Posts made in September 2023

Cetacean Vibrations: Sexual Bubble Stimulation in Humpback Whales

It’s no secret: animals have sex, just like we do.

Biologically, sexual reproduction is defined as a process by which two organisms of differing sexes combine genetic information to create new offspring. This shuffling of genetic information fosters genetic diversity, which allows species to better adapt to their changing environmental circumstances. If a gene is beneficial in an organism’s survival, then that organism is more likely to survive, reproduce and pass on the gene: the faster antelope is more likely to outrun the lion. The opposite is true for disadvantageous genes: the slowest antelope is more likely to be eaten by the lion.

But, in cetaceans, the story of sex doesn’t end with that stale, biological definition. In fact, that’s just the beginning.

Like humans, cetaceans not only have sex, but they experience sexual pleasure. A 2022 study published in Current Biology suggests that female bottlenose dolphins (Tursiops truncatus) possess anatomically functional clitorises that are important for mating and play behaviors. Female bottlenoses often stimulate each other’s clitorises in sexual interactions, and the position of the clitoris indicates that it is likely stimulated during male-female reproduction.

Unlike dolphins, no clitoris-type physiological structure has been found in humpback whales (Megaptera novaeangliae). Instead, female humpbacks have a genital slit accompanied by two mammary slits on either side, which are used for nursing calves. However, female humpbacks’ lack of clitoris does not equate to a lack of pleasure: a 2022 study published in Aquatic Mammals suggests that female humpbacks may purposely position their mammary glands and genital slit above bubbles blown by male humpbacks. This finding indicates that females may experience pleasure from bubble stimulation.

Bubble behaviors have been documented in most types of whales and provide a variety of different functions; bubbles are formed during stressful situations, in aggressive male-male competition, in play, in aversion tactics, and in foraging situations. However, bubbles used for sexual pleasure are a novel concept.

Primary investigator Meagan Jones and her co-authors at the Whale Trust documented this behavior during the breeding season between 2000 and 2003 in Au’au Channel in West Maui, Hawaii. Over the course of a fourteen-minute video, three males were observed producing bubbles directly under a female’s genitalia twelve separate times. Instead of fleeing, the female seems to accept these bubbles, exhibiting behaviors such as “rolling toward, arching, or slightly lifting and/or moving her tail above the bubble releases”.

Jones et al. propose two possible explanations for these novel behaviors. On one hand, the authors hypothesize that these bubbles could serve a pre-sexual purpose – in other words, foreplay. Alternatively, the authors propose that the observed female could have been in late pregnancy and the bubbles could stimulate the release of oxytocin, a hormone essential for giving birth. It is also interesting to note that in humans, oxytocin is also released during orgasms. At the end of the paper, Jones mentions potential research into the hormonal state of the female whale receiving this behavior. Understanding the female’s reproductive state (ie if she was in late pregnancy) would elucidate the context of the behavior.

Prior to this publication, no research has been published on the use of bubbles in male-female sexual interactions in humpback whales. However, this season at Cook Islands Whale Research, we have observed this behavior in humpbacks in the waters around Rarotonga and have captured it on camera: Following a group of one female and two male escorts for over two hours, we observed the primary male escort blowing bubbles under the genital slit of the female multiple times. She spent a large amount of surface time in a side-on position, seeming to receive the attentive behaviors of the males, which included bubble streams and bursts.

Though we clearly cannot yet draw conclusions from our observations without further data collection and analysis of these behaviors, Jones et al.’s profiling of this behavior provides an exciting new framework with which to analyze our data and potentially build on her hypotheses.

This line of research provides another interesting parallel between human and whale behaviors, demonstrating again why we connect with them so deeply and why they deserve our respect and protection.

Picture of male humpback (center frame) blowing bubbles under female (top left)


1 Brennan, P. L. R., Cowart, J.R., & Orbach, D. N. (2022). Evidence of a functional clitoris in dolphins. Current Biology, 32(1).

2 Bagemihl, B. (1999). Biological Exuberance: Animal Homosexuality and Natural Diversity (Macmillan).

3 Jones, M. E., Nicklin, C. P., & Darling, J. D. (2022). Female humpback whale (Megaptera novaeangliae) positions genital-mammary area to intercept bubbles emitted by males on the Hawaiian breeding grounds. Aquatic Mammals, 48(6), 617-620.

4 Moreno, K. R., & Macgregor, R. P. (2019). Bubble trails, bursts, rings, and more: A review of multiple bubble types produced by Cetaceans. Animal Behavior and Cognition, 6(2), 105-126

A Day in the Life of a Whale Biologist… sometimes never directly involves whales.

From left to right: Gloria, Ella, Francesca, & Gustowo

I hate to burst your bubble, but despite my previous blog posts in which I appealingly glorify my encounters with whales, I must admit that in my month of being in Rarotonga, I have only been out on the boat with the whales a handful of times. But this is not due to a lack of want or a lack of effort.

As a new research assistant, I entered this experience with a grossly idealized idea of what consisted of whale conservation work. In my head, I envisioned endless days on a beautiful blue expanse of open ocean, watching whales breach and play around me, while being surrounded by a group of beautiful, women scientists. I expected work in the form of long, tiresome days, raw sunburns, and data analysis. While some days are as I imagined, they consist of only half of the story.

The other fifty percent consists of a grind. Every day at Cook Islands Whale Research, the team (which is, in fact, a group of hot women scientists) and I are met with a series of simultaneously unexpected and colossal challenges that seem, at best, tangentially related to whales, and mostly consist of seemingly random tasks of manual labor. These undertakings range from fixing car belts to hauling blue whale vertebrae to renovating and decorating the Paradise Inn to be a whale education center to the morally uncomfortable duty of debt collection.

The Moral of the Story: Being a whale biologist requires being a jack of all trades.

And no one is more qualified for this job than Nan Hauser. Since her arrival on the island, Nan does not quit. Without fail, she seizes the day by attacking the projects at hand (which, to me, seem never-ending and excessively out-of-my-depth), no matter how massive, miniscule, or technical the operation. And her gung-ho, go-get-it, DIY attitude inspires all of us around her to work just as hard. Despite a to-do list that, like a persistent garden weed seems to grow longer and more convoluted each day, we consistently end the day exhausted and having accomplished a million things.

So far, I have acquired skills in: cooking, gardening, interior design, tire replacement, graciously pleading for funding, and power washing various types of surfaces. While these are not skills I expected to gain, they are ones that I have learned are just as important to whale biology as the scientific ones that accompany them. And these lessons have been paramount in my development as a research intern; whale biology is not smooth sailing (literally). Commitment to whale conservation requires you to be a mechanic, a renovator, a gardener, and a laborer.

I have always wondered why more people don’t pursue careers in cetacean conservation. It is undeniable that humans experience an exceptional connection to whales. Perhaps it is due to their intelligence, sociality, and altruistic nature that mirrors our own; maybe whales remind us of those qualities that reveal the best of our humanity, which so often become lost within ourselves. Or perhaps whales represent a promise that wild spaces can still exist. Whales were once viewed as economic jackpots and therefore hunted into near extinction to be made into soaps, oils, animal feed, and corsets. Now, due to massive conservation efforts, humanity’s conception of whales has morphed into that of an embodiment of pristine nature, and many populations have since recovered. Whales, now, represent an escape from our built landscape into the majesty of true, untouched Nature. They are a conservation success story.

But, the Fact of the Matter is: Whale conservation is really hard work.

No one recognizes the grunt work behind an operation like Cook Islands Whale Research. Its dirty, hands-on nature is so easily disguised behind a snowy idealization of whales, and once revealed, tends to deter people from the work. But, for the people I have the privilege of working with, every task, no matter how menial it seems, is completed without complaint and in the name of the whales. And this is the nature of a true conservationist.

The Most Important Lesson: If you want it, you must make it happen.

The Unsung Heroes Behind CIWR This Season So Far:

Nan Hauser

Katherine Waru


Julia Graeter

Gloria Harvey

Ella Ruland

Francesca Radford

Callie Cho

Nico Ransome

Disha Kabra

Travis Horton

Katherine and Callie

From left to right: Julia, Nan, Ella, Francesca, Callie, Gloria

New Study Examines the Effect of Vessel Noises on Humpback Whale Singers by Callie Cho


As anthropogenic noise continues to increase in our oceans, animals who employ acoustic communication have become increasingly challenged to make their sounds heard and understood by other members of their species. This artificial noise interferes with behaviors essential to individual and species survival, such as acts of courtship, displays of dominance, communication of resources, feeding behaviors, and navigation.

One animal whose form of communication has become increasingly encroached upon by anthropogenic noise is the humpback whale (Megaptera novaeangliae). While it is not completely known why male humpbacks sing, this behavior mainly occurs in breeding grounds and migratory corridors, indicating that it is important for comparing and communicating fitness to females and to other male singers. Understanding the effect of human-created noises such as boat sounds on humpback song is essential in advancing productive conservation initiatives.

Humpback whales naturally adapt their singing intensity in response to the given amount of naturally occurring noise in their environment; noises such as wind, water, and reef sounds. The unconscious act of adjusting vocal effort in the presence of other sounds is known as the Lombard effect and is present in many acoustically communicating animals. However, it is unknown if the Lombard effect is present in singing humpback males in relation to vessel noise.

A recent study conducted by Girola et al. (April 2023) at the University of Queensland sought to answer this question by studying eastern Australia’s singing males’ Lombard response to ambient wind noise as compared to wind noise accompanied by vessel noise. The scientists hypothesized that if the males’ Lombard effect accounted for vessel noise as well as wind noise, then their singing would change accordingly in the presence of a vessel as compared to when no vessel was present.

In September and October of 2010, Girola et al. recorded humpback song in Peregian Beach, a migratory corridor for humpbacks moving southbound towards Antarctica from breeding grounds in the Great Barrier Reef. The researchers employed the use of four stationary buoys to record singers within 5km of the designated study area, and they methodically drove a vessel along an established route. Recordings disturbed by the sounds of rain, other vessels, or loud fish choruses were excluded from the study to isolate the sounds of wind and the research vessel noises.

After extensive song unit analysis, the authors concluded that while humpback singers adjust their songs according to wind levels, they do not do so for vessel noises. In other words, the Lombard effect is present in response to varying levels of wind noise but not present in response to vessel noises. While this result suggests that other coping strategies could be at play, no other ones have been scientifically studied.

In conclusion, this study reinforces the importance of understanding the effect of anthropogenic noises on humpback whale behavior. Knowing that singers do not employ the Lombard effect when accounting for vessel noise opens doors for more studies to be done on alternate coping mechanisms. This result could also suggest that whales do not, in fact, have a fixed strategy in place to deal with this type of anthropogenic noise, considering their lack of song adjustment in response to vessel noise. If the latter is true, then anthropogenic noise could pose a detrimental problem for humpback whale vocalization and its associated behaviors.

Specifically in relation to our research, the waters around Rarotonga are part of the migratory corridor of the last population of endangered migrating humpback whales in the world. In these waters, humpbacks opportunistically breed and birth their young. Therefore, conservation initiatives in the Cook Islands should aim to control vessel noise in proximity to singing males. It is imperative to understand the effects of vessel noise to best protect these amazing animals.


1 Payne R, McVay S. 1971 Songs of Humpback whales. Science 173, 585-597. (doi: 10.1126/science.173.3997.585)

2 Dunlop RA, Cato DH, Noad MJ. 2014 Evidence of a Lombard Response in migrating humpback whales (Megaptera novaeangliae). J. Acoust. Soc. Am. 136, 430-437. (doi:10.1121/1.4883598)

3 Whitlock, J. (2012). Understanding the Lombard Effect. New Zealand Acoustics, 25(2), 14–17.

4 Girola E, Dunlop RA, Noad MJ. 2023 Singing humpback whales respond to wind noise, but not to vessel noise. Proc. R. Soc. B 290: 20230204.