27/07/2026 - 7:11 GMT+2
Humans are not the only mammals capable of deceiving their own kind. That is the conclusion of a study focusing on Cantabrian brown bears, carried out with input from experts at the CSIC, the FAPAS, several Spanish and European universities and the Principality of Asturias.
The study published in the 'Journal of Mammalogy' (source in Spanish) argues that a minority of the bears living among the peaks of León, Asturias and Cantabria may be 'lying' about their true size to avoid having to face larger rivals. How? By using the signs and markings these mammals leave in their surroundings to stake out territory.
Seven males (4.3% of the 164 tracked) left marks at exaggerated heights by climbing or using tree trunks or other kinds of platforms to leave their mark higher than their real size would allow. Of these, 57.1% were adults and 42.9% subadults. "These results suggest that brown bears can manipulate index signals that were previously thought impossible to fake, which adds complexity to their communication system," the authors summarise.
To investigate this behaviour, the team monitored 14 marking sites in the Cantabrian Mountains over 117,552 hours of recording between 2021 and 2024. The results showed that these crafty seven males climbed trees to leave chemical and visual signals higher than their real height would allow.
