October 20, 2022
Keio University
It has become clear that crows have complex societies, where they individually recognize their companions and build various relationships, including tense dominance hierarchies (strong vs. weak) and affiliative bonds involving mutual preening. In many animals, including humans, communication with individuals in tense or affiliative relationships is known to involve not only brain activity but also physiological responses, such as changes in heart rate, indicating an interaction between the brain and the body. However, the role of these physiological functions during communication in birds was not yet understood.
Kazuo Takeda and Nana Takahashi, graduate students at the Graduate School of Human Relations at Keio University, along with Professor Eiichi Izawa of the university's Faculty of Letters and their colleagues, established a removable wireless electrocardiogram (ECG) recording technology. In a laboratory setting, they recorded and analyzed the ECGs of two large-billed crows in a dominance relationship while they were facing each other, unrestrained and freely moving. The results revealed that (1) the subordinate (weaker) male, when facing the dominant male, experienced a decrease in heart rate and activation of the parasympathetic nervous system, while (2) the dominant male's heart rate remained unchanged, but its sympathetic nervous system was activated.
This discovery is the world's first to demonstrate that in social communication contexts, birds have also evolved mechanisms for physiological responses that correspond to their relationship with the other individual.
The results of this research were published in the online edition of "Royal Society Open Science" on October 19, 2022 (UK time).
Please see below for the full press release.