Dear colleagues, See below a link to a prepublished version of this paper, now in review in eLife, this version is freely available, https://www.biorxiv.org/content/early/2018/04/18/303743 This is the abstract: Animals aggregate to obtain a range of fitness benefits, but a common cost of aggregation is increased detection by predators. Here we show that, in contrast to visual and chemical signallers, aggregated acoustic signallers need not face higher predator encounter rate. This is the case for prey groups that synchronize vocal behaviour but have negligible signal time-overlap in their vocalizations. Beaked whales tagged with sound and movement loggers exemplify this scenario: they precisely synchronize group vocal and diving activity but produce non-overlapping short acoustic cues. They combine this with acoustic hiding when within reach of eavesdropping predators to effectively annul the cost of aggregation for predation risk from their main predator, the killer whale. We generalize this finding in a mathematical model that predicts the key parameters that social vocal prey, which are widespread across taxa and ecosystems, can use to mitigate detection by eavesdropping predators. Cheers, we hope you enjoy seeing the amazing coordinated behaviour of beaked whales! Natacha Natacha Aguilar de Soto, PhD Research Fellow BIOECOMAC (Marine Biodiversity, Ecology and Conservation) University of La Laguna Tenerife, Canary Islands, Spainnaguilar@ull.edu.es <naguilar@ull.es> / 922 318324-87 / 636876526 http://cetaceos.webs.ull.es/bioecomac/ Visiting Scholar Scottish Marine Institute. UUniversity of St Andrews. Scotland. UK https://creem2.st-andrews.ac.uk/person/na30/