[pp.61-68]

Effects of Environmental Structure on Beak Marks found on Butterflies

Masato OTA, Masahide YUMA and Yuki TOGO （Ryukoku University）

Abstract:
Beak marks on butterfly wings have been used as an indicator of predation pressure. Habitat structure, such as canopy height, is predicted to affect predator foraging behavior. However, the effects of habitat structure on the prey?predator interactions between butterfly species and their predators have not been well documented. In this study, we examined the relationship between environmental structure and beak marks on butterfly wings in the field to explore how differences in habitat influenced predation pressure. We used transect censuses to measure the beak mark rate on butterflies from May to November, 2010, in Shiga Prefecture, Japan. Analyses of butterfly species composition among the study sites showed a high similarity between Rokuha Park and Ryukoku Forest, while the species composition in Ichiriyama was different from the others. In contrast, the species composition of butterflies with beak marks was similar between Rokuha and Kawabe parks as well as between Ichiriyama and Ryukoku Forest. These differences may be due to the differences in canopy openness in the forest zones in Rokuha Park and Ryukoku Forest. The species composition of butterflies with beak marks was different even among sites with similar butterfly faunas and predator densities, indicating that butterfly?predator relationships might differ depending on environmental conditions.

Key Word:
beak mark, environmental structure, prey–predator relationship

PDFダウンロード（会員限定）