A New Examination of Echolocation Calls of Some Neotropical Bats (Emballonuridae and Mormoopidae)

Abstract

In northwestern Belize, two emballonurids (Rhynchonycteris naso and Saccopteryx bili­ neata) and three monnoopids (Pteronotus pamellii. P. davyi, and P. personatus) were examined acoustically with the Anabat II bat detector and associated analysis system. R. naso used calls consisting of a short constant frequency (CF) at 47 kHz and concave downward frequency modulated (PM) sweep to ca. 40 kHz with two strong hannorucs. Echolocation sequences of S. bilineata revealed a paired cadence of calls. Both signals in a pair slowly increased in frequency, fonning a quasi-CF (QCF) component and tenninated with a short, downward PM sweep. The initial call of a pair ranged from 44.5 to 46.6 kHz and the second ranged from 46.6 to 48.7 kHz. P. parnellii used a long CF call at 63.5 kHz, with a tenninal downward PM sweep to ca. 54.5 kHz. P. davyi produced calls with an initial short CF at 68.1 kHz, a downward PM sweep, and a tenninal short CF at 58.0 kHz. P. personatus emitted calls similar in shape to P. davyi, with the initial CF at 83.0 kHz and the terminal CF at ca. 68.0 kHz. Previous descriptions of echolocation calls for these species compare favorably with those obtained in this study, but the Anabat equipment generally revealed more variation and detail than previously described. The echolocation calls described in this study provide precise vocal signatures for the accurate identification of free-flying individuals of the species studied. The recording and description of echo­ location calls of some Neotropical bats be­ gan with the pioneering work of Griffin (1953) and Griffin and Novick (1955). Al­ though data gathered were surprisingly good, technological limitations prevented recording under a variety of field condi­ tions. Thus, much of the early descriptions of vocalizations were generated from cap­ tive bats. Bats of the families Emballonur­ idae and Mormoopidae tended to produce high-intensity sounds that were easier to de­ tect and record than the low-intensity, high­ ly directional sounds produced by bats in the Phyllostomidae. Subsequent examina­ tion of some of these species. using im­ proved equipment, resulted in more defini­ tive descriptions of echolocation calls (Novick, 1963; Pye, 1973), although the