2021 Volume 92 Issue 3 Pages 343-349
In this study, we used behavioral techniques to determine whether the sika deer (Cervus nippon) is dichromatic. In discrimination tests, we exposed two sika deer (male and female) to three pairs of colors (red vs. bluish green, reddish purple vs. green, and blue vs. green), which are difficult to discriminate, to represent the three forms of dichromatism （protanopia, deuteranopia and tritanopia) observed in humans. For each color combination, sika deer were simultaneously presented with pairs of color cards in an operant conditioning room, with each session consisting of 20 trials. For each test, the criterion used to define successful discrimination was to make 16 or more choices for color cards presented as positive stimuli out of 20 trials for three sessions in a row (P<0.01, Chi-square test). In discrimination tests for each of the three pairs of colors, sika deer fulfilled the discrimination criterion in the 18th, 5th and 3th sessions in the male, and the 12th, 14th and 4th sessions in the female, respectively. In conclusion, from a behavioral perspective, it was suggested that the color discrimination capability of sika deer does not correspond with dichromatism in humans.
