New grant to study life-and-death trait of chickadees

Mountain chickadee perching on a branch

Spatial cognition—how space is perceived and remembered—is an incredibly important trait that can determine life or death for chickadees, yet not much is known about it or how it developed. A new grant awarded to the University of Colorado Boulder and the University of Nevada Reno, though, aims to provide some insight.

This $2.7 million National Science Foundation grant will allow researchers from both institutions to build off existing research to examine the genetic underpinnings of spatial cognition—and the role natural selection may play on the trait—in mountain chickadees in both the Sierra Nevada and the Rocky Mountains.

Beyond just chickadees, though, this new grant will also allow the researchers to study natural selection on a complex behavioral trait, an incredibly difficult task that could potentially expand the ways natural selection is studied broadly, while also shedding light on how it relates to a changing climate.

“Even documenting natural selection on relatively simple traits like coat color in the wild is difficult, and behaviors are harder to pin down for a lot of reasons,” said Scott Taylor, an assistant professor at CU Boulder and the new director of the Mountain Research Station, who is one of the lead investigators on the grant.

“Especially things like spatial cognition, for a long time, people thought that it’s all environmental or its all learned and there’s no genetic basis. But our preliminary data show that there is likely some genetic basis for the trait, and this grant will explore our preliminary findings in more depth.”

Chickadees do not migrate like some other bird species, which means that they have to survive the winter. To do that, chickadees, which have long been known for their spatial memory, rely on food reserves or caches that they’ve hidden throughout the season as a consistent source of food.

“The reason they (chickadees) have such great memory abilities is that they use spatial learning and memory to find these caches. If they fail to find them during critical times of need in the winter, they are likely to die, so having good spatial cognition is critical for their survival,” said Vladimir Pravosudov, a professor at the University of Nevada Reno and the other lead investigator.

Pravosudov used that behavior to his advantage to study their spatial cognition. He created a spatial array, or a group of sensors designed to test spatial learning in memory in wild chickadees in their natural environment. Each array consists of eight “smart” feeders equipped with Radio Frequency Identification (RFID) technology allowing him and his lab to control which bird can get food at each feeder.

All chickadees were also banded with unique passive integrated transponder tags, which are then detected by the RFID board in each smart feeder when any bird lands on the feeder perch with the embedded RFID antenna. That board can then grant access to the food within the feeder, making it possible to assign each bird to a single feeder within the array.
The researchers then measured spatial learning and memory by looking at how many errors the individual birds make as they become familiar with the spatial location of their rewarding feeder.

While Pravosudov’s lab was collecting these data, Taylor, who studies the genetic underpinning of speciation within chickadee populations, was invited to give a talk at the University of Nevada Reno. What initially began as a simple conversation of the genetics underlying spatial cognition between the two labs became a “well, maybe,” and they decided to give it a try through a pilot study looking at the highest and lowest performing individuals.

“It’s usually hard to measure traits in wild populations and relate those to natural selection. … This research expands the kinds of ways we can explore how natural selection operates in nature and then, ultimately, shapes the variation that we’re fascinated by.”

Scott Taylor, Assistant professor at cu boulder, lead researcher

Their initial findings, which are in a forthcoming paper, suggest that genetics is at play. This fits with Pravosudov’s recent findings that provide strong evidence that this complex behavioral trait is acted upon by natural selection. In other words, chickadees with better spatial cognition are more likely to survive their first winter of life and thus reproduce come spring.

“This was a critical finding, as it has long been hypothesized that differences in cognition between populations and species evolve via natural selection, but the only previous evidence available was indirect, based on comparative studies,” said Pravosudov.
And Taylor agrees:

“It’s usually hard to measure traits in wild populations and relate those to natural selection,” he said. “This research expands the kinds of ways we can explore how natural selection operates in nature and then, ultimately, shapes the variation that we’re fascinated by.”
This National Science Foundation grant, which was recently funded, allows both labs to expand the study to even more chickadees both in the Sierra Nevada mountains—where the initial research was conducted—and at the Mountain Research Station, where more smart feeders will be installed.

While Taylor’s lab begins a genomic analysis of samples previously collected over seven years by Pravosudov’s lab to see if they can pinpoint the most important regions of the genome related to variation in spatial cognition in chickadees, Pravosudov’s lab will continue gathering results with the smart feeder arrays.

The new data, beyond just allowing the researchers to understand natural selection’s role broadly speaking, will also allow the researchers to look at the impacts of yearly variation in winter, with some years getting more snow than others.

Considering consistent trends in climate warming, the researchers think this study might provide insight into how such warming affects cognition and genetic variation within chickadees.

“This study provides a rather unique opportunity to investigate how variation in winter climate, which is likely the main driver of natural selection on spatial cognition in food-caching birds, can affect the strength of selection, cognitive abilities, as well as genetic variation underlying these abilities across different montane environments over multiple years,” said Pravosudov.

Beyond just collecting and analyzing the data, Pravosudov and Taylor also plan on conducting public outreach related to the research by establishing the feeders in easily visible areas and creating materials aimed at K–12 audiences talking about the trait and why it’s important. The grant will also allow them to bring on additional research opportunities for undergraduates, graduate students and postdocs.

“I think this grant is going to help our research expand in a new and exciting direction,” said Taylor.

Republished with permission from the Colorado Arts and Sciences Magazine.

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