Adaptive beam-width control of echolocation sounds by CF–FM bats,<i>Rhinolophus ferrumequinum nippon</i>, during prey-capture flight

Matsuta, Naohiro; Hiryu, Shizuko; Fujioka, Emyo; Yamada, Yasufumi; Riquimaroux, Hiroshi; Watanabe, Yoshiaki

doi:10.1242/jeb.081398

Cited by 59 publications

(80 citation statements)

References 38 publications

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“…Previous studies have intensively examined spatial attention to a particular target (7)(8)(9)(10)(11)(12)(13)(14). However, in fact, predators usually capture successive prey items (e.g., aerial-feeding bats) (21).…”

Section: Discussionmentioning

confidence: 99%

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Echolocating bats use future-target information for optimal foraging

Fujioka

Aihara

Sumiya

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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When seeing or listening to an object, we aim our attention toward it. While capturing prey, many animal species focus their visual or acoustic attention toward the prey. However, for multiple prey items, the direction and timing of attention for effective foraging remain unknown. In this study, we adopted both experimental and mathematical methodology with microphone-array measurements and mathematical modeling analysis to quantify the attention of echolocating bats that were repeatedly capturing airborne insects in the field. Here we show that bats select rational flight paths to consecutively capture multiple prey items. Microphone-array measurements showed that bats direct their sonar attention not only to the immediate prey but also to the next prey. In addition, we found that a bat's attention in terms of its flight also aims toward the next prey even when approaching the immediate prey. Numerical simulations revealed a possibility that bats shift their flight attention to control suitable flight paths for consecutive capture. When a bat only aims its flight attention toward its immediate prey, it rarely succeeds in capturing the next prey. These findings indicate that bats gain increased benefit by distributing their attention among multiple targets and planning the future flight path based on additional information of the next prey. These experimental and mathematical studies allowed us to observe the process of decision making by bats during their natural flight dynamics.bat sonar | aerial capture | microphone array | mathematical modeling | flight dynamics S electively focusing attention on a particular target allows us to effectively extract information (1-4). Animals spatially focus their attention toward prey for suitable foraging (5, 6). During prey pursuit, most animals direct their visual attention toward it [e.g., tiger beetle (7), dragonfly (8), and falcon (9)]. Specifically, for example, dragonflies maintain a prey item at a constant retinal position during approaching it so that they steer an interception flight path (interception strategy) (10). However, for multiple prey items, the direction and timing of attention for effective foraging remain unknown.Echolocating bats actively emit sonar signals to obtain surrounding information and adaptively change the characteristics of the emissions depending on the situation (11). Therefore, their attention in terms of the sonar (sonar attention) is characterized as the direction to which bats emit their sonar beams (12-14). When echolocating bats approach an airborne insect, the sonar attention directs toward the prey (12, 13). During natural foraging, the sonar attention of bats alternately shifts from their flying direction to the side (15). Additionally the wild bats are capable of capturing two prey items within the short interval of 1 s (16).We predicted that bats localize multiple prey items by distributing their attention between them and then select an efficient flight path to successively capture the multiple prey. To test this prediction, ...

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Section: Discussionmentioning

confidence: 99%

“…Therefore, their attention in terms of the sonar (sonar attention) is characterized as the direction to which bats emit their sonar beams (12)(13)(14). When echolocating bats approach an airborne insect, the sonar attention directs toward the prey (12,13).…”

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confidence: 99%

Echolocating bats use future-target information for optimal foraging

Fujioka

Aihara

Sumiya

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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“…During the terminal subphase of a feeding buzz (often referred to as buzz II), species in the sister LDC bat families Vespertilionidae and Molossidae drop the peak frequency of their echolocation calls by an octave and, consequently, roughly double the breadth of their sonar beam Ratcliffe et al, 2013). HDC rhinolophids, through an unknown mechanism, also broaden their beam during the buzz (Matsuta et al, 2013). For all hawking species, we suggest that the buzz evolved to allow better tracking of ever more evasive prey (Elemans et al, 2011;Ratcliffe et al, 2013;Hulgard and Ratcliffe, 2016).…”

Section: Terminal Buzz Phases As Counter-measures Against Increasinglmentioning

confidence: 99%

Evolutionary escalation: the bat–moth arms race

Hofstede

Ratcliffe

2016

Journal of Experimental Biology

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Echolocation in bats and high-frequency hearing in their insect prey make bats and insects an ideal system for studying the sensory ecology and neuroethology of predator-prey interactions. Here, we review the evolutionary history of bats and eared insects, focusing on the insect order Lepidoptera, and consider the evidence for antipredator adaptations and predator counter-adaptations. Ears evolved in a remarkable number of body locations across insects, with the original selection pressure for ears differing between groups. Although cause and effect are difficult to determine, correlations between hearing and life history strategies in moths provide evidence for how these two variables influence each other. We consider life history variables such as size, sex, circadian and seasonal activity patterns, geographic range and the composition of sympatric bat communities. We also review hypotheses on the neural basis for antipredator behaviours (such as evasive flight and sound production) in moths. It is assumed that these prey adaptations would select for counter-adaptations in predatory bats. We suggest two levels of support for classifying bat traits as counter-adaptations: traits that allow bats to eat more eared prey than expected based on their availability in the environment provide a low level of support for counter-adaptations, whereas traits that have no other plausible explanation for their origination and maintenance than capturing defended prey constitute a high level of support. Specific predator counter-adaptations include calling at frequencies outside the sensitivity range of most eared prey, changing the pattern and frequency of echolocation calls during prey pursuit, and quiet, or 'stealth', echolocation.

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“…A sustained buzz I means maintaining higher peak frequency and broader pulse bandwidth compared with buzz II, which may give enhanced information for prey discrimination and localisation and the detection of tiny surface disturbances produced by the fish. In contrast, emitting a long buzz II entails broadening the acoustic field, which may be useful to anticipate the evasive movements of flying insects (Jakobsen and Surlykke, 2010;Matsuta et al, 2013). However, buzz II seems useless when fishing, as fish would in most cases simply vanish underwater, and bats would not obtain benefits from broadening their acoustic field.…”

Section: Echolocation Adjustmentsmentioning

confidence: 99%

Fine-tuned echolocation and capture-flight ofMyotis capacciniiwhen facing different sized insects and fish prey

Aizpurua

Aihartza

Alberdi

et al. 2014

Journal of Experimental Biology

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Formerly thought to be a strictly insectivorous trawling bat, recent studies have shown that Myotis capaccinii also preys on fish. To determine whether differences exist in bat flight behaviour, prey handling and echolocation characteristics when catching fish and insects of different size, we conducted a field experiment focused on the last stage of prey capture. We used synchronized video and ultrasound recordings to measure several flight and dip features as well as echolocation characteristics, focusing on terminal buzz phase I, characterized by a call rate exceeding 100 Hz, and buzz phase II, characterized by a drop in the fundamental well below 20 kHz and a repetition rate exceeding 150 Hz. When capturing insects, bats used both parts of the terminal phase to the same extent, and performed short and superficial drags on the water surface. In contrast, when preying on fish, buzz I was longer and buzz II shorter, and the bats made longer and deeper dips. These variations suggest that lengthening buzz I and shortening buzz II when fishing is beneficial, probably because buzz I gives better discrimination ability and the broader sonar beam provided by buzz II is useless when no evasive flight of the prey is expected. Additionally, bats continued emitting calls beyond the theoretical signal-overlap zone, suggesting that they might obtain information even when they have surpassed that threshold, at least initially. This study shows that M. capaccinii can regulate the temporal components of its feeding buzzes and modify prey capture technique according to the target.

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Adaptive beam-width control of echolocation sounds by CF–FM bats,Rhinolophus ferrumequinum nippon, during prey-capture flight

Cited by 59 publications

References 38 publications

Echolocating bats use future-target information for optimal foraging

Echolocating bats use future-target information for optimal foraging

Evolutionary escalation: the bat–moth arms race

Fine-tuned echolocation and capture-flight ofMyotis capacciniiwhen facing different sized insects and fish prey

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