Are Corvids Feathered Apes?

Although the common ancestor of birds and mammals lived over 280 million years ago, there are striking similarities in the cognitive abilities of members of the crow family (corvids) and primates; including tool manipulation, social reasoning and complex memory. Corvids are perhaps best known for their extraordinary feats of spatial memory. Clark’s nutcrackers, for example have been suggested to cache up to 33,000 seeds in thousands of different sites during a season, and to accurately recover a high percentage of those caches, even when critical features of the environment have changed, such as they are covered in snow (Balda & Kamil, 1992; Balda & Turek 1984; Vander Wall, 1982). There is more to the corvids, however, than just a sophisticated spatial memory. Folklore and legend, particularly in the Vikings and the North American Indians has long suggested that crows, magpies, rooks and ravens may be the most intelligent of birds (Savage, 1997) and recent research is beginning to investigate this long-held view in the laboratory.

In this chapter, I propose that corvids are not only amongst the most intelligent of birds, but that they may also rival the great apes in cognitive ability. I will review the evidence for this proposal in this chapter. By the end, I will conclude that corvids should perhaps be considered as ‘feathered’ apes. This proposal is, at first, a startling claim given that corvids have much smaller brains than the great apes, with the relative absence of cortical structures. This line of thinking has not been the result of deficits in great ape cognition in comparison to corvids, but rather to three points; the claim for ‘special status’ to the apes based on their evolutionary relationship to humans, a reluctance to embrace ecological validity in the design of primate experiments, and the relative lack of studies on avian cognition.