Rival Statistical Frameworks Reshape How Scientists Read Elephant Vocal Turn-Taking

When a herd of African savanna elephants is split into two subgroups roughly 200 metres apart, out of each other’s sight, the animals begin to rumble. These low-frequency calls, lasting on average around five seconds, are the glue of elephant social life, used to maintain contact, coordinate movement and manage reunions. But a new study suggests that whether scientists see those rumbles as evidence of genuine call-and-response conversation, or merely as a burst of excited group calling, may depend less on the elephants themselves and more on the statistical lens through which their vocal timing is analysed.

The research, published in Frontiers in Mammal Science, was carried out by Julia Joukhadar, Anton Baotic and Angela S. Stoeger of the Acoustics Research Institute at the Austrian Academy of Sciences and the University of Vienna. Their team recorded a semi-free-ranging herd of seven African savanna elephants (Loxodonta africana) at the Adventures with Elephants conservation and research unit in Bela Bela, South Africa, between 4 and 28 November 2018. Across 18 daytime recording sessions, handlers divided the herd into two subgroups positioned about 200 metres apart with no line of sight between them, a standardized separation designed to elicit frequent contact rumbles while minimizing visual cues. Synchronized microphones and video cameras captured every rumble, yielding 459 annotated calls from three adult females, two adult males and two calves.

The central question was deceptively simple: does the same set of elephant rumbles look like coordinated communication no matter how you measure it? To find out, the researchers applied three previously published analytical frameworks to the identical dataset. The first, a quartile-based approach, sorts calls into overlapping, adjacent, intermittent or single categories using statistical boundaries derived from the latencies between vocalizations. The second, bout criterion interval analysis, uses log-survivorship curves to find the natural breakpoint separating calls clustered within a bout from those separated by longer silences. The third, antiphonal probability analysis, adapted from a 1977 study of white-throated sparrows, asks whether an individual produces more calls after another’s vocalization than would be expected by chance alone.

The results were strikingly divergent. Under the quartile-based method, nearly half of all rumbles — 49 percent — were classified as overlapping, meaning they began before the previous call had ended. Adjacent calls, the category most likely to represent potential antiphonal responses, were the rarest at just 14 percent. The temporal boundaries themselves shifted compared with earlier work: the upper limit for intermittent calls came out at 71 seconds, well below the 120 seconds reported in a foundational 2003 study. Because the boundaries are computed from the data’s own quartiles, a dataset rich in overlapping calls compresses the thresholds, so the same framework can carve the same behaviour into different categories depending on how aroused or urgent the animals happen to be.

The antiphonal probability analysis told a different story again. Using a 25-second response window, the team tested whether each elephant answered others more often than chance would predict. Only two of the seven individuals — the adult male Chova and the adult female Messina — produced significantly more responses than expected. The remaining five, including Shan, the herd’s most prolific caller with 115 rumbles, showed no statistically reliable evidence of turn-taking. The authors caution that this framework is inherently conservative: it assumes that answerable time windows do not overlap, which inflates the number of responses expected by chance during periods of intense calling and biases the analysis against detecting genuine antiphony. Calls from unidentified individuals, which made up 19 percent of the dataset, further complicated individual-level conclusions.

The bout criterion interval analysis produced yet another picture. A Kolmogorov–Smirnov test confirmed that the intervals between calls deviated significantly from the random, exponential pattern expected if calling were uncoordinated. A segmented regression on the log-survivorship curve identified a breakpoint at roughly 124 seconds — dramatically longer than the 1.5-second threshold reported for wild elephant family groups departing a water hole in a 2012 study. By this measure, nearly 90 percent of all recorded rumbles fell within extended group-level calling bouts, suggesting that elephant vocal activity in this context is dominated by sustained chorusing rather than neat, alternating exchanges.

Notably, the 124-second bout criterion and the 71-second quartile boundary for intermittent calls, though derived by entirely different methods, point to a similar transition zone between clustered and isolated vocal activity. The authors are careful to note that this agreement does not constitute independent validation, but it hints that some underlying temporal structure may be real even as the labels attached to it vary. Call duration, meanwhile, told its own story: rumbles ranged from just over one second to 12.44 seconds, but duration differed little across temporal categories. Instead, mixed-effects models revealed that individual identity — not timing — was the strongest driver of how long a rumble lasted, with individual identity explaining considerably more variance than recording session.

The broader implication is unsettling for the field. Terms such as chorusing, turn-taking, duetting, bouts and antiphonal calling are often used interchangeably in elephant research and across taxa, even though they capture partially overlapping aspects of vocal coordination. The 30-second response window introduced in 2003 was adopted by later studies without further testing, and the new results show that such fixed thresholds may not generalize across datasets. Because only a handful of studies have examined elephant vocal timing at all, early methodological choices risk having a disproportionate influence on how temporal coordination is defined and detected — potentially shaping the entire field’s understanding of coordinated vocal behaviour in one of Earth’s most socially complex species.

The authors argue that the way forward lies not in crowning a single universal method, but in combining complementary frameworks. Mixture models, successfully used to estimate bout criteria in humpback whale social calls, could test whether inter-call intervals form distinct temporal populations. Permutation procedures could assess whether observed response timing differs from chance expectations, while mixed-effects and hierarchical models could account for individual identity, dyadic relationships, recording session and context simultaneously. Social bonds matter here: previous work has shown that chimpanzees preferentially join the choruses of closely bonded males, and that bonobo turn-taking tracks relationship strength, so dyadic analyses may reveal patterns that group-level statistics obscure.

For now, the elephants of Bela Bela continue to rumble across their 300-hectare range, indifferent to the statistical debates their calls provoke. But the study’s message resonates far beyond one herd: when scientists ask whether animals converse, the answer may depend as much on the mathematics of the question as on the biology of the animals. In a field where a single threshold, borrowed and never revalidated, can determine whether a rumble counts as a reply or mere noise, methodological humility may be the most important instrument in the bioacoustician’s kit.

Subject of Research: Temporal coordination and antiphonal calling in African savanna elephant vocalizations

Article Title: Methodological frameworks influence the classification and interpretation of temporal coordination in African savanna elephant vocalizations

Article References: Joukhadar, J., Baotic, A., & Stoeger, A. S. (2026). Methodological frameworks influence the classification and interpretation of temporal coordination in African savanna elephant vocalizations. Frontiers in Mammal Science, 5, Article 1893031. https://doi.org/10.3389/fmamm.2026.1893031

Image Credits: AI Generated

DOI: 10.3389/fmamm.2026.1893031

Keywords: African savanna elephant, acoustic communication, antiphonal calling, vocal timing, bioacoustics, temporal coordination, turn-taking, vocal bouts, rumbles, methodology, animal behavior, Loxodonta africana