Variation of in-air female Weddell seal contact calls
Acoustic data collection: Weddell seal female calls were recorded from four breeding sites, Weddell Arm (WA), Partizan Island (PI), Long Fjord (LF), and Topografov Island (TI), near Davis Station, Antarctica in November 1997. Routine recordings were made between noon and midnight in good weather con...
| Other Authors: | , |
|---|---|
| Format: | Dataset |
| Language: | unknown |
| Published: |
Australian Ocean Data Network
|
| Subjects: | |
| Online Access: | https://researchdata.ands.org.au/variation-in-air-contact-calls/686340 https://data.aad.gov.au/metadata/records/ASAC_2122-4 http://data.aad.gov.au/aadc/portal/download_file.cfm?file_id=1956 https://secure3.aad.gov.au/proms/public/projects/report_project_public.cfm?project_no=2122 http://data.aad.gov.au/aadc/portal/download_file.cfm?file_id=1957 http://data.aad.gov.au/aadc/metadata/citation.cfm?entry_id=ASAC_2122-4 |
| Summary: | Acoustic data collection: Weddell seal female calls were recorded from four breeding sites, Weddell Arm (WA), Partizan Island (PI), Long Fjord (LF), and Topografov Island (TI), near Davis Station, Antarctica in November 1997. Routine recordings were made between noon and midnight in good weather conditions (ie, with low wind and no precipitation). Data collection was opportunistic in nature, with actively vocalising seals recorded for longer periods. Seals were approached from a frontal position, while they were hauled out on the ice or swimming in a pool, so that they were not surprised by the sudden arrival of the single researcher. The microphone was shielded from direct wind by the researcher's body, where possible, and brought within 3 m of the seal's head. The researcher indicated verbally whether the focal mother, her pup or a distant seal produced the call recorded. Jaw snaps were directed towards the researcher only, while mother-pup 'contact' calls were produced when the female was orientated towards the pup or the researcher. Recordings were terminated if the seals became aggressive or began to move away from the researcher. Potential disturbance to the animals was minimised by approaching the colonies only once a day for short periods of time, and only a few times throughout the study. Behavioural data collection Weddell seal mother-pup reunion behaviour was video recorded from three breeding sites; Turtle Rock, North Hutton Cliffs and South Hutton Cliffs, near McMurdo Sound, Antarctica from October-December 2003. Recordings were made between 08:00-22:00 in good weather conditions (ie, with low to moderate wind and no precipitation). Seals in McMurdo Sound are all habituated to close approach by research scientists as all pups are tagged within three days of birth, and all tags at breeding colonies are read every 3-5 days. The equipment box was positioned within 5 m of the focal mother-pup pair and left to record for 90 minutes. Recording Equimpment All Davis Station calls were recorded using a hand-held Sennheiser ME66 microphone (frequency response 0.05-20 kHz plus or minus 2.5 dB) fitted with an MZW 20 windscreen and a Sony DAT TCD-D7 tape recorder (frequency response 0.02-22 kHz plus or minus 1.0 dB). All McMurdo Station recording equipment was housed within an insulated box, containing heat packs, with only the video camera lens and microphone projecting externally. This equipment box was anchored to the ice with ice screws, when necessary, to prevent movement. Calls were recorded using a Sennheiser ME66 microphone (frequency response 0.05-20 kHz plus or minus 2.5 dB) fitted with a Rycote Softie windsock and a Sony TCD-D8 tape recorder (frequency response 0.02-20 kHz plus or minus 1 dB). Video footage was recorded using a Sony Digital8 DCRTRV355 Handycam with TDK P5-90HMPPEN Hi8 tapes. From the abstract of the attached paper: Vocal recognition may function as a critical factor in maintaining the phocid mother-pup bond during lactation. For vocal recognition to function, the caller must produce individually distinct calls that are recognised by their intended recipient. Mother-pup vocal recognition has been studied extensively in colonial otariids and appears to be characteristic of this family. Although less numerous, empirical studies of phocid species have revealed a range of recognition abilities. This study investigated whether Weddell seal (Leptonychotes weddellii) females produce individually distinct 'pup contact' calls that function during natural pair reunions. Fifteen calls from each of nine females recorded in the Vestfold Hills, Antarctica were analysed. One temporal, nine fundamental frequency and five spectral characteristics were measured. Results of the cross-validated Discriminant Function Analysis revealed that mothers produce individually distinct calls with 56% of calls assigned to the correct individual. The probability of achieving this level of discrimination on novel data by chance alone is highly improbable. Analysis of eight mother-pup reunions recorded near McMurdo Sound, Antarctica further demonstrated that these 'pup contact' calls function during natural pair reunions. Behavioural analysis also revealed that pups were chiefly responsible for establishing and maintaining close contact throughout the reunion process. Our study therefore demonstrates that Weddell seal females produce calls with sufficient stereotypy to allow pups to identify them during pair reunions, providing evidence of a functioning mother-pup vocal recognition system. Column A - Row 1: Gives the tag number of the female. - Rows 3-33: The list of acoustic measurements recorded from the spectrograms. - Rows 3-5: Temporal measurements recorded in milliseconds. - Rows 7-12: Frequency measurements recorded from the fundamental frequency. Rows 9-11 were measured at the 1/4, 2/4 and 3/4 temporal positions along the fundamental frequency respectively. - Rows 13-17: Give the number of the frequency band with the most energy at the temporal positions stated (i.e. fundamental frequency band=1, first harmonic=2 etc). - Rows 19-29: List the fundamental frequency measurements, taken at the temporal positions stated, used to calculate Mean frequency (Row 31) and the Coefficient of Frequency Modulation (Row 33) using the formula listed in the publication. - Rows 35 and 36: List the cursor error margins of the acoustic analysis program I used. Columns B-P - Give details of the above mentioned acoustic characteristics for 15 replicate calls from each of the 9 females sampled. |
|---|