We compared the required latency to complete discrimination learning in jungle crows in response to cue stimulations of various light wavelengths. We used 6 types of light-emitting diodes (LEDs), which had single-spectral peaks at 365 nm, 375 nm, 465 nm, 555 nm, 585 nm and 695 nm, respectively. Each type of LED for testing was applied to 3 crows, and a total of 18 crows were tested. Our results showed that the crows took an average of 5.7 days at 365 nm, 5.0 days at 375nm, 4.7 days at 465nm, 7.3days at 555 nm, 10.3 days at 585 nm and 6.3 days at 695 nm before reaching the discrimination criterion (greater than or equal to 75% correct choices in two consecutive sessions; binomial probability test, p<0.05). The average percentage of correct choices for 5 successive days with each LED was 88.3% at 365 nm, 93.6% at 375 nm, 94.3% at 465 nm, 82.7% at 555nm, 85.0% at 585 nm and 88.3% at 695 nm. These results suggest that the shorter wavelengths (less than 465 nm) induced greater learning intensity compared with longer wavelengths.

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