Researchers work to uncover the secrets of Mountain Chickadees


Her voice hushed, barely a whisper, a female Mountain Chickadee is calling inside the cavity in a weathered gray snag. From a nearby pine, her mate sings to her. He, too, is scarcely audible.

The female pops into view at the entrance to the cavity. Her dark eyes glint in the black stripe across her face. The two little birds call back and forth. Their hushed voices suggest an intimate conversation. I feel like I’m eavesdropping on a private exchange. I’m overhearing secrets being shared.

Secrets I would love to understand. 

She must like what the male is saying to her. She lifts out of the cavity and bounces into the tree where he is singing. 

This pair of Mountain Chickadees are nesting in the pine forest of the Sierra Nevada not far from Truckee, California. Their nest is in a stump at a research site where biologists have uncovered startling secrets about the minds of these birds. It’s a clever study, using innovative, high-tech, programable “smart feeders” that enable the scientists to test memory and learning. 

The research on this species of mountainous regions of western North America is part of a sea change in the interest in and study of the avian mind. These unlikely chickadees may possess mental abilities that rival the skills of some of the more celebrated intellectual stars of the bird world. 

The data might even help me understand the secrets that pass between these two courting chickadees.

The snowy peaks of the Sierra Nevada mountain range in eastern California stretch out from the Sagehen Experimental Forest, the site of the chickadee research. The 9,000-acre forest is managed in a partnership between the University of California and the U.S. Forest Service. Photo by Vladimir Pravosudov

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Chickadees are among the most beloved birds in North America. They are favored wild companions in our daily lives, regular visitors to our feeders and our gardens. We love the jauntiness of their flight, the lilt and lift of their song. They possess an irresistible cheerfulness. 

Yet we have almost certainly underestimated chickadees, particularly when it comes to their intelligence. Perhaps it’s their small size. Perhaps it’s that they’re so cute and unassuming. Perhaps it’s that we have trouble thinking that minds and feathers go together. 

In any event, chickadees seem an unlikely place to look for high intelligence. But in Vladimir Pravosudov, they have found an enthusiastic and clever champion. The Mountain Chickadees I am watching are on his study site. When I hear a pickup truck clattering up the forest service road, I duck out of my camouflage by the nest and walk over to meet him.

A foundation professor of biology at the University of Nevada, Reno, Pravosudov is among the leading researchers who are transforming how we see chickadees and birds generally. He will make the case that chickadees deserve a place in any conversation about the most intelligent birds.

“Chickadees are the best birds,” he tells me with an engaging sincerity. “Never mind that they are only black and white. Absolutely all chickadees are incredibly smart in terms of learning and memory. They hold more answers to cognition and adaptations to harsh environments than many more colorful birds.”

Pravosudov is wearing an Arc’teryx hoodie and wrap-around sunglasses that create a dark stripe over his eyes. I smile to myself because they give him a striking resemblance to his beloved Mountain Chickadees.

“Don’t get me started on the wonders of chickadees,” he laughs. His energy is infectious, and his passion for these birds is unmistakable. “I could be telling stories for weeks.” 

But that’s exactly what I want him to do — tell chickadee stories. 

I’ve come to the Sagehen Experimental Forest in the Sierra Nevada to learn about his research on Mountain Chickadees — and even more, to take an eye-opening journey with him into the chickadee mind. The sun is warm and the air heavy with a pine-forest perfume. We sit on the thick layers of fallen pine needles. 

A little context helps to understand the significance of Pravosudov’s studies of Mountain Chickadees. Before the 1990s, avian intelligence was considered an oxymoron. The term “bird brain” was also a contradiction in terms. It was a term of opprobrium, an insult. Birds’ brains are too small to be capable of thought, the thinking went, too different from the human brain to support anything like real thinking.

Vladimir Pravosudov of the University of Nevada, Reno, stands with his specially designed “smart feeder” that he uses to study Mountain Chickadees. Photo by Charles Bergman
Vladimir Pravosudov of the University of Nevada, Reno, stands with his specially designed “smart feeder” that he uses to study Mountain Chickadees. Photo by Charles Bergman

Birds were viewed as mindless creatures of instinct.

Then groundbreaking studies of parrots and corvids (crows, jays, and nutcrackers) began to change the landscape of animal thought. Now, the field of “animal cognition” has exploded. In their more relaxed moments, biologists might use terms like “intelligence” and “smart.” It’s almost unavoidable. Nevertheless, in formal settings, they prefer the term “cognition.” It is less fraught with human associations and baggage. Cognition can be defined as the means by which an animal acquires, possesses, stores, and uses information.

Pravosudov’s career has spanned the birth and growing maturation of the burgeoning field of bird cognition. As a master’s student in Leningrad, Russia, his research interest was on food caching, which is one of the key behaviors that provide insight into the minds of birds. 

Food caching is a way for industrious and energetic birds to store seeds in the summer for consumption in the winter. Mountain Chickadees, for example, tuck seeds wherever they can find a good spot, in crevasses of bark or even between needles at the ends of branches. They turn their forest into a kind of food bank, which they can “cash out,” as it were, in winter when they need food to survive. 

Most chickadees are food cachers. Only the Mexican and Chestnut-backed Chickadees do not cache seeds. According to Pravosudov, Mountain Chickadees can cache tens of thousands of seeds in a year. 

Finding those seeds again in the winter, when the landscape looks so different from its summer appearance, requires an astute memory and the ability to orient oneself in space.

“We call that spatial cognition,” Pravosudov says. 

His early interest in food caching did not involve cognition, however. He studied Willow and Siberian Tits. They are “parids” — a family of birds that includes Eurasian tits and North American chickadees and titmice. “I studied caching as an adaptation to life in the north,” he explains.

After coming to the United States, Pravosudov began studying food caching and cognition in chickadees. Through lab research, he found that Black-capped Chickadees in harsher environments in Alaska cached more food and “showed better spatial learning and memory abilities” than those living through milder winters in Colorado and Kansas.

When he came to the University of Nevada, Reno, he soon realized that the Mountain Chickadees of the Sierra Nevada would enable him to take his studies from the lab to the wild. And to do that, he and a colleague in Oklahoma invented an ingenious “smart feeder” to learn just how smart the birds are. “They are abundant, learn quickly, and let us study them.”

I ask him if chickadees may be smarter than humans in some ways. 

Pravosudov flashes a Puckish smile. “No doubt,” he answers. “Chickadees have way better memories than you do. Or than I do. Way better.”

I laugh because half the time I cannot find my wallet or my cellphone.

The chickadees are calling to each other again at the nest. As I get back under the camouflage, Pravosudov offers to show me the fabled feeder tomorrow. “It will help you understand how we know the chickadees are so smart.”

A Mountain Chickadee perches on the "smart feeder" to find a seed. The birds in the study wear transponders on their legs that communicate with an electronic system inside the feeder that identifies each chickadee. Vladimir Pravosudov
A Mountain Chickadee perches on the “smart feeder” to find a seed. The birds in the study wear transponders on their legs that communicate with an electronic system inside the feeder that identifies each chickadee. Vladimir Pravosudov

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If this were a sci-fi movie, the feeding station might be a portal to another dimension. It’s suspended from cables high in the pine trees. Pravosudov lowers it for a closer look. It’s a large aluminum frame, about 5 feet by 5 feet. On each side of the square frame are two gray feeders for a total of eight in all. He calls it a “spatial array.”

Pravosudov conceived and designed the station and then had it custom built. It’s wired, computer-programmed, and stunningly hi-tech — a “smart feeder.” Each of the feeders on the station has a small door that dispenses seeds. By each door is a perch with an embedded antenna that connects to a circuit board equipped with RFID (radio-frequency ID) ability. 

Chickadees are trapped with mist nets and fitted with PIT-tags on their legs (passive integrated transponders). 

This daunting technical language describes an electronic system that communicates with the tags on each chickadee’s leg. Every visit to a perch by every chickadee is noted, and individual chickadees are identified.

With the patience and clarity of a practiced teacher, Pravosudov explains the tests he gives the chickadees to measure their spatial memory and learning.

The tests are conducted in phases. First is an “open” phase. The doors of all the feeders are open, and chickadees can visit any of the eight feeders to retrieve seeds. The point is to habituate the chickadees to the feeders and the station.

The second phase is called “all.” The doors are closed, but every door is programmed to open to every chickadee when it lands on the perches. The point of this phase is to habituate the chickadees to the opening and closing of the feeder doors.

The third phase is called “target.” In this phase, each door is programmed to open only to those chickadees whose PIT-tag identifications match a list for that specific RFID circuit board. Each feeder has a different list.

In this phase, the chickadees are searching for the feeder with the door that opens for them. The system can track how many visits it takes for each chickadee to figure out which door is its. 

Once the chickadees figure out which perch is “theirs,” they make no more mistakes. 

On this test of memory and learning, some chickadees do better than others. Since 2014, Pravosudov and his grad students have tested 100 to more than 200 individuals per year. The chickadees at higher elevations, where the weather is harsher, do consistently better than those at lower elevations.

After many years of research, Pravosudov and seven colleagues published their findings in November 2021 in the journal Current Biology. The study is the first to find that genetics underly the amazing spatial memories of Mountain Chickadees.

Co-authors Georgy Semenov and Scott Taylor at the University of Colorado Boulder sequenced the genomes of birds that performed the best and worst on a spatial cognitive task.

“We used two methods to link genetic variation with spatial memory in chickadees,” Semenov explains. “In the traditional genome-wide approach, we compared genetic data across individuals, from those that performed well on the spatial learning and memory task to those that performed poorly. We did the same comparison with a new machine learning algorithm. Both methods showed hundreds of differences associated with spatial memory. Many of the variations in the genomes turned up in areas known to be associated with learning, memory, and neuron development in the brain.”

As Pravosudov explains, “Every year, 50 percent of the chickadees die, usually in winter. The birds do not migrate. At the high, harsh elevations, only the smartest survive.”

For them, intelligence is a survival skill, and harsh winters illustrate the way natural selection works on animal minds as well as bodies.

Pravosudov grows animated with delight as he tells me that he has also done tests that show the chickadees can “predict the future.” If he moves the assigned perch for a chickadee around the station, the chickadees can discern the pattern and anticipate the correct feeder.

He did experiments in his lab with Black-capped Chickadees. If they know they are being watched by a bird that might steal their food, they will hide it. If watched by a junco, they will not try to hide it. Juncos do not cache so are not a threat.

“I’ve studied parids my whole career,” he says. “Chickadees are marvels. They are among the smartest birds. They’re not far from corvids. They cache more food than nutcrackers. They can hide caches and know who will and will not steal their food.”

He is both a clear-headed scientist and a passionate, convincing advocate for these humble birds.

Mountain Chickadee nestlings huddle in a nest box. Photo by Charles Bergman
Mountain Chickadee nestlings huddle in one of 358 nest boxes within the Sierra Nevada study site. The nestlings are surrounded by sheep’s wool, which is an experimental nest lining. Mountain Chickadees typically gather animal hair to top and line their nest cups, so this nest is similar to a natural chickadee nest. Photo by Charles Bergman

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For female chickadees, it turns out, bigger is better. 

Ben Sonnenberg is a grad student in Pravosudov’s lab studying nesting behaviors of Mountain Chickadees and one of the co-authors of the Current Biology paper. In addition to being a dedicated biologist, he’s an avid and highly skilled birder. I have joined him and Pravosudov for the morning as he monitors nesting chickadees — 358 nest boxes on the study site.

We amble through the open understory of the pine forest. Sonnenberg identifies several birds by their calls — Hermit Warbler, Western Tanager, Cassin’s Vireo. At the nest boxes, he reaches in to make sure he’s counting all the eggs or hatchlings. 

“The female does all the nest building and incubating,” he tells me. 

It turns out that it is not only natural selection that chooses the smartest chickadees. So do the female chickadees. They choose the smartest males for their partners. 

Pravosudov explains, “Our data suggest that females can tell which male is better or worse at spatial cognition — and we showed that when they mate with a ‘better’ male, they lay larger clutches.”

In both people and birds, a particular region of the brain is associated with memory and spatial learning — the hippocampus. With Black-capped Chickadees, Pravosudov showed that greater spatial cognition is also associated with a larger hippocampus. 

Females, therefore, seem to prefer males with a larger hippocampus. “How do the females know which male has the bigger hippocampus?” I ask.

“The females maybe can tell by proxy characteristics,” Sonnenberg says.

Pravosudov adds that Carrie Branch, a postdoctoral fellow at the Cornell Lab of Ornithology and the lead author of the recent chickadee genetics paper, is studying the question. “She has shown that the males’ songs have significant differences, and, we think, their songs reveal different cognitive abilities.”

So, females may be using song structure to discriminate among males’ cognitive abilities.

A male Mountain Chickadee (right) presents an insect to his mate outside their nest cavity in a tree at the study site. Photo by Charles Bergman
A male Mountain Chickadee (right) presents an insect to his mate outside their nest cavity in a tree at the study site. While accepting the bug, the female flutters her wings in a pair-bonding behavior. Pairs remain together throughout a breeding season and may mate for life. Photo by Charles Bergman

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After lunch, I return to the pair of chickadees in the natural nest cavity that I had been watching. I am hoping to see the male and female interact. 

I spend many hours at this nest, lots of alone time with the chickadees. I find myself thinking about something Sonnenberg had said. 

I had asked him what he liked best about Mountain Chickadees.

“I am amazed that such a small and relatively well-known bird can teach us such vast secrets of cognition,” he said.

The female Mountain Chickadee begins calling again from inside the tree. She pops up into the entrance. Under the patina of gray on the surface, the wood at the hole is a vibrant orange. She seems perched in a flame.

The male sings back to her. They chirp and gargle back and forth as they had done on my first day with them. This time, however, the female does not fly to him. Instead, she spreads her wings, and they begin to shake and vibrate. This must excite the male. He flies to her at the nest hole. 

He carries an insect in his beak. She turns to face him, wings still shaking. Beak to beak, she takes the insect. Is the secret of this quivering conversation that the male is putting his intelligence on display in his song? A conversation of cognitive fitness? Has he proven that he is smart enough for her? Perhaps he flew in to seal the deal with a buggy kiss. 

For more information on research about food caching by Mountain Chickadees, visit chickadeecognition.com. Read the Current Biology paper mentioned in this article (and to view videos about the study) here.

This article was first published in the March/April 2022 issue of BirdWatching Magazine.


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