12/17/2022 0 Comments Twitter rapidclick rapid![]() Alternatively, short bursts of high-repetition-rate clicks have been proposed to function in communication ( Aguilar Soto et al., 2011 S. ![]() Moreover, buzzes are routinely associated with increased maneuvering and/or changes in the body acceleration rate (‘jerk’) ( Johnson et al., 2004 Miller et al., 2004 Aguilar Soto et al., 2011), likely resulting from fast movements in pursuit of prey. When closing in on targets during buzzes, echolocating toothed whales consistently reduce the inter-click interval (ICI) and output levels of clicks ( Morozov et al., 1972 Au, 1993 Miller et al., 1995 Johnson et al., 2006 DeRuiter et al., 2009 Wisniewska et al., 2016). ![]() A buzz represents the terminal phase of the biosonar-based foraging process, which basically consists of echo-guided search, approach and capture phases ( Griffin, 1958). Rapid increases in the click rate at the end of echolocation click sequences have been interpreted as attempts to capture prey, coined ‘buzzes’ in several echolocating species of bats ( Griffin et al., 1960) and odontocetes ( Miller et al., 1995 Miller et al., 2004 Johnson et al., 2006). Neves, Acoustic behavior of Risso's dolphins, Grampus griseus, in the Canary Islands, Spain, PhD Thesis, University of St Andrews, St Andrews, 2012). The vocal repertoire of this species includes whistles, grunts, chirps, echolocation clicks (pulses), rapid series of clicks that have been described as barks, buzzes and isolated burst-pulses, and a combination of whistles and pulses, called whistle-burst pulses ( Kruse et al., 1999 Corkeron and Van Parijs, 2001 Madsen et al., 2004 S. Cuvier 1812) is a deep-diving social delphinid for which a diversity of vocalizations has been described, yet with little insight about functionality. This information, however, is essential to quantify foraging and social behavior and to assess potential impacts of disturbance from human activities. These problems in linking individual acoustic signals with function in these taxa have largely prevented the contextualization and functional discrimination of pulsed sounds, which may be used for either echolocation or communication. Many toothed whales have sophisticated communication systems, but study of their vocal behavior is hampered by problems in identifying which animal makes a sound and which animals respond to these calls. Our understanding of the echolocation behavior of toothed whales is gradually increasing ( Miller et al., 2004 Madsen et al., 2005 Wisniewska et al., 2016 Clausen et al., 2011), but is limited by the challenges of studying the acoustic behavior of free-ranging marine animals that often vocalize at depth and out of sight. They use sound to communicate and echolocate, emitting directional pulses of high-frequency sound and listening for echoes to build an acoustic scene of prey and landmarks using an active echolocation sense ( Madsen and Surlykke, 2013). Toothed whales (odontocetes) have evolved extraordinary capabilities to use sound as a main sensory cue ( Au, 1993 Tyack, 1999). In contrast, the shorter, isolated burst pulses that are generally emitted by the dolphins while at or near the surface are used outside of a direct, known foraging context. These results suggest that the longer, relatively lower amplitude, jerk-associated buzzes are used in this species to capture prey, mostly during the bottom phase of foraging dives, as seen in other odontocetes. Burst pulses consisted of relatively short click series averaging 45±54 clicks with decreasing repetition rate and longer inter-click interval that were less likely to be associated with regular echolocation and the jerk signal. They consisted of series averaging 359☒10 clicks (mean±s.d.) with an increasing repetition rate and relatively low amplitude. Buzzes followed regular echolocation clicks and coincided with a strong jerk signal from accelerometers on the tag. rapid change of acceleration) and temporal association with click trains. Two types of rapid click-series pulsed sounds, buzzes and burst pulses, were identified as produced by the tagged dolphins and classified using a Gaussian mixture model based on their duration, association with jerk (i.e. ![]() Archival tags were placed on free-ranging Grampus griseus to quantify and discriminate between pulsed sounds used for echolocation-based foraging and those used for communication. This capability to identify the function of sounds is important for understanding and interpreting behavior it is also essential for monitoring and mitigating potential disturbance from human activities. Early studies that categorized odontocete pulsed sounds had few means of discriminating signals used for biosonar-based foraging from those used for communication. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |