Male Hypolimnas bolina (L.) (Lepidoptera: Nymphalidae) defend perch sites as a method of visually locating receptive females. In this study we charted the spatio-temporal activity of perching males in tropical Australia to investigate (a) the extent to which male activity is thermally constrained, and (b) the physical attributes of selected perching sites. Butterflies were surveyed along two 5-15 m wide open corridors through dense vegetation, and this allowed the prediction that males should favour narrower corridor sections in order to maximize their visual search capability. This prediction was supported. Beyond corridor width, the distribution of favoured perches was not explained any further by patterns of shading, larval food plant distribution, or the presence of nectar resources. Males were active from 0800 to 1700 h, but the number of perching individuals varied throughout the day, and this pattern varied between the two transects. Most individuals perched along one transect in the morning (0900-1100 h), whereas activity along the other peaked around midday (1100-1300 h). This between-transect difference in male activity followed changes in shading between the transects, however this variable did not predict male distribution at the territory scale. Although ambient and black body temperatures were significantly related to population-level activity, these variables only predicted 15-55% of the variance in male counts in individual transects. This result, viewed in conjunction with the limited available information on female receptivity, suggests that the timing of mate location in H. bolina may be primarily influenced by the daily pattern of female availability.
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