Genetic component of mountain chickadees' spatial memories identified

Mountain Chickadee Credit: Vladimir Pravosudov (University of Nevada, Reno).
Researchers have discovered that Mountain Chickadees possess a genetic component that enables them to remember their spatial locations. This is the first time this has been done. These half-pound birds conceal thousands of food items each fall, and they rely on these hidden foods to survive the harsh winters in the West's mountains. Chickadees have highly developed spatial memory abilities to locate these caches. While spatial memory is genetically linked to humans and other mammals, it has not been demonstrated in birds.

These findings were published in Current Biology. This research was done in collaboration between scientists at the Cornell Lab of Ornithology and the University of Colorado Boulder, Nevada, Reno, Oklahoma, and the University of Oklahoma.

Carrie Branch, Cornell Lab of Ornithology's lead author, says that spatial memory is essential for us all to navigate our environment. "Without memory, there is no learning. An organism would need to learn every task from scratch. It is vital for these birds that they can remember where their food has been stored. It has been shown that natural selection influences their ability to recall locations.

Certain criteria must be met if natural selection (survival-of-the-fittest) is shaping chickadee memories. The trait must be varied: Some chickadees have a better record of locating their stores than others. A fitness advantage is needed: birds with better spatial memory skills are more likely to live and to produce offspring. Importantly, the genetic basis for variation must be established.

Mountain Chickadees were required to locate the feeder that would give them a seed from an array of eight feeders in order to test their spatial memory. Comparing birds who did well with the task, those who did better showed different genomes. Credit: Vladimir Pravosudov (University of Nevada, Reno).

Branch says that although environment still plays a significant role in shaping behavior, our research here suggests that genes might create brain structures. Then, experience and learning can be added to that structure."

How can you measure a chickadee’s memory? Vladimir Pravosudov, senior author, and his team from the University of Nevada Reno designed arrays of smart feeders to measure memory among wild Mountain Chickadees living in California's Sierra Nevada Mountains. Each feeder has radio frequency identification sensors. Each of the 42 birds that were tested had leg tags about the size of a grain rice. These tags emit an identification signal. Each bird was assigned to one feeder in each array. A feeder sensor reads the bird’s ID tag. If it is, a mechanism opens and the bird receives a seed. Scientists then tracked how many times it took for birds to consistently go to the right feeder.

Pravosudov stated that this is an effective way to test spatial memory and spatial learning in wild chickadees. "We have shown previously that even small differences in performance can be associated with survival."

Mountain Chickadee Credit: Vladimir Pravosudov (University of Nevada, Reno).

Scott Taylor and Georgy Semenov, co-authors at the University of Colorado Boulder sequenced Mountain Chickadee genomes to understand the relationship between genetic architecture and spatial memory. Semenov said that there were two ways to link genetic variation and spatial memory in chickadees. "In the traditional genome-wide method, we compared genetic information across individuals from those who performed well on the memory and spatial learning tasks to those who performed poorly. The same was done with a new machine-learning algorithm. There were hundreds of differences between the two methods in spatial memory. Many of the genetic variations were found in areas that are associated with learning, memory and brain development.

According to the authors, there are still many questions about spatial memory and how it influences the choice of a partner for the female.

Further exploration of Mountain chickadee research on natural selection and spatial memory links

More information: Carrie L. Branch and colleagues, The genetic basis for spatial cognitive variation among food-caching birds, Current Biology (2021). Information from Current Biology Carrie L. Branch and colleagues, The genetic basis for spatial cognitive variation in food-caching birds, (2021). DOI: 10.1016/j.cub.2021.10.036