Structure and possible function of vocalizations of captive red-legged seriemas (Cariama cristata)

Very little is known about red-legged seriema (Cariama cristata) vocalizations and behavior. The focus of my research was to analyze the structure of red-legged seriema primary calls and to begin to test hypotheses related to their function. Captive red-legged seriema behavior, both vocal and non-vocal, was recorded at 7 institutions located in the United States from May 2007 through November 2008. To test whether calls serve a predator alarm function, seriemas were presented with a large stuffed dog, representing a predator stimulus, and 2 control stimuli, a large, stuffed penguin and a large, flowering potted plant. Baseline recordings with no manipulations were also made throughout the day, during the course of the study. All recordings of seriema vocalizations were assessed using sound analysis software to generate sound spectrograms for comparison. I identified three different note types within the seriema primary call: upsweep notes (U), ladder notes (L), and two-part notes (T). Each call begins with a set of U notes that increase in rate and lead into the main part of the call, which is made of L and T notes. Each note type was assessed for duration, frequency, energy, and entropy measurements. These measurements were reduced using factor analysis into two relevant factors. There were substantial differences across individuals for note type acoustic structure. Group differences in note types, including sex, location, and age, were not found. When presented with the dog model, vocal responses were given by only 3 individuals. Overall, it may be possible to identify individual seriemas by analyzing the structure of their primary call, which may allow researchers to identify individuals without physical markers.