Wildlife monitoring – what is that actually?
Wildlife monitoring is the continuous documentation and monitoring of wildlife populations in their natural habitats. Monitoring collects data on the occurrence, distribution and frequency of wild animals. Concerning the lynx in Thuringia, the use of monitoring answers the question of where lynx already live in the Free State and how numerous they are. Three main methods are used in our project to monitor the lynx: photo traps, GPS telemetry and genetic monitoring.
How do photo traps work?
Photo traps are automatic cameras triggered whenever movement and a heat signature are registered in their detection field. Photo traps have become a standard method of wildlife research in recent decades, especially for the observation and population assessment of nocturnal, secretive animal species.
In the case of lynx, researchers also take advantage of the fact that the animals can be individually distinguished from each other by their fur patterns. It is, therefore, possible to assign the photo trap images to individual lynxes and to count the photographed lynxes in this way.
Of course, not every lynx within a surveyed area may be captured by the cameras. However, with the help of modern statistical methods, it is possible to estimate the actual number of lynx and/or their population density in the study areas from the number of photographed lynx and the frequency and distribution of the images.
Why are lynx tagged with collar transmitters?
All lynx released as part of our project are equipped with GPS collar transmitters. In this way, we can follow the fate of the lynxes after their release and monitor them closely. The transmitter sends us the lynx’s whereabouts 1-2 times daily. This gives us information about the spatial use and migration behavior of the released lynx.
GPS transmitters are a standard method of modern wildlife research. The transmitters are designed in such a way that they do not interfere with the animals’ natural way of life. At the end of the batteries’ life (after about one year), the transmitter is opened by an automatic mechanism, and the lynx is freed from the transmitter.
What is genetic monitoring?
When a lynx has killed a prey animal, saliva samples of the lynx can often be obtained from the still-fresh carcass. These samples can be examined in the laboratory to create a genetic profile (a genetic fingerprint) of the lynx. The sampling of lynx carcasses is usually done by volunteer lynx officers of the Thuringian hunting community. Other potential sources for obtaining genetic material from lynx are feces and hair. These are, however, much more difficult to find in the field than kills.
Genetic data are a valuable complement to the other two monitoring methods. Genetic profiles can be used to determine the degree of relationship between lynx. In the case of immigrant lynx, the genetic data also provide information on the origin of the immigrants. Finally, through long-term genetic monitoring, the genetic diversity of the emerging lynx population of the Thuringian Forest can be continuously monitored.
What have we found out so far about the lynx in Thuringia?
In 2019, we started systematic photo trap monitoring in the Thuringian Harz Mountains and in the forest areas that lie to the south of the Harz Mountains. Within the framework of this monitoring, we have already been able to take more than 200 photos, which are attributable to several individually distinguishable lynx.
While the presence of the lynx in the Thuringian Harz was certainly not a big surprise, the more fragmented forest areas of the Eichsfeld in north-west Thuringia were of particular interest to us, as these forest areas represent a possible dispersal corridor for the lynx in Thuringia.
In the very north of the Eichsfeld, we have been able to detect two lynx since 2019, which have established permanent territories there, in the border area to Lower Saxony. One of these lynxes is a female with the designation B1073w, which has regularly given birth to offspring in the northern Eichsfeld since 2020. Nevertheless, permanent colonization of the rest of the Eichsfeld and the forest areas further south has so far not taken place.
In the Thuringian Forest, we started photo trap monitoring in the fall of 2021, initially in an area of about 900 square kilometers in the central Thuringian Forest. There, too, we have already photographed lynx, but only three pictures have been taken by spring 2023. The comparison with the many photos taken in the north-west of Thuringia makes it clear that the lynx is still a rare guest in the central Thuringian Forest. Generally, these are probably roaming males.
How does the monitoring of the lynx in the Thuringian Forest continue?
All lynx released in our project are equipped with collar transmitters. This allows us to closely monitor their further fate for about a year. In addition to telemetry, photo traps are also used over a large area right from the start. In this way, the released lynx (and possibly also their offspring) can continue to be observed even after the collar transmitters have failed. In addition, it can be assessed whether the newly emerging population in the Thuringian Forest continues to grow due to the immigration of further lynx (e.g. from the Harz Mountains). The data from the photo traps will be supplemented by the data from the genetic monitoring.