Résumé : |
Unmanned Aerial Systems (UAS) have been used for decades in the military field, mainly in dangerous or tedious missions where it is preferable to send a vehicle equipped with sensors than to use human piloted conventional aircrafts for information gathering. In recent years technology has advanced, the market has grown exponentially, prices have descended and the use of the systems is simpler, which has led to the incorporation of the UAS to the civilian world. UAS have proven useful in ecology related tasks, such as animals monitoring and habitats characterization, and their potential for spatial ecology has been pointed out, but to date there are just a few studies addressing their specific use in conservation biology. This Ph.D. thesis attempts to fill the gap of knowledge in practical functions of small UAS in conservation biology. It describes for the first time the use of these systems in an immediately applicable way for impact assessment of infrastructures and protection of endangered species. It also presents UAS as a tool for obtaining highresolution spatiotemporal information, which helps to understand habitat use in rapidly changing landscapes. Furthermore, it demonstrates that these systems can provide information as valid as the obtained by conventional techniques on the spatial distribution of species in protected areas. The experiments performed in the frame of this thesis show that low cost small UAS equipped with embarked cameras that provide high-resolution images offer the possibility of monitoring the environment at the researcher’s desired frequency and revisiting sites to perform systematic studies, which is valuable for ecological research. The results also revealed that UAS use in conservation biology has some constraints, mainly related with the scope of the missions, the limiting costs of the systems, operating restrictions associated to weather, legal limitations and the need of specialized personnel for operating the systems, as well as some difficulties for data analysis related with image processing. Overall, given the novelty of the subject and the importance it is expected to have in the near future, I consider that providing information on the capabilities and limitations of UAS, based on practical experiments in conservation biology, is not only of scientific interest but combines environmental and industry interests, which brings added value and usefulness of this thesis to society. |