The effect of the application of the colored light emitting diodes on fruit-foraging behavior in brown-eared bulbuls （Hypsipetes amaurotis）

Abstract

We examined fruit-foraging behavior of brown-eared bulbuls in a cage at the laboratory under the various lighting condition so that our study will help to prevent the damage of fruit produce caused by fruit-eating birds such as bulbuls. We classified eight and seven maturity stages of strawberry and grapes, respectively, in reference to each fruit-color chart. We presented the captive bulbuls with the choice tests of each fruit types at different maturity stages and colored Light Emitting Diode （LED） （red 630nm, yellow 590nm, green 525nm, blue 470nm）was applied to examine the effects of difference lighting condition. Five bulbuls were used for the strawberry choice test. Under the normal fluorescent light （control session）, bulbuls could choose strawberry preferentially in the order of more mature stage. However, when the colored LED was applied, the bulbuls could distinguish immaturity stages （color.0-3） of the strawberry, but not maturity （color.4-5） and post-maturity stages （color.6-7）. Under the each color of the LED, the frequency of the post-maturity stage of strawberry that was first chosen by bulbuls was significantly lower than that in the control. Furthermore, significantly longer latency to choose strawberry at post-maturity stage was observed when the blue LED was applied compared to the control and the other colors. Four bulbuls were used for the grape choice test. Bulbuls could choose grapes preferentially in the order of more mature stage, and there were no significant difference in their eating behavior among the lighting condition. It was shown that we could affect the recognition of the maturity fruit through the color vision of the bulbul by irradiating fruit with the LED light of the specific color that could change a color of the fruit.