Techniques and Guidelines for Monitoring Neotropical Butterflies

Long-term monitoring of selected species can identify changes in biological diversity, permitting the timely adjustment of management activities to reverse or avoid undesired trends. This paper addresses several related issues bearing on the development of inexpensive and easily implemented monitoring programs for tropical butterflies. First, we discuss the use of butterflies as ecological indicators. Next, we present field evaluations of butterfly sampling techniques, indicating that: (1) light-gap size greatly affects sampling results in forests and should be of critical concern in site selection and sampling design; (2) baited traps and visual censuses provide complementary data on butterfly abundances; (3) monitoring a subset of locally common butterfly species can provide data for comparing community composition and relative abundance of species in areas where species inventories are incomplete. Drawing on these results, we develop guidelines for designing monitoring programs. These address the formulation of explicit questions to be addressed through monitoring and the selection of appropriate study sites, study species, sampling techniques, and sampling frequency. A protocol for the ongoing butterfly monitoring program that emerged from these studies is appended. The techniques and guidelines presented here are intended to serve as an adaptable model for biologists designing monitoring projects to help guide applied conservation efforts in the tropics.