Male sperm whale ( Physeter macrocephalus ) acoustics in a high-latitude habitat: implications for echolocation and communication

Abstract

Sperm whales (Physeter macrocephalus) are deep-diving predators foraging in meso-and bathypelagic ecosystems off the continental shelves. To investigate the ecophysiological and communicative function of various click types from male sperm whales in a high-latitude habitat, we deployed a large-aperture array of calibrated hydrophones off northern Norway (N69, E15). Data show that sperm whales in this habitat produce three click types: usual clicks, creak clicks and, occasionally, slow clicks. Usual clicks and creak clicks exhibit short duration, profound directionality and a frequency content suited for echolocation on meso-and bathypelagic fish and squids. The acoustic properties and low repetition rate of usual clicks are suited for long-range echolocation, whereas creak clicks have properties equivalent to signals in buzzes, the terminating pulse trains known from echolocating bats during prey capture. From these source parameters and the high acoustic activity during foraging dives, it is concluded that echolocation is an important sensory cue in prey location. Sound pressure levels of creak clicks and usual clicks measured off the acoustic axis suggest that sperm whales may be subjected to eavesdropping by conspecifics, thereby conveying information about food aggregations at estimated ranges of 6 km for creak clicks and 16 km for usual clicks. Slow clicks exhibit low directionality, low-frequency emphasis and a reduced repetition rate, suggesting that this click type is more suited for communication than for echolocation. Slow clicks can be detected by submerged conspecifics at ranges up to 60 km. Thus, sperm whales producing slow clicks may represent an odontocete species that utilizes long-range sound communication.

Spatial and seasonal patterns in acoustic detections of sperm whales Physeter macrocephalus along the continental slope in the western North Atlantic Ocean

“…Sperm whale distributions are typically patchy, and although the patterns we observed are largely consistent with expected latitudinal trends, they likely reflect characteristics of the individual recording sites as well as broader trends. An approximate detection range of 16 km has been estimated for sperm whale regular clicks at depth (Madsen et al 2002b), so each of our recording sites should be considered an individual point sample. Detection range may vary due to sound propagation conditions, ambient noise levels, and click characteristics, including source level, directionality, and orientation of the animal relative to the receiver.…”

Seasonal Trends in Acoustic Detection of Marine Mammals in Baffin Bay and Melville Bay, Northwest Greenland + Supplementary Appendix 1 (See Article Tools)

“…On leaving their female relatives, which almost always inhabit waters deeper than 1000 m at latitudes of less than 40˚, the males gradually move to higher latitudes: the larger and older the male, the higher the average latitude (Whitehead, 2002). Sperm whales have been reported to inhabit northern waters such as the Gulf of Alaska (Mellinger et al, 2004) and the Norwegian Sea (Christensen et al, 1992;Madsen et al, 2002) during summer. In the present acoustic dataset, sperm whales were detected in August and September 2012 and from September to November 2013, before sea ice had covered stations BB6 and BB10.…”

Male sperm whale (Physeter macrocephalus) coda production and coda-type usage depend on the presence of conspecifics and the behavioural context

“…Male and female sperm whales (Physeter macrocephalus L., 1758 (= Physeter catodon L., 1758)) emit sharp, impulsive clicks with a variety of repetition rates, especially during their deep, foraging dives (Weilgart 1990;Jaquet et al 2001;Madsen et al 2002b). The presence of stereotyped ''sequences of clicks which are repeated several times'' among sperm whale vocalizations was first noted by Backus and Schevill (1966).…”