01832nas a2200133 4500008004100000245009400041210006900135520134400204100002001548700003001568700002801598700001801626856005401644 2019 eng d00aDeep-diving pilot whales make cheap, but powerful, echolocation clicks with 50 µL of air0 aDeepdiving pilot whales make cheap but powerful echolocation cli3 a

Echolocating toothed whales produce powerful clicks pneumatically to detect prey in the deep sea where this long-range sensory channel makes them formidable top predators. However, air supplies for sound production compress with depth following Boyle’s law suggesting that deep-diving whales must use very small air volumes per echolocation click to facilitate continuous sensory flow in foraging dives. Here we test this hypothesis by analysing click-induced acoustic resonances in the nasal air sacs, recorded by biologging tags. Using 27000 clicks from 102 dives of 23 tagged pilot whales (Globicephala macrorhynchus), we show that click production requires only 50 µL of air/click at 500 m depth increasing gradually to 100 µL at 1000 m. With such small air volumes, the metabolic cost of sound production is on the order of 40 J per dive which is a negligible fraction of the field metabolic rate. Nonetheless, whales must make frequent pauses in echolocation to recycle air between nasal sacs. Thus, frugal use of air and periodic recycling of very limited air volumes enable pilot whales, and likely other toothed whales, to echolocate cheaply and almost continuously throughout foraging dives, providing them with a strong sensory advantage in diverse aquatic habitats.

1 aFoskolos, Ilias1 ade Soto, Natacha, Aguilar1 aMadsen, Peter, Teglberg1 aJohnson, Mark uhttp://www.nature.com/articles/s41598-019-51619-602346nas a2200313 4500008004100000245010600041210006900147260001600216520139500232653001901627653001701646653001901663653002101682653001501703653001301718653001701731653002201748653002101770653002701791100002101818700001801839700002301857700002001880700002001900700002101920700002001941700002201961856004901983 2018 eng d00aA 2.6-gram sound and movement tag for studying the acoustic scene and kinematics of echolocating bats0 a26gram sound and movement tag for studying the acoustic scene an cApr-10-20193 a

1.To study sensorimotor behaviour in wild animals, it is necessary to synchronously record the sensory inputs available to the animal, and its movements. To do this, we have developed a biologging device that can record the primary sensory information and the associated movements during foraging and navigating in echolocating bats.

2.This 2.6 ‐gram tag records the sonar calls and echoes from an ultrasonic microphone, while simultaneously sampling fine‐scale movement in three dimensions from wideband accelerometers and magnetometers. In this study, we tested the tag on an European noctula (Nyctalus noctula) during target approaches and on four big brown bats (Eptesicus fuscus) during prey interception in a flight room.

3.We show that the tag records both the outgoing calls and echoes returning from objects at biologically relevant distances. Inertial sensor data enables the detection of behavioural events such as flying, turning, and resting. In addition, individual wing‐beats can be tracked and synchronized to the bat's sound emissions to study the coordination of different motor events.

4.By recording the primary acoustic flow of bats concomitant with associated behaviours on a very fine time‐scale, this type of biologging method will foster a deeper understanding of how sensory inputs guide feeding behaviours in the wild.

10aAccelerometers10aarchival tag10aauditory scene10abat echolocation10abiologging10aechogram10aechoic scene10aflight kinematics10ainertial sensors10asensory-motor response1 aStidsholt, Laura1 aJohnson, Mark1 aBeedholm, Kristian1 aJakobsen, Lasse1 aKugler, Kathrin1 aBrinkløv, Signe1 aSalles, Angeles1 aMoss, Cynthia, F. uhttp://doi.wiley.com/10.1111/2041-210X.13108