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SEPG 2046 - Date Awarded 2002
Estimating the Abundance of Tropical Fruit-feeding Butterflies
Nick J.B.Isaac
Abstract
•Butterflies were sampled in baited traps for three months in Panamanian rainforest. A total of 69 species were captured in baited traps.
•Analysis of space use by individual butterflies suggests that most fruit-feeding butterflies have small home ranges in the order of a hectare, although some species undoubtedly use considerably larger areas.
•I was able to estimate population densities for 24 species using mark-recapture techniques. These population densities were correlated with raw capture frequencies, but half the variance was unexplained. Species of the same actual density may vary in capture frequency by an order of magnitude.
•Much of the remaining variation in trapping frequency is explained by taxonomic differences.Morphine and Satyrine butterflies are much more likely to be trapped than species of other subfamilies.This pattern
may be related to differences among subfamilies in flight behaviour and activity pattern. However, species’ trappability is unrelated to body size.
•These findings are supported by a comparison of trapping with transects. Some of the most frequently trapped species were never observed on transects, and vice versa. However, the number of species shared between the two methods is consistent with the size of the total species pool.
•I found evidence of a temporal shift in community composition between wet and dry seasons. On a finer scale,most of the common species were found to vary significantly in abundance from one week to the next.
•These findings are discussed in relation to the use of baited traps in community ecology and biodiversity studies.
Full report: SEPG2046
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