Does asynchronous fruit ripening avoid satiation of seed dispersers?: a field test

• Published in: Ecology (Durham) 1988-10, Vol.69 (5), p.1545-1551
• Main Author: Gorchov, David L.
• Format: Article
• Language: English
• Subjects: AMELANCHIER; Amelanchier arborea; APETITO; APPETIT; APPETITE; Bird nesting; BIRDS; bombycilla cedrorum; DISEMINACION DE SEMILLAS; DISSEMINATION DES GRAINES; Foraging; FRUIT; Fruit crops; Fruit trees; Fruits; FRUTO; MADURACION; MATURATION; OISEAU; PAJAROS; Plants; Ripening; ROSACEAE; Satiation; SEED DISPERSAL; Trees
• ISSN: 0012-9658; 1939-9170
• DOI: 10.2307/1941652

Asynchronous ripening of fruits within individual, temperate, summer-fruiting, bird-dispersed plants has been proposed to be an adaptation to avoid satiation of dispersers when they are not abundant. I tested a prediction of this hypothesis by manipulating ripening synchrony on individual Amelanchier arborea trees and comparing ripe fruit removal rates from these trees to paired controls. Artificially synchronous ripe fruit displays were created by cutting of unripe fruit and replacing them with ripe fruit. Fruit removal was faster for the manipulated, synchronous tree in three pairs, slower in two pairs, and not significantly different in five other pairs, suggesting that synchronous displays did not satiate dispersers. This unexpected result is attributed to violation of the unstated assumption that dispersers are relatively sedentary in their foraging in the summer and do not concentrate at large fruit displays. In this study the major frugivore of A. arborea, the Cedar Waxwing (Bombycilla cedrorum), foraged widely in flocks of 2-6; other reports reveal that some other frugivorous bird species also forage widely in the summer. This nonterritorial foraging implies that the arrival of dispersers is temporally unpredictable from the perspective of each plant, and it is this temporal unpredictability that may favor asynchronous ripening in plants lacking adaptations for ripe fruit persistence.