator partnership from the Midwest, Knauf and Tesch, that had developed feed for show pigeons. Today, Wagner’s and Kaytee (for Knauf and Tesch) are wild birdseed giants.

And yet, for decades, these commercial products still contained a lot of waste. When Geis conducted his study in the 1970s, common ingredients included numerous cheap grains that could fill out a bag of seed but that few birds actually liked. He tested 23 ingredients, including real losers like milo, wheat, hulled oats, and rice. It’s hard to say today how fast birdseed manufacturers winnowed their mixes in response to this research, but by the time Horn started Project Wildbird 24 years later, he only felt the need to test 10 ingredients. (Project Wildbird also tested different feeder types, and Horn emphasizes that the combination of seed and feeder is key to attracting many kinds of birds.)

However, from Geis’ time—and probably Thoreau’s—until now, a few things have remained consistent: Birds have always loved black oil sunflower seed. Barely anyone likes milo. Most everything in between has its place, so keep the preferences covered here in mind the next time you are buying a bag online or shopping at your local wild bird store. Pick the right mix, and you’ll be rewarded twice over: Not only will you attract the birds you hope to see, but they’ll also disappear just about everything.