担当区分：筆頭著者   記述言語：英語   出版者・発行元：Proceedings of the Royal Society B Biological Sciences  

Encounters between competitive individuals or groups are common in social animals and can involve costly aggression; thus, animals often employ strategies to minimize direct conflict. However, research on whether and how animals adjust their group spatial structure when they encounter or spatially co-occur with a different group remains limited. We investigated how non-territorial units in feral horse multilevel societies manage spatial encounters with neighbouring units. We observed 25 reproductive units in northern Portugal, using drones, and employed statistical analyses to quantify spatial dynamics. We found that horses actively adjusted their spatial formations depending on the proximity of other units. Units became more circular and cohesive when other units approached, but when extremely close, they elongated their shapes to avoid boundary crossings. These adjustments indicate that horses maintain flexible unit boundaries to prevent mixing with other units. A notable exception was a particular pair of units that frequently crossed boundaries and intermixed, representing a unique social level within the horse multilevel society. Overall, our findings indicate that feral horses respond adaptively to inter-unit encounters by balancing the benefits of aggregation with the need to reduce direct overlap, providing new insights into the spatial organization of non-territorial societies.

DOI： 10.1098/rspb.2025.2468

Open Access

Web of Science

Scopus

PubMed

担当区分：筆頭著者   記述言語：英語   掲載種別：研究論文（学術雑誌）  

DOI： 10.1098/rsif.2025.0187

記述言語：英語   出版者・発行元：Animal Cognition  

One of the executive functions, inhibitory control, enables animals to suppress ineffective behaviors and facilitate flexible behavior. Seabirds, particularly those of the family Laridae, exploit diverse food resources across various environments. This suggests a possible link between their foraging behavior and inhibitory control. However, to date, inhibitory control in seabirds has not been assessed. We used a cylinder task to assess inhibitory control in wild black-tailed gulls, which are highly omnivorous seabirds. The task required gulls to suppress the dominant response of pecking at food inside a transparent cylinder, detour to the side openings, and retrieve the food without pecking the cylinder. The trial was considered successful if the gull retrieved the food without pecking the cylinder. Ten of the 12 individuals succeeded in the task within 10 trials, with their success rates improving across trials. These findings suggest that black-tailed gulls exhibit moderate levels of inhibitory control among birds and may learn detouring behavior through repetition.

DOI： 10.1007/s10071-025-01997-4

Open Access

Web of Science

Scopus

PubMed

記述言語：英語   出版者・発行元：Current Biology  

The decision to urinate involves a complex combination of both physiological and social considerations1,2,3. However, the social dimensions of urination remain largely unexplored. More specifically, aligning urination in time (i.e. synchrony) and the triggering of urination by observing similar behavior in others (i.e. social contagion) are thought to occur in humans across different cultures (Figure S1A), and possibly also in non-human animals. However, neither has been scientifically quantified in any species. Contagious urination, like other forms of behavioral and emotional state matching4, may have important implications in establishing and maintaining social cohesion, in addition to potential roles in preparation for collective departure5 (i.e. voiding before long-distance travel) and territorial scent-marking6 (i.e. coordination of chemosensory signals). Here, we report socially contagious urination in chimpanzees, one of our closest relatives, as measured through all-occurrence recording of 20 captive chimpanzees across >600 hours. Our results suggest that socially contagious urination may be an overlooked, and potentially widespread, facet of social behavior.

DOI： 10.1016/j.cub.2024.11.052

Web of Science

Scopus

PubMed

DOI： 10.1111/jzo.13100

開催年月日： 2026年3月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：東京  

開催年月日： 2026年3月

記述言語：日本語   会議種別：口頭発表（一般）  

開催年月日： 2026年1月

記述言語：英語   会議種別：口頭発表（一般）  

開催地：Tokyo   国名：日本国  

開催年月日： 2025年10月

記述言語：日本語   会議種別：口頭発表（一般）  

開催地：長崎  

開催年月日： 2025年10月

記述言語：日本語   会議種別：ポスター発表  

開催地：長崎