Stereotyped Calling Patterns of a Male Weddell Seal (Leptonychotes weddellii)
Paraphrased from the Materials and Methods of the referenced paper: In early December 1997, we conducted an opportunistic study of the transmission of underwater calls through sea ice. Simultaneous recordings were made underwater and above the ice near a breathing hole. A male seal (identified by hi...
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Australian Ocean Data Network
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| Online Access: | https://researchdata.ands.org.au/stereotyped-calling-patterns-leptonychotes-weddellii/686341 https://data.aad.gov.au/metadata/records/ASAC_2122-5 https://data.aad.gov.au/eds/1495/download https://secure3.aad.gov.au/proms/public/projects/report_project_public.cfm?project_no=2122 https://data.aad.gov.au/eds/2509/download http://data.aad.gov.au/aadc/metadata/citation.cfm?entry_id=ASAC_2122-5 |
| Summary: | Paraphrased from the Materials and Methods of the referenced paper: In early December 1997, we conducted an opportunistic study of the transmission of underwater calls through sea ice. Simultaneous recordings were made underwater and above the ice near a breathing hole. A male seal (identified by his use of trills) frequented the breathing hole during the two days that recordings were obtained. In addition to recording sound levels of the underwater calls just above the ice, the in-air microphone recorded the breathing sounds when the seal surfaced in the hole. it seemed likely that all of the recordings were from a single adult male Weddell seal. Recordings were made on landfast sea ice (68.5699 degrees S, 77.9266 degrees E), 1.55km from the shoreline of Davis Station, Eastern Antarctica, on 1 and 8 December 1997. The water depth was 23 m. The ice in this area had been broken up and refrozen following the arrival of the R.S.V. Aurora Australis to the station two months earlier. Recordings were made on an opportunistic basis at two different breathing holes (one per day). Simultaneous recordings in air (using a Radio Shack 33-2050 sound level meter as a microphone) and underwater (Bruel and Kjaer 8100 hydrophone with a Bruel and Kjaer 2635 charge preamplifier) were made using a Sony TCD-D7 DAT recorder. The microphone was 1.0 to 3.0 m from the breathing hole, and the hydrophone was deployed through the breathing hole to a depth of 3.0 to 3.8 m. To reduce possible human disturbance, 2 hour DAT tapes were used and after the equipment was operating, the observer left the area. From the abstract of the attached paper: Underwater calling behaviour between breathing bouts of a single adult male Weddell seal (Leptonychotes weddellii) was examined with respect to call type and timing late in the breeding season at Davis Station, Antarctica. Underwater calls and breathing sounds were recorded on 1 and 8 December 1997. Thirty-seven sequences of calls prior to surfacing to breathe and 36 post-submerging sets of calls were analysed with respect to probability of call type occurrence and timing. Dives were 461 plus or minus 259 seconds (mean plus or minus standard deviation). The seal called every 29.7 plus or minus 56.2 seconds throughout a dive. The first call after submerging was usually (n = 29 of 36) a low frequency (less than 0.8 kHz) growl. Three patterns of three- to five-call type sequences were made following 28 of 36 breathing bouts. Call type patterns after submerging exhibited fewer different sequences than those before surfacing (chi-squared = 61.42, DF = 4, p less than 0.000001). The call usage patterns before surfacing were diverse and did not indicate when the seal was going to surface, a time when he would be vulnerable to attack from below. Our findings suggest the hypotheses that territorial male Weddell seals call throughout each dive and use stereotyped call patterns to identify themselves while vocally asserting dominance. This work was completed as part of ASAC project 2122 (ASAC_2122). The fields in this dataset are: Tape number Sequence per tape Sequence entire data Call types Count since last breath Last breathing bout number Count prior to next breath Time in tape (seconds) End time of last breath Start time of next breath Time since dive The 'sequence' relates to the sequence of call types that are given between the end of the last breath of a breathing bout and the beginning of the first breath the next time the seal surfaces to breathe. Essentially the report relates to the stereotyped nature of the call types, especially just after the dominant male dives after finishing breathing. Each time the animal surfaced, that was identified as a breathing bout. They are numbered sequentially. At the very start of the data set the seal had to surface before the breathing bout could be counted (as number 1). This procedure enabled us to identify the order and timing of the calls that occurred immediately before and immediately after each breathing bout. Thus, the 'count prior to the next breath' gives the order of the calls before the seal surfaced to breathe again (third last, second last, last,). The call types were analysed with respect to the following pattern: third last, second last, last, breathing bout, first, second, third, etc. to third last, second last, last, next breathing bout. |
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