Credit: CC0 Public Domain
Research has been conducted for decades to understand the songs of humpback whales. What is the reason they sing? Who and what is their intended audience? Scientists have found that whale songs are similar to bird songs. They are vocalizations used to attract mates or warn of potential rivals.
A University at Buffalo researcher has been telling a completely different story about whale song for several years. His most recent study, published in Animal Cognition, provides additional evidence that supports his argument to abandon whale songs being treated as an underwater analog of bird songs.
These findings show the changing nature of units in whale songs and how they change over time. These vocal changes show the inadequacy to use human labels like cries, moans, and chirps for a species that has the ability for more sophisticated sound production.
Eduardo Mercado Ph.D. is a professor of psychology at UB's College of Arts and Sciences. "The analyses in the paper suggest that it's not a good idea to think about whale songs in terms of language or musical notes." "The singing of the whales seems much more dynamic within songs than across years.
"Maybe it's just a matter switching from thinking of whale songs as musical notes, to something more freeform like dancing."
According to current hypotheses, whales create songs (songs), by combining sounds (units) with patterns (phrases). Mercado believes that single units can be compared to individual quills found in a peacock's tail. Each unit is functionally equivalent and only useful as a group.
According to Mercado's paper co-written with Christina E. Perazio (an assistant professor at University of New England), the units are functionally different. Unit morphing results in some units that are less detectable than other units. This finding challenges previous conclusions about fitness. Instead of songs revealing locations and movements, each song makes it easier to hear relevant units over long distances.
To illustrate his point, Mercado refers to George Orwell's revision to the barnyard moral codes in George Orwell’s "Animal Farm" in his title. He suggests that some humpback units are "more equal than others."
Mercado says that there are obvious differences between the units when you listen to different years' whale songs. They are so different it is like switching between musical genres. The whales use a different set of sounds every year.
What's the deal? What's the deal?
According to Mercado, it is unlikely.
Mercado used a method to collect detailed measurements of the variations in unit production by singers, and then compare those measures with characteristics produced in different years. This method emphasized vocal variability rather than summaries or "unit types".
"These changes are what got my interest in whale songs," says Mercado. "I wanted to know how they do it. How can other whales make sense of these changes if they are changing their sounds? Imagine someone with no training changing languages multiple times in a 10-year period and everyone still understanding everyone else, despite the differences.
These changes are evolutionary and not random. These modifications follow a set of rules. For example, pitch ranges are maintained even though the sounds may seem subjectively to vary quite a bit. These units may be morphed to improve the overall function of songs. This could help increase the number of locations from which listening whales are able to reliably locate, track and identify them.
This flexibility also reveals the limitations of computational or subjective methods of sorting units into discrete groups that fail to capture vocalizations.
Mercado says that these labels are a bad idea. "Shifts of pitch or duration could lead to an incorrect re-categorizing of units. Although we might believe that the whale is saying something new, it could be true.
Mercado says, "Humans don't have the best standard for distinguishing sounds. We must acknowledge that and respect it when we conduct research."
More information: Eduardo Mercado et.al, All units in humpback song are equal, but some are greater than others, Animal Cognition (2021). Information from Animal Cognition Eduardo Mercado et. al. All units in humpback song are equal, but some are greater than others. (2021). DOI: 10.1007/s10071-021-01539-8
