A recent study of a variety of parrots, from the large green-winged macaw to the tiny spectacled parrotlet, reveals that the way the birds approach a problem involving strings — more specifically, how to acquire food at the end of the string — provides a view inside the minds of many of our favorite parrot species.
The research study done by Anastasia Krasheninnikova of the Zoological Institute and Museum at the University of Hamburg, Germany, says that most of the research on bird intelligence focuses on one species and tests it with many different experiments. Her research compares performance across species to discover if cognitive abilities evolve as a result of selection (e.g. through socio-ecological factors). Put very simply, where a species is from and how it relates to other birds may have an effect on how "intelligent" it is, or how "intelligent" is has to be to survive.
"The prediction here is that even closely related species may differ largely in their cognitive abilities if they are exposed to very different selection regimes," Krasheninnikova said. "Alternatively, cognitive ability may be kept once evolved and remain in a lineage even after speciation events. This implies that some species may possess highly developed cognitive skills even though they are not required and not used in their ecological or social environment. Comparing specific cognitive performance across a wide range of different species is an important tool in animal cognition research and can lead to a better understanding of the mechanisms underlying the evolution of cognition."
The parrots in Krasheninnikova’s study had five tasks to complete, each progressively more complex. In the first, the parrots had to pull a suspended string with food on the end. The second test required the parrots to choose the one of two strings that had food on it. In the third test, the strings were crossed, and only pulling the correct side would result in acquiring the food. In the fourth task, the string extended to the ground, so the parrot could choose to either pull up the string or climb down to get the food. In the final task, two strings had food at the end, but one had a gap between the string and the food, requiring the parrot to choose the string that would give the reward.
"I tested many different species: several cockatoos, macaws, parrotlets, Amazons, lorikeets and parakeets," Krasheninnikova said. "These species were chosen based on their social and ecological systems, and their phylogenetic relationships. Some differ in their ecology or social structure, but are closely related to each other; others occupy similar ecological niches or live in groups with similar social organization, but are only distantly related to each other. This allows us to explore which socio-ecological parameters may lead to different cognitive adaptations and therefore may be the selective pressure driving the evolution of cognition in animals."
Who was the clear winner? The spectacled parrotlets were the only species to complete all five tasks. The green-winged macaws were the most impatient, pulling strings by chance, and did not complete tasks four or five. The lorikeets placed somewhere in the middle. The presumption is that the social structure of the birds determined how they chose to complete the tasks. Parrotlets live in large flocks and experience a variety of social relations; green wings live in small, familial groups.
"My research is not finished yet, however, the first results led to the assumption that there is variation in the parrots’ ability to solve patterned-string problems and that living conditions may have favored specific abilities needed to solve such problems,” Krasheninnikova said. "At the moment, I continue to analyze which selective pressures could be responsible for this variation and use a larger number of species. Things keep getting more and more interesting."