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Echolocation calls of Myotis lucifugus and M. leibii (Vespertilionidae) flying inside a room and outside

100%

Mukhida M., Orprecio J., Fenton M. B.

Acta Chiropterologica

2004

tom 06

nr 1

The purpose of this study was to compare the echolocation calls of the same four individual Myotis lucifugus and Myotis leibii flying inside a closed room and when released outside. Echolocation calls were recorded using a Pettersson D980 bat detector, the high frequency output fed into a personal computer via an F2000 Control Filter and an Ines High speed card. Recorded as .wav files, recordings were analyzed with BatSoundPro. We measured call duration (DUR in ms), frequency with maximum energy (FMAX in kHz), highest frequency (HF in kHz), lowest frequency (LF in kHz), and inter-pulse interval (IPI in ms). Multivariate Analyses of Variance (MANOVA) indicated significant differences in call features between species, between settings, between species in each setting, and finally between settings for each individual. Discriminant Function Analyses (DFA) revealed that inside DUR was the most important parameter distinguishing M. lucifugus from M. leibii, with 66.3% correct classification, while outside, the two species were distinguished 78.8% of the time by LF. The data demonstrate that the same individuals flying in confined spaces change the details of their echolocation calls compared to when flying in the open. Calls produced inside are shorter in DUR and are produced at shorter IPIs than calls produced outside. FMAX differed most between the calls of M. lucifugus and M. leibii whether flying inside or outside. Differences between echolocation calls were more pronounced between setting (inside versus outside) than between species.

Data, sample sizes and statistics affect the recognition of species of bats by their echolocation calls

88%

Biscardi S., Orprecio J., Fenton M. B., Tsoar A., Ratcliffe J. M.

Acta Chiropterologica

2004

tom 06

nr 2

Identification of bat species based on analysis of echolocation calls can be affected by the way data are manipulated, the diversity of species, and call variability. We document the effects of sample sizes and a priori assignment of calls by species on the outcome of discriminant function analysis (DFA) and multinomial logistic regression (MLR) of features of echolocation calls, and determine which features of calls are most useful for identification. We used recorded echolocation calls of eight species readily distinguishable by call features, including molossids, emballonurids and a moormopid recorded at sites in Belize, Brazil, and Mexico. On individual calls, we measured four features: frequency with most energy, highest and lowest frequencies and call durations obtained from sequences consisting of 10 calls. Cluster analysis and multiple analyses of variance indicated significant differences between the calls of different species. Outcomes of DFA and MLR were affected by both sample sizes (numbers of calls, numbers of sequences) and the subjective approach that researchers take to their data (i.e., categorizing calls or sequences of calls by species). Levels of variation in calls of some species in our sample often precluded the use of single calls in making call-based identifications. Accurate documentation of variability in echolocation behavior of sympatric bats is a prerequisite for an effective sound-based bat survey

Ograniczanie wyników

2 Acta Chiropterologica

2 Fenton M. B.

2 Orprecio J.

1 Biscardi S.

1 Mukhida M.

1 Ratcliffe J. M.

1 Tsoar A.

2 2004

Wyniki wyszukiwania

Echolocation calls of Myotis lucifugus and M. leibii (Vespertilionidae) flying inside a room and outside

Data, sample sizes and statistics affect the recognition of species of bats by their echolocation calls