It’s been some time in the making, but after months in the rain, and hours in the cold (not to mention a roller coaster of a relationship with statistics, which I’m pleased to report ended in a happy marriage) a few of our humpback whale research projects can be marked complete.
Last week we published two short manuscripts on the calling behavior of Southeast Alaskan humpback whales. Note that I said “calling-behavior”… not “social calling behavior” or “non-song calling behavior.” Now why might that be?
While the field of marine bioacoustics is vast, the number of people who have research programs dedicated to humpback whale vocalizations that aren’t song is relatively small (growing, but small). The first publication came out in the 1980’s by Dr. Greg Silber, who recorded a suite of vocalizations in groups of competitive male humpbacks on breeding grounds. Thus the term “social call” was born.
The running definition of a social call, however, has always been “a vocalizations produced independently of the structure of song”. Bearing this in mind several researchers, including myself, adopted the term “non-song vocalization”, to more specifically describe the vocalizations.
Here’s the rub… as it turns out these independent vocalizations sometimes pop-up as song units (As Bec Dunlop and Mindy Rekdahl have taught us) and as we recently discovered these vocalizations definitely aren’t always social.
In one of our new publications we describe how humpback whales in Southeast Alaska produce feeding calls, even when they are foraging alone. This call, we propose, is a prey manipulation call, and doesn’t always occur in social situations. In our second publication we demonstrate that when humpbacks in Southeast Alaska produce vocalizations in Alaska, they are doing so quietly. Which may indicate that they are intentionally restricting their audience (think whispering into someone’s ear versus yelling across the room). So while these calls almost certainly facilitate interactions between individuals humpbacks, they aren’t as widely broadcast as say… song (if Alaskan whales whisper, Hawaiian whales scream).
So what do we call these sometimes-social-sometimes-NOT-social-usually-not-song-unit-vocalizations?
I think we should refer to them as calls.
The use of the term ‘calls’ to encompass any short vocal unit that doesn’t occur in a song structure is well established in the animal communication literature (birds, frogs, primates). The term covers all manner of sins, and can be qualified (alarm call, flight call) to increase the specificity.
So, without further ado, let me introduce this borrowed lexicon into the marine mammal literature with this publication:
Let’s increase the specificity just a bit with: