Visual marking in mammals first proved by manipulations of brown bear tree debarking

Vincenzo Penteriani,Juan Diaz García,Ana Morales-González,David Cañedo,Héctor Ruiz-Villar,Chiara Bettega,Giulia Bombieri,Enrique González-Bernardo,Andrés Ordiz,Alfonso Hartasánchez,María Del Mar Delgado

doi:10.1038/s41598-021-88472-5

Abstract

The rather limited human ability to understand animal vision and visual signalling has frequently clouded our expectations concerning the visual abilities of other animals. But there are multiple reasons to suspect that visual signalling is more widely employed by animals than previously thought. Because visibility of visual marks depends on the background in which they are seen, species spending most of their time living in dark conditions (e.g., in forests and/or having crepuscular and nocturnal habits) may rely on bright signals to enhance visual display. Here, as a result of experimental manipulations, we present, for the first time ever, evidence supporting the use of a new channel of intraspecific communication by a mammal species, i.e., brown bear Ursus arctos adult males relying on visual marks during mating. Bear reactions to our manipulation suggest that visual signalling could represent a widely overlooked mechanism in mammal communication, which may be more broadly employed than was previously thought.

Highlights

Which bears signal, whereas visual communication has always been considered limited to different forms of body postures or behavioural displays
The debarking behaviour of brown bears Ursus arctos, which leaves bright and conspicuous marks on tree trunks, presents a unique yet unexplored opportunity to investigate new ways of visual communication in terrestrial mammals, and to better understand both bear and carnivore communication broadly. The hypothesis behind this experimental work is that brown bears may rely on visual communication via the conspicuous marks that they produce on trees
After manipulating bear tree marks in the Cantabrian Mountains, we found that bears removed the bark strips that we used to cover their marks during the mating season (Extended Data Figs. 3 and 4), suggesting that bear debarking may represent a visual communication channel used for intraspecific communication

Summary

Introduction

Which bears signal, whereas visual communication has always been considered limited to different forms of body postures or behavioural displays (but see[18]). After manipulating bear tree marks in the Cantabrian Mountains (north-western Spain), we found that bears removed the bark strips that we used to cover their marks during the mating season

Results

Conclusion