When foraging for food in the wild, birds have to weigh a number of factors before deciding whether to attack, like the nutrient content of a given prey, or whether a certain insect might possess chemical defenses that make it taste gross. To navigate this minefield of good and bad snacks, some birds take cues from their buddies—and according to a new study in the journal British Ecological Society, watching videos are enough to help birds learn to avoid nasty foods.
Scientists at the Konnevesi Research Station in Central Finland carried out this intriguing experiment on two species that are common in woods, forests, parks and farmland: the great tit (Parus major) and the blue tit (Cyanistes caeruleus). These species tend to forage together and have similar diets, providing a good opportunity to study how the birds might learn from both members of their own species and members of other species. Previous research has shown that great tits are pretty good at learning to avoid certain foods based on the “disgust responses” of other predators. But among blue tits, according to the study authors, “the evidence for social information use is less clear.”
The researchers tested 30 great tits and 48 blue tits captured from a feeding site at the research station. They showed each feathery test subject a video of another bird’s responses to tasting a selection of almond flakes; some of the nuts were completely fine, others had been soaked in a bitter-tasting solution. The yummy almonds were wrapped in a white packet stamped with a black cross, while the yucky ones were labelled with squares.
In the videos, birds could be seen vigorously wiping their beaks and shaking their heads after eating the bitter almonds. The clips featured both great tits and blue tits. When their TV-watching sessions were finished, the test subjects were introduced to a new environment containing both cross- and square-marked prey items. Groups of 12 great tits and 12 blue tits who had not watched the videos were presented with the same food options, reports Bethan Ackerley of New Scientist.
Birds that had watched the videos ate fewer of the icky prey packets than those that had not, the researchers found. Blue tits seemed to learn better after watching videos featuring members of their own species, while great tits performed similarly regardless of what species had been featured in the videos.
In the wild, certain insects—like ladybugs and tiger moths—boast clear markings warning birds that they are not going to taste good. But “naive, uneducated predators” have to learn to avoid these prey, notes study author Liisa Hämäläinen, who was a Ph.D. student in the University of Cambridge's Department of Zoology when the experiment was carried out.
“By watching others, [great tits and blue tits] can learn quickly and safely which prey are best to eat,” Hämäläinen says. “This can reduce the time and energy they invest in trying different prey, and also help them avoid the ill effects of eating toxic prey.”
The researchers cannot, however, be entirely sure what social cues are most important to birds in the wild. Watching more seasoned birds avoid certain prey, for instance, might be just as salient as observing visible signs of disgust. “The situation is likely to be more complicated in the wild,” the study authors note, because birds will encounter many different types of prey and have ample opportunities to learn from both members of their own species and members of other species.
In spite of these limitations, the new study suggests that social transmission is an essential component of predator learning—even when those lessons are being broadcasted to our avian friends from a screen.