This post was contributed by Dustin Brewer, author of a recent paper in The Wilson Journal of Ornithology about the vocalizations of Blue Jays.
Almost everyone who lives in or near the eastern half of the U.S. is familiar with Blue Jays. This species, with its striking blue and white plumage, often lives in close proximity to people and regularly visits bird feeders. In fact, many people are so familiar with Blue Jays that they have formed strong opinions about them, which they freely share. People often emphatically tell me that they don’t like Blue Jays because of how noisy or bossy they are. Some, though—these people I know I’ll get along with—wistfully smile and tell me that they love Blue Jays. And that Blue Jays “love peanuts.” You’ll soon see why I wish that people had told me that prior to my master’s project.
I first began paying close attention to birds when I was hired to do “point count” surveys in southern Indiana, which entailed going to points and recording all bird species that I heard or (occasionally) saw. Doing these surveys helped me to become interested in the sounds that birds make. Around the same time that I was first hearing many Blue Jay call types, I learned that Blue Jays are also exceptionally gifted at solving problems, like other species in the crow family. I thought it would be fascinating to study a species with advanced mental capability that has a lot to say.
Fresh from a point count job in 2014, I went to Eastern Kentucky University to begin work toward a master’s degree. Another student in my lab, Julie Dahl, was already studying Blue Jays, which further inspired me to do the same. I found that although previous, very interesting studies had examined the entire repertoire of Blue Jay vocalizations, they were theses and dissertations that hadn’t been published. My goal was to complete a similar study, but to see it through to publication in a scientific journal. I still clearly remember how after I suggested to Gary Ritchison, my advisor, that my thesis focus on describing the vocal repertoire of Blue Jays, he swiveled in his chair, looked out his office window, nodded his head, and said, “That could work.” So I left his office and began following Blue Jays around campus and nearby areas with a recorder and a microphone in hand to figure out what they had to say. Escaping to the field to spend time with Blue Jays and record their calls soon became something I very much looked forward to and was a great way to learn how to observe interactions of nature’s parts.
My goal was to record as many Blue Jay vocalizations as possible, so that I could describe the full variety of distinct call types that this species uses. I also wanted to determine how Blue Jays use their repertoire of call types in different contexts. To accomplish these goals, I recognized that it would be helpful to mark individuals so that I could learn how repertoires between individuals vary. Though I was finally able to capture several birds after learning about their affinity for peanuts, I eventually conceded that I would have to settle for identifying different Blue Jay groups rather than individuals for purposes of analysis. I’d like to think that if I were to conduct another Blue Jay study, I’d have better luck catching individuals. However, I’ve come to learn not to underestimate the ability of Blue Jays to outsmart me.
I have also learned that Blue Jay vocalizations are almost as hard to put into “boxes” as are Blue Jays themselves. In addition to imitating other species, Blue Jays often blend different call types together to create intermediate forms. Spending many hours with Blue Jays in the field exposed me to many of these forms and made me realize that I’d need to create a nuanced, adaptable system if I wished to effectively categorize the vocalizations of Blue Jays. By the end of my field work, I had generated nearly 50 hours of recordings, which contained over 7,000 instances of Blue Jay vocalizations that I would use for accomplishing my task of creating a naming system that could assign Blue Jay calls to particular types. I relied on spectrograms, which create an image of sound, to describe the vocal repertoire of Blue Jays.
Ultimately, I settled on a system using well-defined terms that describe how calls look on spectrograms to create a name for each call type. For example, the “harsh descending jay” call type has a noisy quality that all “jay” calls share (stacks of bands; see image above), proceeds from a higher to lower frequency (“descending”), and has a “harsh” quality to it, which a rapid increase in frequency at the beginning of the call helps to create. I think of the last term in each call type name as a “class” that can be used to begin the categorization process or simply define a call more broadly. Using this system, I identified 36 distinct Blue Jay call types, which is quite a lot for a single bird species. Then, I used a quantitative approach to evaluate my system for naming Blue Jay call types. Specifically, I confirmed that inputting measures of calls (like duration, high frequency, frequency with the most energy, etc.) into an algorithm tended to assign calls to groups similarly to how my naming system does. This suggests that my system could be useful to others.
There is a lot more to learn about Blue Jay vocalizations. In the article that I published in The Wilson Journal of Ornithology, I reported the vocal repertoire of Blue Jays based on my naming system as well as the number of times that I recorded each call type. The “harsh descending jay” call type was the most common, which may indicate that it is especially important to Blue Jays. However, I did not relate call types to particular contexts in the published study. For example, I didn’t report which call type or class was most associated with long distance communication or with any other context. Some call-context associations were clear, but many call types were used in a variety of contexts. I look forward to revisiting the dataset from my master’s thesis to try to figure out how Blue Jays use their call types, and I am interested in connecting with others who also want to learn more about the functions of Blue Jays calls.
There is one Blue Jay call-context experience that I can still fondly recall, after over seven years, which illustrates how studying the functions of Blue Jay calls can be both surprising and enthralling. It was mid-May and I was at the edge of a green space at the center of Eastern Kentucky University’s campus. I was near a Blue Jay nest that I had been monitoring, and I knew that unless a predator had gotten lucky, fledglings would be emerging soon, if they hadn’t already. As usual, I had my recording equipment with me. When I approached the nest, I saw that it was empty. Below it, I was happy to see at least one fledgling Blue Jay directing what appeared to be a suspicious look at me. The parents of the fledgling were understandably not happy to see me. They took turns flying at me, seemingly trying to distract me. And then one of them perched on the brick wall in front of me and uttered what sounded like a perfect imitation of an American Crow (listen here), a species that could certainly be a danger to Blue Jay fledglings/nestlings. The call type was uttered numerous times, perhaps by both parents. Eventually, after recording many calls, I left them to get back to their jay—I mean, day.
Were the Blue Jays using the imitated call because I, like an American Crow, seemed to pose danger to their fledgling(s)? Could my observation be a part of a larger, meaningful pattern, given that I’ve documented other Blue Jay pairs uttering imitated hawk calls as I approached their nest? I don’t know yet, but I hope that my description of what Blue Jays say can advance our understanding of why they say what they do.