By four-months-old the cognitive performance of ravens may be similar to that of adult great apes, a study suggests.
The birds’ performance in experimental tasks testing their understanding of the physical world and how they interact with other ravens was analysed by researchers.
They tested the cognitive skills of eight hand-raised ravens at four, eight, 12 and 16 months of age using a series of experiments.
The skills the authors investigated included spatial memory, object permanence – understanding that an object still exists when it is out of sight – understanding relative numbers and addition.
Scientists also looked at the ability to communicate with and learn from a human experimenter.
According to the study published in Scientific Reports the cognitive performance of ravens was similar from four to 16 months of age, suggesting the speed at which their cognitive skills develop is relatively quick and near-to-complete by four months of age.
At this age they become more and more independent from their parents and start to discover their ecological and social environments, researchers say.
Although task performance varied between individuals, the ravens generally performed best in tasks which tested addition and understanding of relative numbers. They performed worst in tasks testing spatial memory.
The researchers compared the cognitive performance of the ravens with those of 106 chimpanzees and 32 orangutans who completed similar tasks in a previous study.
They found that with the exception of spatial memory, the cognitive performance of the ravens was very similar to those of orangutans and chimpanzees.
Simone Pika from the University of Osnabruck, Germany and her colleagues, say the findings suggest ravens, similarly to great apes, may have evolved general, sophisticated cognitive skills.
The authors propose the birds developed these skills in response to living in a constantly changing environment where survival and reproduction are reliant on cooperation and alliances between ravens.
However, the authors caution that the performance of the ravens studied may not be representative of the species in general.
The paper says: “Here, we provide the first quantitative, large-scale investigation of physical and social cognitive skills in a large-brained songbird species – ravens.”
The authors continued: “The results enabled the first direct, quantitative comparison with the cognitive performance of individuals of two great ape species, chimpanzee and orangutans, tested across the same domains and tasks.
“Our results suggest that ravens are not only social intellects but have also developed sophisticated cognitive skills for dealing with the physical world.
“Furthermore, their cognitive development was very rapid and their cognitive performance was on par with adult great apes’ cognitive performance across the same cognitive scales.”