Wisniewska Danuta M.

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Wisniewska
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Danuta M.
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  • Article
    Sperm whale codas may encode individuality as well as clan identity
    (Acoustical Society of America, 2016-05-19) Oliveira, Claudia ; Wahlberg, Magnus ; Silva, Monica A. ; Johnson, Mark P. ; Antunes, Ricardo ; Wisniewska, Danuta M. ; Fais, Andrea ; Goncalves, Joao M. A. ; Madsen, Peter T.
    Sperm whales produce codas for communication that can be grouped into different types according to their temporal patterns. Codas have led researchers to propose that sperm whales belong to distinct cultural clans, but it is presently unclear if they also convey individual information. Coda clicks comprise a series of pulses and the delay between pulses is a function of organ size, and therefore body size, and so is one potential source of individual information. Another potential individual-specific parameter could be the inter-click intervals within codas. To test whether these parameters provide reliable individual cues, stereo-hydrophone acoustic tags (Dtags) were attached to five sperm whales of the Azores, recording a total of 802 codas. A discriminant function analysis was used to distinguish 288 5 Regular codas from four of the sperm whales and 183 3 Regular codas from two sperm whales. The results suggest that codas have consistent individual features in their inter-click intervals and inter-pulse intervals which may contribute to individual identification. Additionally, two whales produced different coda types in distinct foraging dive phases. Codas may therefore be used by sperm whales to convey information of identity as well as activity within a social group to a larger extent than previously assumed.
  • Preprint
    Narrow acoustic field of view drives frequency scaling in toothed whale biosonar
    ( 2018-10) Jensen, Frants H. ; Johnson, Mark P. ; Ladegaard, Michael ; Wisniewska, Danuta M. ; Madsen, Peter T.
    Toothed whales are apex predators varying in size from 40-kg porpoises to 50-ton sperm whales that all forage by emitting high-amplitude ultrasonic clicks and listening for weak returning echoes [1, 2]. The sensory field of view of these echolocating animals depends on the characteristics of the biosonar signals and the morphology of the sound generator, yet it is poorly understood how these biophysical relationships have shaped evolution of biosonar parameters as toothed whales adapted to different foraging niches. Here we test how biosonar output, frequency, and directivity vary with body size to understand the co-evolution of biosonar signals and sound-generating structures. We show that the radiated power increases twice as steeply with body mass (P ∝ M1.47±0.25) than expected from typical scaling laws of call intensity [3], indicating hyperallometric investment into sound production structures. This is likely driven by a strong selective pressure for long-range biosonar in larger oceanic or deep-diving species to search efficiently for patchy prey. We find that biosonar frequency scales inversely with body size (F∝ M-0.19±0.03), resulting in remarkably stable biosonar beamwidth that is independent of body size. We discuss how frequency scaling in toothed whales cannot be explained by the three main hypotheses for inverse scaling of frequency in animal communication [3-5]. We propose that a narrow acoustic field of view, analogous to the fovea of many visual predators, is the primary evolutionary driver of biosonar frequency in toothed whales, serving as a spatial filter to reduce clutter levels and facilitate long-range prey detection.
  • Article
    Low hunting costs in an expensive marine mammal predator
    (American Association for the Advancement of Science, 2024-05-15) Rojano-Donate, Laia ; Teilmann, Jonas ; Wisniewska, Danuta M. ; Jensen, Frants H. ; Siebert, Ursula ; McDonald, Birgitte I. ; Elmegaard, Siri L. ; Sveegaard, Signe ; Dietz, Rune ; Johnson, Mark ; Madsen, Peter T.
    Many large terrestrial mammalian predators use energy-intensive, high-risk, high-gain strategies to pursue large, high-quality prey. However, similar-sized marine mammal predators with even higher field metabolic rates (FMRs) consistently target prey three to six orders of magnitude smaller than themselves. Here, we address the question of how these active and expensive marine mammal predators can gain sufficient energy from consistently targeting small prey during breath-hold dives. Using harbor porpoises as model organisms, we show that hunting small aquatic prey is energetically cheap (<20% increase in FMR) for these marine predators, but it requires them to spend a large proportion (>60%) of time foraging. We conclude that this grazing foraging strategy on small prey is viable for marine mammal predators despite their high FMR because they can hunt near continuously at low marginal expense. Consequently, cessation of foraging due to human disturbance comes at a high cost, as porpoises must maintain their high thermoregulation costs with a reduced energy intake.