In a recent study published in Current Biology, researchers from the University of Colorado Boulder and the University of Nevada, Reno have identified nearly a hundred genes associated with the impressive spatial memory of mountain chickadees. These tiny birds can recall the locations of tens of thousands of food caches they have hidden across the mountains, allowing them to survive harsh winters. The study also suggests a potential trade-off between having strong long-term memory and the ability to quickly form new memories. Understanding this genetic basis of spatial memory could help biologists understand how this trait evolves in animals, including humans.
To test the spatial memory of mountain chickadees, researchers hung multiple feeder arrays in the Sierra Nevada mountains, each with eight bird feeders. Each feeder had a gate that would only open to certain birds, requiring the chickadees to remember the locations that were accessible to them. Through this clever test, the researchers were able to assess the birds’ spatial memory by counting how many times they landed on the wrong feeders before finding the correct one. The birds with better spatial memory had lower error rates, indicating their ability to remember the locations accurately.
The team also sequenced the entire genome of 162 tagged chickadees, creating a comprehensive dataset to evaluate the genetic basis of cognitive ability in these birds. By comparing the genetic variants of the birds with their performance on the feeder test, the researchers identified 97 genes associated with spatial learning and memory in chickadees. Many of these genetic variants are linked to neuron formation in the hippocampus, the part of the brain responsible for learning and memory. Understanding the genetic foundation of spatial memory could shed light on how this trait evolves and varies among different bird species.
Interestingly, the study found that there may be a trade-off between exceptional spatial memory and the ability to adapt to changes in the environment. Chickadees with strong long-term memory struggled when new feeders were introduced, as they seemed to have difficulty abandoning their initial memories and forming new ones. In a variable environment, having good long-term memory may pose challenges, as birds may struggle to adapt to unexpected changes, like snowstorms burying their caches. This suggests that birds with the ability to quickly form new memories may have an advantage in rapidly changing climates.
As the climate continues to shift rapidly, the selective pressures that have shaped the spatial memory of chickadees for thousands of years may change significantly. The researchers at the University of Colorado Boulder plan to continue their experiments with feeder arrays to study how different groups of mountain chickadees, as well as black-capped chickadees, adapt to changing environments in the Rocky Mountains. By studying these familiar birds, researchers hope to gain insights into how animals may respond to climate change and other environmental challenges.
