Display size preferences and foraging habits of high andean butterflies pollinating Chaetanthera lycopodioides (Asteraceae) in the subnival of the central Chilean Andes

In our study, we asked whether butterflies visiting Chaetanthera lycopodioides (Asteraceae) in the subnival at 3450 m a.s.l. in the central Andes prefer larger floral displays. To answer this question, we compared the population distribution of display sizes with the distribution of visited display sizes at two sites. Six high elevation butterflies: Faunula leucoglene (Satyridae) (the dominant species), Hylephila sp. (Hesperiidae), Phulia nymphula (Pieridae), Vanessa terpsichore (Nymphalidae), Tatochila mercedis (Nymphalidae), and Yramea modesta (Nymphalidae) were reported as visitors. Butterflies tended to discriminate against plants with a single open head, preferring larger display sizes at both sites. Butterflies visited few plants per bout (mean: 3.1-4.5) and probed increasingly smaller proportions of the open heads per plant with increasing display size (overall mean: 45.8-48.4%). Results suggest that high elevation butterflies tend to prefer larger display sizes over smaller ones, but final choices are conditioned by the relative abundance of each display size in a population. Although previous studies show that butterflies prefer larger artificial individual flowers over smaller ones, our work appears to constitute the first report of butterfly preference for larger floral displays in any plant species or ecosystem.