Brown bears manipulate signals to appear larger, study finds

An international team of scientists monitored 164 brown bears (Ursus arctos) across 14 marking sites in the Cantabrian Mountains between 2021 and 2024, collecting over 117,000 hours of camera‑trap footage. The analysis identified seven adult or juvenile males – about 4.3% of the observed bears – that placed visual and scent marks at heights greater than their natural reach, either by climbing or using platforms installed on trees and posts. This behaviour, described as a form of deceptive signaling, is the first documented case of such communication dishonesty in bears and suggests a more complex social signaling system than previously understood. The findings were published in the Journal of Mammalogy.

The researchers emphasized that while the behaviour is rare, it provides new insight into animal communication, indicating that some brown bears can intentionally exaggerate their size to deter rivals.