Legacies with complex meaning: In addition to intraspecific communication, marking sites of certain animals can apparently also serve as a source of information for other species. This is suggested by a study using the example of cheetah marking trees in the African savannah. Using surveillance camera footage, the researchers found that some animal species visited and sniffed the big cats' communication hotspots noticeably more often than control trees. They see this as a sign that cheetah scents are also communicating something to these animals. There seems to be some kind of network for intra- and interspecies communication, say the scientists.
“I was here”: Some animals convey this and other information by leaving scent marks or their business in often conspicuous places, which can then be sniffed out by others. Research into this behavior has so far focused on its role in communication within species. It is known that the markings can provide the animals in a population with various information: about territorial ownership claims, willingness to reproduce, health status or the diet of the individuals. However, little research has been done to date on how other animal species react to the olfactory communication of a specific species in their habitat. In order to get basic information, a research team from the Leibniz Institute for Zoo and Wildlife Research (IZW) in Berlin carried out an investigation into the case of the marking sites used by cheetahs (Acinonyx jubatus) in a study area in Namibia.
More than information for conspecifics
In an earlier study, the wildlife biologists had already shown the importance of certain marking trees in the intraspecific communication of these big cats. “In our new study, we now monitored cheetah marker trees and similar-looking nearby control trees. These too were conspicuous, solitary and large specimens, which is basically typical for cheetah marking trees,” explains co-author Jörg Melzheimer from the IZW. "We used this comparative approach to obtain information as to whether mammalian species come to the trees only for intraspecies communication or also for interspecies communication." To do this, the scientists used recordings from camera traps to record which animal species visited both tree types and how often.
The evaluations revealed: During the 65 days of monitoring, a total of 29 species of mammals visited the trees in the focus of the cameras. The researchers found a fundamentally higher diversity of visitors to the cheetah marking trees than to the control trees. The results for three species were particularly striking: African wildcats (Felis lybica lybica), black-backed jackals (Lupulella mesomelas) and warthogs (Phacochoerus africanus) visited and sniffed the cheetah marker trees noticeably more often than the control trees. The researchers interpret this as an indication that these animal species received information from the cheetah scents. Other animal species, on the other hand, exchanged olfactory information equally frequently at cheetah marking trees and control trees. This in turn suggests that these species generally like to use conspicuous trees for their own communication, but do not specifically select cheetah marking trees for this purpose, the researchers explain.
Various motifs possible
As for the special visitors, first author Sarah Edwards from the IZW says: "It is likely that small carnivorous species such as the wild cats and the black-backed jackals visit the cheetah marking trees to estimate when cheetahs were last at the trees. Warthogs, on the other hand, are omnivores and opportunistic scavengers, so they probably also eat undigested prey residue in cheetah droppings that may be found there,” explains the wildlife biologist. As the researchers further report, there were also counter-examples in the visit rate: duikers (Sylvicapra grimmia) clearly avoided the marking trees compared to the control trees. This seems plausible, because these are important prey animals for cheetahs. Therefore, the duikers probably stay away from the areas smelling of the predators.
The fiercest predators in the project's study area also visited the trees, surveillance cameras showed: leopards, however, came to both the cheetah marker trees and the control trees and sniffed, urinated, clawed and rubbed themselves on them. "Leopards also use conspicuous trees for their intraspecific communication and may at the same time demonstrate their presence to the cheetahs on the cheetah marking trees," says co-author Bettina Wachter from the IZW.
Overall, the study results provide evidence that mammals in Namibia maintain an interspecies communication network, say the scientists. Presumably other species' marking sites play a similar role to the cheetah's marking trees. Further research potential is therefore emerging: "Future studies on the interspecific communication of different species in different populations and ecosystems could reveal more details about the complexity of the communication networks," the researchers write in conclusion.
Source: Leibniz Institute for Zoo and Wildlife Research, specialist article: MAMM BIOL. Doi: 10.1007/s42991-022-00284-w