The fine-grained spatial abilities of three seed-caching corvids.

We used a psychophysical method to examine the ability of three corvid species to discern fine-grained spatial information. Nutcrackers, pinyon jays, and scrub-jays were required to discriminate the distance between two landmarks on a computer screen in an operant chamber. All three species were able to discriminate between arrays that differed by 20 mm; the discrimination gradients for scrub-jays and pinyon jays were sharper than those for nutcrackers, however. The results suggest that differences in spatial memory among these species are not related to differences in fine-grained perception.