Relationship between fruit ripening and avian fruit removal in Prunus jamasakura

Abstract

To determine how fruit ripening influences fruit removal by birds, we investigated the relationships among fruit color, nutrition value, and avian fruit removal during the fruit ripening period of Prunus jamasakura. Fruit maturing process was divided into 4 phases on the basis of fruit color: green, green-red, red, and black. Green and green-red fruits were smaller, with lower sugar content (i.e., fructose, glucose, and sucrose) and energy levels than those of red and black fruits. Most of the fruits removed by birds were red and black fruits and birds especially preferred black fruits. Black fruits contained more sugars and energy than red fruits. Differences in sugar concentration and energy between them were approximately 4.6% and 0.4kJ, respectively. Gray starlings Sturnus cineraceus and brown-eared bulbuls Hypsipetes amaurotis were the predominant birds visits to the focal tree. The number of gray starling visiting the focal tree increased during the period of the bicolored display from the contrasting colors of ripe and unripe fruits. However, the number of brown-eared bulbul did not appear to change throughout the fruiting period. These results indicate that the bicolored display serves as an effective means of attracting birds; however the effect differed between bird species.