Weddell seals do not lengthen calls in response to conspecific masking

• Other Authors: AADC (originator), AU/AADC > Australian Antarctic Data Centre, Australia (resourceProvider)
• Format: Dataset
• Language: unknown
• Published: Australian Ocean Data Network
• Subjects: biota; oceans; SEALS/SEA LIONS/WALRUSES; EARTH SCIENCE; BIOLOGICAL CLASSIFICATION; ANIMALS/VERTEBRATES; MAMMALS; CARNIVORES; Weddell Seal; Leptonychotes weddellii; vocalisation; HYDROPHONES; FIELD SURVEYS; AMD/AU; AMD; CEOS; GEOGRAPHIC REGION > POLAR; Weddell; Antarc*; Antarctica; Weddell Seals; walrus*
• Online Access: https://researchdata.ands.org.au/weddell-seals-lengthen-conspecific-masking/686097; https://data.aad.gov.au/metadata/records/ASAC_1132_pulse_repetition; http://data.aad.gov.au/aadc/portal/download_file.cfm?file_id=4580; http://data.aad.gov.au/aadc/portal/download_file.cfm?file_id=4579; https://data.aad.gov.au/aadc/metadata/citation.cfm?entry_id=ASAC_1132_pulse_repetition; https://secure3.aad.gov.au/proms/public/projects/report_project_public.cfm?project_no=AAS_1132

Some mammalian and avian species alter their vocal communication signals to reduce masking by background noises (including conspecific calls). A preliminary study suggested that Weddell seals (Leptonychotes weddellii) increase the durations of some underwater call types when overlapped by another calling seal. The present study examined the durations and overlapping sequences of Weddell seal calls recorded in Eastern Antarctica. The calling rate, call type (13 major categories), total duration, numbers of elements per call, and overlapping order of 100-200 consecutive calls per recording location were measured. In response to increased conspecific calling rates, the call durations and numbers of elements (within repeated-element call types) did not change or became shorter. Calls that were not overlapped were 3.8 plus or minus 6.1 s long, the first call in a series of overlapped calls was 14.4 plus or minus 15.7 s and subsequent calls in an overlapping series were 6.5 plus or minus 10.3 s. The mean durations of non-overlapped and overlapped calls matched random distributions. Weddell seals do not appear to be adjusting the durations or timing of their calls to purposefully avoid masking each others' calls. The longer a call is, the more likely it is to overlap another call by chance. An implication of this is that Weddell seals may not have the behavioural flexibility to reduce masking by altering the temporal aspects of their calls or calling behaviours as background noises (natural and from shipping) increase. The data were used in the two sets of analyses of Weddell seal underwater calls that are presented in Terhune, J.M. 2016. Weddell seals do not lengthen calls in response to conspecific masking. Bioacoustics 25: 75-88.