NEIGHBORHOOD EFFECTS ON FRUIT REMOVAL BY BIRDS - A FIELD EXPERIMENT WITH VIBURNUM-DENTATUM (CAPRIFOLIACEAE)

Manipulated northern arrowwood fruit density in C New York, then monitored fruit removal by birds during 14 wk in the fall of 1985. Each plot had either high or low fruit density in a central 1 m diameter "crop' area, and either high or zero "neighborhood' fruit density in the rest of the 100 m2 plot. Fruits in high density neighborhood plots were removed significantly faster than fruits in plots with zero density neighborhoods. A significantly lower proportion of marked fruit was removed from plots with both low crop size and zero density neighborhoods. Some 43% of all removal of marked fruit by birds took place during a 2-wk period early in the fruiting season. Birds feeding in flocks fed in high density neighborhood plots almost exclusively, presumably causing the greater removal from these plots. Fruit abscission accelerated after week 9, and by week 14 no fruits were left on plants. White-tailed deer Odocoileus virginianus consumed 400 of the 750 marked infructescences during the 14 wk, but destroyed rather than dispersed seeds. -from Author