No abstract

No abstract

No abstract

A distinctive vocalization of the sperm whale, Physeter macrocephalus (=P. catodon), is the coda: a short click sequence with a distinctive stereotyped time pattern [Watkins and Schevill, J. Acoust. Soc. Am. 62, 1485-1490 (1977)]. Coda repertoires have been found to vary both geographically and with group affiliation [Weilgart and Whitehead, Behav. Ecol. Sociobiol. 40, 277-285 (1997)]. In this work, the click timings and repetition patterns of sperm whale codas recorded in the Mediterranean Sea are characterized statistically, and the context in which the codas occurred are also taken into consideration. A total of 138 codas were recorded in the central Mediterranean in the years 1985-1996 by several research groups using a number of different detection instruments, including stationary and towed hydrophones, sonobuoys and passive sonars. Nearly all (134) of the recorded codas share the same "3+1" (/// /) click pattern. Coda durations ranged from 456 to 1280 ms, with an average duration of 908 ms and a standard deviation of 176 ms. Most of the codas (a total of 117) belonged to 20 coda series. Each series was produced by an individual, in most cases by a mature male in a small group, and consisted of between 2 and 16 codas, emitted in one or more "bursts" of 1 to 13 codas spaced fairly regularly in time. The mean number of codas in a burst was 3.46, and the standard deviation was 2.65. The time interval ratios within a coda are parameterized by the coda duration and by the first two interclick intervals normalized by coda duration. These three parameters remained highly stable within each coda series, with coefficients of variation within the series averaging less than 5%. The interval ratios varied somewhat across the data sets, but were highly stable over 8 of the 11 data sets, which span 11 years and widely dispersed geographic locations. Somewhat different interval ratios were observed in the other three data sets; in one of these data sets, the variant codas were produced by a young whale. Two sets of presumed sperm whale codas recorded in 1996 had 5- and 6-click patterns; the observation of these new patterns suggests that sperm whale codas in the Mediterranean may have more variations than previously believed.

An inexpensive animal recording and tracking system was designed, which uses sound-recording buoys deployed at several locations simultaneously in a passive hydrophone array. Each buoy contains a global positioning system ͑GPS͒ Location logger, a stereo digital audio tape ͑DAT͒ recorder with a hydrophone connected to one channel, and a VHF radio signal for time synchronization connected to the second channel. In a calibration test, three buoys were deployed in triangle formation at 1.8-km spacing. Light bulb implosions were localized to an accuracy of 60 m at the array center. These buoys are far less expensive than most marine acoustic tracking systems. The instrument package can be used for drift, moored, or terrestrial applications.

In recent years new impetus has been put into cetacean research in the Mediterranean Sea. Specific instruments and software packages were developed, including a high-quality towed array of hydrophones, with its own amplifier and filtering unit, a portable Digital Signal Processing Workstation (DSPW) with real time analysis and file processing capabilities and an Interactive Digital Sound Library (IDSL).Cetacean sounds were recorded in their natural environment from auxiliary sailing vessels up to 26 m long; sounds from six odontocete and one mysticete species were recorded, analyzed, catalogued and organized in a sound library in order to allow flexible and specific access to sound information for research and other purposes such as environmental monitoring, species identification, censusing activities and educational applications.

No abstract

Sperm whales, Physeter macrocephalus(catodon), emit short click sequences, called codas, with regular time patterns [Watkins and Schevill, J. Acoust. Soc. Am. 62, 1485 (1977)]. Since codas recorded in different geographical areas have different and stable patterns, they possibly serve to convey regional information. More than 120 codas were recorded in the Central Mediterranean Sea in the years 1985–1996 by several research groups using a number of different detection instruments, including stationary and towed hydrophones, military sonobuoys and passive sonars. All of the recorded codas share the same time pattern 3+1 (///-/) with an overall duration ranging from 456 to 1280 ms and an average value of 910 ms. Even if the coda duration varies, the click pattern remains significantly stable. In the present work, the repetition rate and time pattern of Mediterranean codas are characterized, also taking into consideration their possible biological and geographical role. [Work supported by the Italian Ministry of the Environment, Inspectorate for Sea Protection, and by the Italian Navy. Work of the second author supported by ONR Base funding at NRL.]