The Animal communication is a fascinating and extremely complex topic., since species can use multiple forms of communication to transmit different information to their congeners. Despite the fact that the study of animal communication has been and continues to be one of the most prolific fields of research, it still much remains to be discovered.
In the case of communication in species of terrestrial mammals, most of the research has focused on communication through chemical signals (faeces, urine and body glands) and acoustics (like the howls). However, other forms of communication have been overlooked, such as the use of visual cues, which could be just as important.
In fact, there are several reasons to think that visual communication in mammals could be used more frequently than previously thought.
permanent visual signals
The first reason has evolutionary roots. Mammalian coloration has evolved as a signal for intra- and interspecific communication.
Additionally, visual signaling through physical markings, such as bites and scratches, is permanent and therefore has the advantage of being long lasting. It is less likely that environmental factors such as rain or snow affect their detectability compared to communication via chemical signals.
The temporary permanence of visual cues it can, in this way, allow individuals to reduce repeat visits to these strategic marking points. Thus they have more time for other activities such as foraging and reproduction.
For the solitary species and that generally reach low population densities, such as Brown bears (Ursus arctos)whose direct interactions between individuals are infrequent, it may be very important to develop communication channels that, in a lasting way, can communicate their identity, age, sex and location.
The chemical language of bears
To date, studies of bear communication have highlighted chemical signals as the primary form of communication.
Ursids essentially use three forms of olfactory communication:
But since the beginning of the eighties, some researchers had shown their curiosity towards the marks that brown bears leave on the trees.
The function of biting and scratching the barks of trees has given rise to several hypotheses mainly related to glandular scent deposition (ie chemical signaling). However, these ideas had never been tried to be demonstrated experimentally.
These visual markings therefore became a unique but unexplored opportunity to investigate new possible forms of visual communication in terrestrial mammals.
markings on trees
A group of researchers, also intrigued by these striking marks that bears leave on trees, decided to carry out a series of experimental works to test the idea that, in addition to chemical communication, brown bears can also use visual cues for intraspecific communication.
To test our starting hypothesis, we hide the marks left by bears in the trees from the Cantabrian mountain range with pieces of bark from the same species of the marked tree, and we record with camera traps the behavior of bears when passing through these trees.
We found out so these visual markings were specific to adult males during the mating season (mainly from April to June in the study area) and that they were always linked to the rubbing of the body on the trunks (and sometimes to the traces left by the feet on the ground). This behavior suggests that visual and chemical signals could be complementary.
In fact, they could provide different information. The visual markings would act as an indicator of the single size and therefore of dominance status of adult males looking for mating opportunities.
New ideas that open paths
Beyond what we have been able to learn about the ways in which species as charismatic and inaccessible as the brown bear communicate, we have had the opportunity to learn a great lesson. It is about the importance of disengage from solidly established ideas and use our imagination to open new paths based on scientific evidence.
The ecology Its main objective is to try to explain the multiple and different patterns of biological systemsas well as the behavior of the species. Meeting this goal is not easy, especially considering the impressive diversity and richness that characterizes the natural world.
In this scenario, the greater the variety of biological models on which we base ourselves, the closer we will come to understanding the rules that govern the systems, leaving aside an ecology oppressed by the needs imposed by productivity, where we limit ourselves to the study of biological models that more easily provide fast and easily publishable results.
If we lose this freedom, we are also losing essential information to understand the enormous variety and complexity of patterns observed in nature, of strategies employed, of complex structures, pathways, and evolutionary crossovers.
Physicist Freeman Dyson, speaking of the paths traveled by geographical exploration, said that at first, when everything was undiscovered, big goals were the only goal of the explorers. For George Everest, reaching the top of the mountain that would later bear his name was his only goal, and everything that stood between him and Everest, the rivers, the jungles and the plains, were only obstacles.
In the same way, ecology, in its origins and due to a lack of knowledge, had to have great objectives, and these objectives were the main patterns, the universal laws that were at the base of the functioning of ecosystems and species.
Now, in many cases, it is a question of details, sometimes small, but important.. Everything that before could seem marginal or uninteresting, those rivers or those barely explored jungles, is what now still retains its richness and interest. And it is these apparently minor, but unknown paths, where we have to look.