Who are the smart birds?

To understand the evolution and function of cognition, it is important to know the breadth of species demonstrating a variety of cognitive abilities. Statements in scientific and popular literature commonly assert that avian species in the corvid and parrot families are the most intelligent. While this could be true, it is unclear whether there is sufficient data from a diversity of taxa to support this claim. Additionally, this bias could further reduce diversity of studied species by leading to a preference for choosing corvid and parrot species for cognition studies. To evaluate trends in avian cognition research, I reviewed published experimental studies from the last 25 years to quantify species that have been tested for any cognitive ability. Current research encompasses less than 30% of families and 2% of species. The most studied family was Corvidae, followed by Columbidae, Paridae, Phasianidae and Psittacidae. Species from these top five families comprised 64% of studies, illustrating a bias towards these families for avian cognition research. There was also a bias in the focal species for testing different categories of cognitive ability. Traditional lab species from Columbidae and Phasianidae were primarily tested for fundamental cognition, while Corvidae and Psittacidae were more frequently tested on social cognition. Thus, current research tests for the presence of cognitive abilities assumed to lead to “smart” behaviors primarily in species that we already assume are the smartest. Despite accelerating research interest in this field, this biased sample of focal species and cognitive abilities precludes inferences about the cognitive superiority of any species or the characteristics favoring the evolution of cognition.