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Description and Identification of the Echolocation Calls of Leptonycteris nivalis and Other Nectar Feeding Bats in Mexico
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The conservation of nectar-feeding bats is critical for preserving arid, semi-arid and desert ecosystems, in addition to the genetic diversity of some ecologically and economically important plant species. In the northern region of Mexico, in particular, some of the species that have been affected by the disruption of the pollination dynamics are Leptonycteris nivalis, Choeronycteris mexicana, Leptonycteris yerbabuenae, and Antrozous pallidus. In this study, I aim to identify and describe the echolocation call of the four active gleaning forager species with the purpose of providing a passive acoustic monitoring technique. I measured and assessed over 70 parameters and employed a PCA to determine the minimum number of variables that best described and allowed identification of species. A Kruskal-Wallis followed by pairwise comparisons was used to determine if there were statistically significant differences between the species and identify the most reliable descriptive variables for species segregation. In addition to the description of the echolocation call sequences, I analyzed data of A. pallidus and L. yerbauenae collected from different localities in the northern portion of Mexico to measure potential geographical variation. To assess geographical variations, I employed a MANOVA for each species to assess multivariate differences among regions. The results suggest that the nine predictor variables which best described the calls and segregated between species are the Bndwdth, HiFreq, LowFreq, CallDur, Fc, FreqKnee, DominantSlope, SteepestSlope, and LowestSlope of the calls. An LDA demonstrated that sufficient variability did exist among the groups to accurately discriminate calls among species. The multiple comparisons analysis results suggest that the discriminant variables that best segregated the calls by species were FreqKnee, HiFreq and LowFreq for A. pallidus; Bndwdth and CallDur for L. yerbabuenae; DominantSlope, SteepestSlope and LowestSlope for L. nivalis; and LowestSlope for C. mexicana. The results of the MANOVA comparing L. yerbabuenae calls among the different locations were not significant. Meanwhile for the species A. pallidus the results of the multivariate analysis of variance tests on the ten predictor variables comparing the call structure differences among the were significant for all logarithmic transformed variables. The changes in call structure followed a cline from West to East.
Rivera, Jaileen (2020). Description and Identification of the Echolocation Calls of Leptonycteris nivalis and Other Nectar Feeding Bats in Mexico. Master's thesis, Texas A&M University. Available electronically from