Diel, seasonal, and species-specific trends in vocalizations of dolphins in the Gulf of Mexico /
Seven acoustic surveys in the north-central Gulf of aphics.
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1998.
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| Subjects: |
| Summary: | Seven acoustic surveys in the north-central Gulf of aphics. Mexico were conducted over one and one-half years, from spring 1992 through fall 1993. Of the 70.17 hours of recorded delphinid vocalizations, 27.25 hours were recorded during the day and 42.92 hours were recorded at night. Forty-seven percent of daytime recordings were from 11 identified species; whereas, only 3% of nighttime recordings were from identified species, which numbered only four. From day to night, there were significantly more whistles (x2 = 3395.58; D.F. = 6; p <0.001), click trains (/ = 388.52; D.F. = 6; p <0.001), and burst pulses (z2 = 198.35; D.F. = 6; p <0.001). Proportions of the signal types, defined as the number of one signal type compared to total number of all signal types, were examined. The proportion of whistles decreased at night (U = 3.0; p < 0.05), and the proportion of click trains increased at night (U = 2.0; p < 0.05). However, the proportion of burst pulses was the some between day and night (U = 10.0; p > 0.05). Diversity of whistles (whistle types based on spectrogram contour shape) differed between day and night (t = 2.358; p < 0.05). Measured time and frequency parameters of whistles included peak time, peak frequency, duration, beginning frequency, end frequency, bandwidth between beginning and end frequencies, high frequency, low frequency, and bandwidth between high and low frequencies. A significant difference in time and frequency parameters of whistles occurred during summer compared with those during spring, fall, and winter. Whistles were analyzed for seven of the dolphin species, and whistle parameters differed significantly among species. There also was a diet difference in whistle bandwidth between high and low frequencies at = 12.353: 17 < 0.0011. |
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| Item Description: | "Major subject: Wildlife and Fisheries Sciences". Vita. |
| Physical Description: | x, 73 leaves : illustrations ; 28 cm. |
| Bibliography: | Includes bibliographical references: pages 57-72. |