@article {57639,
	title = {Deep-diving pilot whales make cheap, but powerful, echolocation clicks with 50 {\textmu}L of air},
	year = {2019},
	abstract = {<p>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\&rsquo;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\&thinsp;\&micro;L of air/click at 500\&thinsp;m depth increasing gradually to 100\&thinsp;\&micro;L at 1000\&thinsp;m. With such small air volumes, the metabolic cost of sound production is on the order of 40\&thinsp;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.</p>
},
	doi = {10.1038/s41598-019-51619-6},
	url = {http://www.nature.com/articles/s41598-019-51619-6},
	author = {Foskolos, Ilias and Aguilar de Soto, Natacha and Peter Teglberg Madsen and Johnson, Mark}
}
@article {53545,
	title = {Low energy expenditure and resting behaviour of humpback whale mother-calf pairs highlights conservation importance of sheltered breeding areas},
	journal = {Scientific Reports},
	volume = {9},
	year = {2019},
	month = {Jan-12-2019},
	abstract = {<p>Understanding the behaviour of humpback whale mother-calf pairs and the acoustic environment on their breeding grounds is fundamental to assessing the biological and ecological requirements needed to ensure a successful migration and survival of calves. Therefore, on a breeding/resting ground, Exmouth Gulf, Western Australia, we used animal-borne DTAGs to quantify the fine-scale behaviour and energetic expenditure of humpback whale mothers and calves, while sound recorders measured the acoustic environment. We show that: (i) lactating humpback whales keep their energy expenditure low by devoting a significant amount of time to rest, and their use of energy, inferred from respiration rates, is ~half than that of adults on their foraging grounds; (ii) lactating females mainly rest while stationary at shallow depths within reach of the hull of commercial ships, thus increasing the potential for ship strike collisions; (iii) the soundscape is dominated by biological sources; and (iv) even moderate increases of noise from vessels will decrease the communication range of humpback whales. Planned commercial infrastructure in Exmouth Gulf will cause a substantial increase in shipping traffic with the risk of ship strikes and acoustic disturbance potentially compromising energy reserves for the southern migration of humpback whales.</p>
},
	doi = {10.1038/s41598-018-36870-7},
	url = {http://www.nature.com/articles/s41598-018-36870-7},
	author = {Bejder, L. and Videsen, S. and Hermannsen, L. and Simon, M. and Hanf, D. and Peter Teglberg Madsen}
}
