Seeing Is Feeding for the Frugivorous Bird Brown-Eared Bulbul (Microscelis amaurotis)

Figure 1

This study design figure shows a cluster of grapes suspended from a perch. Three basic test methods were used: (1) no bag present (uncovered); (2) half covered/half-visible grape cluster (half-visible bag); and (3) the entire cluster of grapes inside a white bag (full bag). The illustration shows a “half-visible bag,” with the upper half white (black shaded in this figure) and the lower half made of clear film. The white paper bag covered grapes like a skirt; therefore, the birds could look into the white paper bag through the clear film (the lower half bag). Full bags were completely made of white paper. Birds fed on uncovered grapes but could not feed directly on grapes that were covered in the “half-visible bag” or the “full bag.”