If you’re hungry in the mountains and can’t remember where that little place is that has the special plate with the thing overlooking that view, follow a chickadee.
New research from the University of Colorado and colleagues has tightened a claw around the sets of genes that make mountain chickadees some of the most remarkable return-navigators in nature. They remember where the seeds are.
But don’t get too attached to that particular group of winged map nerds. It may be the more forgetful chickadees we want to follow in the future. As climate change creates more storms that wipe out, dry up or inundate key feeding spots, it may be the most forgetful and therefore adaptable chickadees who are the most successful foragers in Colorado’s future.
“There seems to be a behavioral trade-off, where individuals that are good at this spatial memory task are less flexible in their behavior, which is really interesting to think about,” said Scott Taylor, director of CU Boulder’s mountain research station and an associate professor of ecology and evolutionary biology. “If the environment is more variable, flexibility might be a better survival strategy than just having a really good memory. And so we’re not just measuring the best of the best chickadees, in a way because they’re the best at this task that sometimes is really good for survival, but other times might not be.”
The CU collaboration with University of Nevada researchers was published in April in “Current Biology.” The paper identifies dozens of genes linked to the small birds’ spatial memory — their skill in remembering where objects were.
In the natural world, the genes allow the highest-performing chickadees to remember exactly where they stashed food for the winter in a wide range, whether inside a tree hollow, under leaves or inside a pine cone, according to CU.
Nevada researchers established the brain test in the Sierra Nevada by spreading out feeders with automated gates. The gates would only open when a precisely tagged bird would land on their assigned perch. Over time, the tags allowed researchers to record how frequently each bird went to the right or wrong perch.
Blood samples from the tagged birds then allowed researchers to match DNA traits with the birds who performed exceptionally well or those who stayed hungry longer with a wrong choice.
Taylor and study lead author Georgy Semenov replicated the feeder array at CU’s mountain research station, a few miles north of Nederland. The Rocky Mountain chickadees have evolved separately from those in the Sierra Nevadas, and part of the experiment was to see if the same traits showed up in separate populations.
Chickadees are a focus for a number of reasons, Taylor said, in part because they are ubiquitous in the mountains and foothills. But also, he said, even while weighing in at less than half an ounce, “They’re relatable, they’re familiar and they’re also just pretty badass birds in terms of their ability to remember thousands, tens of thousands of locations, and then survive over the winter. If you put me at 10,000 feet, I would not survive.”
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It’s humbling to keep studying a bird with a brain the size of a pea, the researchers said.
“Even the chickadees that didn’t perform as well on this test have much better spatial memory than humans and many other organisms,” Taylor said.
When researchers are able to tag much wider populations of birds, they can see the natural selection principles play out.
“If you were to measure all the individuals in a population that are juveniles before their first winter, and then you measure everyone the next year, the ones that have died are the ones that perform the worst on that memory task,” Taylor said.
Perhaps in the name of science, or perhaps out of revenge, the researchers then took the study to another level by yanking the familiar feeders and assigning the tagged birds a new seed portal somewhere else.
“They found chickadees that performed better in the initial test tended to struggle with remembering the new feeder. They seemed to have a harder time abandoning their initial memories and creating new ones,” a CU summary said of the second phase.
Which leads to speculation about survival in the wake of climate change. In an environment with more and more wild weather and habitat variables each year, it may be the laid-back, forgetful, eat-what’s-in-front-of-you chickadees that do best, the researchers postulated. They will rely less on stashes they can recall, and more on bonus food they flit across on a random flight.
“If you have the ability to form new and different memories faster, maybe that’s a better way to survive,” Taylor said. “An important piece of it is that there’s more than one way to survive a winter as a chickadee.”