FRUIT COLOR CHOICES OF CAPTIVE SILVEREYES (ZOSTEROPS LATERALIS)

Fleshy fruits occur in many colors in nature, but red and black predom inate. One popular hypothesis to explain the adaptive significance of fruit coloration is that it attracts frugivorous birds that disperse s eeds. We presented Silvereyes (Zosterops lateralis), important fruit c onsumers in southern Australia, with choices in the aviary between bot h artificial fruits (made from gelatin) and actual fruits (Rhagodia pa rabolica) of three different colors (red, yellow and white). Silvereye s exhibited a strong overall preference for red among both artificial and real fruits. Although individual birds varied in their color prefe rences for artificial fruits, all preferred the red fruits of R. parab olica. The consumption rate of real fruits was much greater than that of artificial fruits, which was probably attributable to differences i n the characteristics of the two fruit types. Exposure of Silvereyes t o a maintenance diet of a particular color for 12 days also failed to alter their collective preference for red fruits. Further, responses t o artificial infructescences offering color choices either between or within infructescences showed that Silvereyes preferred red fruits reg ardless of the spatial format of presentation. The overall fruit color preferences of Silvereyes were based on selection of hue rather than brightness, but within the same hue, some individuals exhibited prefer ences for particular brightness levels. These results are consistent w ith the hypothesis that fruit color is related to avian frugivory and suggest that birds can act as strong selective agents on fruit color.