Like humans, chickadees depend on the hippocampus in their brains to create episodic memories. Compared to birds of comparable size that aren’t known to cache food, chickadees have a much larger hippocampus. Aronov and his colleagues sought to learn more about how black-capped chickadees’ neural activity reflects the formation and retrieval of episodic memories.
It’s impossible to say for sure on a trial-by-trial basis, but “statistically, we have to invoke memory in order to explain their behavior,” he said. What about the times the chickadees checked empty caches? Were they making a memory error, or were they purposefully checking an empty siteeven knowing it was emptyfor their own mysterious reasons?
Aronov claims that all it takes to establish a fresh, enduring, and site-specific pattern is a single instant of caching. The implications of that are amazing. Chickadees have the ability to store thousands of moments in thousands of locations, which they can access whenever they need more food.
Its still unclear how the retrieval process works. We know from Aronov’s research that when chickadees see one of their caches, their brain activity patterns can be reactivated at that specific location (even if they haven’t yet seen what’s inside). However, suppose a chickadee has hidden a seed in a specific tree’s bark. Not sure if it can remember its cache site by sight, or if it can just go about its business on the other side of the forest, decide it’s hungry for a seed, and then visualize its nearest cache location without physically being there, is what scientists are trying to figure out.
According to Aronov, birds frequently “check” caching sites both before and after storing food there in addition to caching and retrieving food from them. Naturally, a bird can see whether there is food inside as soon as it opens one of the flaps. Therefore, it is impossible to determine whether changes in brain activity when a bird checks a site are caused by memory or just vision when measuring the brain activity of the bird after it has lifted a flap. Therefore, before the bird had a chance to open a flap and reveal what was inside, the researchers focused on the brain activity that occurred when it first touched a flap. It turns out that the brain activity changes hundreds of milliseconds before the bird can see the food, which is compelling evidence for memory.
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A population of North Island robins in a New Zealand sanctuary provides a unique system for investigating the memory skills of birds in the wild.
Amy, a former intern at The Scientist, attended Cornell University to study neurobiology and later graduated from the University of Iowa with an MFA in creative writing. She is a Los.
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Above: A Toutouwai opens a lid to reveal a mealworm, which it then consumes. RACHAEL SHAW.
New Zealands North Island robins (Petroica longipes), known as toutouwai in Maori, are capable of remembering a foraging task taught to them by researchers for up to 22 months in the wild, according to a study published on February 12 in Biology Letters. These results echo the findings of a number of laboratory studies of long-term memory in animals, but offer a rare example of a wild animal retaining a learned behavior with no additional training. The study also has implications for conservation and wildlife management: given the birds memory skills, researchers might be able to teach them about novel threats and resources in their constantly changing habitat.
This is the first study to show [memory] longevity in the wild, says Vladimir Pravosudov, an animal behavior researcher at the…
Rachael Shaw, a coauthor and behavioral ecologist at Victoria University in New Zealand, says she was surprised that the birds remembered the new skill she had taught them. Wild birds have so much that they have to contend with in their daily lives, she says. You dont really expect that its worth their while to retain this learned task they hardly had the opportunity to do, and they cant predict that they will have an opportunity to do again.
Shaw is primarily interested in the evolution of intelligence and the cognitive capacities of animals. The toutouwai, which are trainable food-caching birds with a lifespan of up to ten years, are ideal subjects for her behavioral studies. Shaw claims that they possess the same audacity and curiosity as many island bird species. These characteristics make them susceptible to ermines (also known as stoats), rats, and invasive cats. However, they are also curious and comparatively fearless of humans, which makes them the perfect species to test memory retention in the field.
In a previous study published in 2017, Shaw demonstrated that wild toutouwai living in the Zealandia Wildlife Sanctuary in Wellington, New Zealand, are capable of learning a novel task. Using a rectangular box with three compartments, each covered by a lid that swivels to the side to reveal its contents, she incrementally taught the birds how to peck the lids aside and retrieve mealworms hidden inside two of the three wells.
About a year later, Shaw was speaking to the public about conservation and her work with birds at the sanctuary. A toutouwai materialized as she described the memory apparatus she had utilized in her earlier research.
She remembers telling the audience, “I haven’t given this bird this task in over a year, so let’s see how he does.” The bird descended to the device and began opening the lids as if on cue. This made her wonder how many of the other birds were able to complete the memory task successfully and for how long.
A wild toutouwai shows off its memory for a new task. ANNETTE HARVEY.
In the new study, Shaw and her coauthor, Annette Harvey, tested 32 of the initial 64 birds that were trained in 2015 and 2016 and banded for individual identification, 30 of which performed the memory task by spontaneously pecking the lids and opening them on their first try. None of the trained birds had seen the box between the initial training and retesting, though some of the untrained control birds had encountered the apparatus in a previous research project. The time between when the birds had first learned the lid-opening behavior and subsequent testing ranged from 10 to 22 months. By contrast, the 17 untrained birds were unable to complete the task.
Shaw suggests that the two individuals who were not consistent in remembering the task could have been anomalies. Among the trained birds was a female that had learned the task the slowest at first, and whose domineering male partner disrupted the testing. The other bird vanished a few weeks after the experiment because it was elderly and ill.
While Shaw was impressed by her subjects performance, Pravosudov says, Ive been studying these questions for a long time. Its not surprising. Nevertheless, he adds, its good to have more evidence accumulated that the animals are capable of this. For instance, he cites lab studies that have shown pigeons ability to remember and identify photographs and drawings for more than 730 days, and tortoises ability to retain an operant conditioning task for nine years. Lab research on Clarks nutcrackers and chickadees has also found that the birds can remember the locations of hundreds of seeds for six months or more.
He claims that “all animals have some basic memories,” and that “we may underestimate how good even [basic] memory is. .
Tim Roth, a behavioral ecologist at Franklin & Marshall College who completed a postdoc with Pravosudov and did not participate in the research, agrees that we have a lot of information from a lot of different species in a lot of different systems of long-term memory, including decades of social memory in dolphins and long-term memory in turtles based on one-trial learning. But Roth says he also recognizes the value of studying this particular system of wild birds. Its very difficult to get these kinds of opportunistic sorts of observations, he says, where you try to do something at one point in time, and then, hopefully, youll see the same individuals one or two years later.
Toutouwai may be able to remember the task for longer than 22 months, as the study found no correlation between forgetting and the amount of time that had passed since the birds formed the lid-opening behavior. Shaw is interested in determining whether the birds can recall a more complex piece of information, like distinguishing between lids of different colors, which would require them to retain both the lid-opening behavior and the color cue for a prolonged amount of time, in addition to testing additional memory duration.
Caroline Strang, a postdoc who studies animal cognition at the University of Texas at Austin and was not involved in the research, says that this study presents an experimental model that could be emulated by other scientists. This is a population that is being monitored for other purposes, she says, and there are lots of populations of birds and other species that have long-term monitoring in the same way. . . . People who are interested in behavior and cognition can go in and capitalize on that by doing more long-term cognition studies.
Shaw says that in the end, she hopes that these discoveries can be used to safeguard toutouwai against swift environmental change. To that end, she is presently creating a protocol to see if the birds can be trained to identify and stay away from cats. “Teaching them about the dangers of cats before they leave the sanctuary and ensuring that they remember it for a long period could really help in increasing their chances of surviving outside the fence,” she says. .
R.C. Shaw, A. Harvey, Long-term memory for a learned behavior in a wild bird, Biology Letters, doi:10.1098/rsbl.2019.0912, 2020.
Amy Schleunes is an intern at The Scientist. Email her at aschleunes@the-scientist. com.