On the Use of Tape Recorders in Avifaunal Surveys

The utility of tape recorders and tape playbacks for censusing birds is widely recognized (Johnson et al. 1981), but little emphasis has been placed on their importance in faunal surveys. Tape recorders are indispensable for finding rare, secretive, or patchily distributed species, and for documenting the composition of mixed-species flocks in forest canopy. Awareness of vocal differences in the field and taping has led to the discovery of several taxa new to science (Parker and O'Neill 1985, Parker and Schulenberg MS), and to the recognition of numerous species previously considered subspecies (Lanyon 1967, 1978; Pierpont and Fitzpatrick 1983). One person equipped with a tape recorder and directional microphone can document a surprisingly high percentage of a tropical forest avifauna within 4-7 days during the proper season. Without tape recorders, several weeks (or even months) are required to locate most of the resident bird species in any lowland Amazonian locality, and such an effort would involve a large number of experienced observers using the best optical equipment and many mist nets. On a recent Louisiana State University Museum of Zoology (LSUMZ) expedition to the Department of Pando in Amazonian Bolivia (Parker and Remsen 1987), I tape-recorded 243 species found within an area ca. 2 km 2 of upland rain forest in only seven days. The "final" list of forest birds for the same area, after 54 days of intensive fieldwork (including 36,804 mist-net hours) by seven experienced ornithologists, included 287 species. I tape-recorded 85% of the avifauna in just one week. Ten of the species that I missed altogether were almost certainly visitors to the site, and most of the other species not found were those typically missed during brief surveys of rain forests, such as forest raptors and canopy hummingbirds. In an age when few ornithologists collect specimens, taping is the quickest and most practical way to build an inventory of a diverse avifauna. Locality