Night-time soundscape of midshipman fish during the breeding season. Night-time soundscape of midshipman fish during the breeding season. Shown here is a continuous record of close to 6 h of sound recording from a single hydrophone during one night of the summer breeding season with the readily apparent background, multi-harmonic stack of type I male hums (A). Selected segments of this recording show grunt and growl signaling originating from the focal nest where the hydrophone was positioned (B,C). Eileen L. McIver et al. J Exp Biol 2014;217:2377-2389 © 2014. Published by The Company of Biologists Ltd