Unmanned Aircraft System For Surveying Large Herbivores

With the continuous growth of the population and the rapid development of the local economy,the contradiction between protection and development has become increasingly prominent.The survival and development of nature reserves are facing a severe challenge.In recent years,the population number of large herbivores in nature reserves has gradually increased.It results in increasing pressure on grassland livestock and causing serious impact on grassland ecosystems.Therefore,there is an urgent need to investigate the status and species of the large herbivores.However,the existing technologies of monitoring the large herbivores are not enough to support the smooth and efficient development of related work.Based on the Unmanned Aircraft System(UAS),this paper investigates the large-scale herbivores in Longbao Wetland National Nature Reserve.The remote-sensing images of 63.69 km~2were acquired by the UAS,and the images were mosaicked by the professional software Pix4Dmapper.The large herbivores in the study area were identified by visual interpretation.Finally,the statistical analysis of the interpretation results and the estimation of the population number were performed.The effects of image mosaic and the noise of UAS on animal identification were analyzed.The results show that the photography of UAS is very suitable for monitoring large herbivores.The technology for UAS is expected to become an important technical method for investigating and monitoring the population number and distribution of large herbivores and provide a scientific basis for better management of animal resources and the formulation of related protection strategies by protected area management departments,which is beneficial to the protection of biological resources in the future.It is conducive to the protection of biodiversity,the building of ecological security barriers,the safety and stability of various natural ecosystems and the improvement of the quality of the ecological environment.Through this study,the main conclusions are as follows:(1)Through visual interpretation,the large herbivores found in the study area are Tibetan sheep and yaks in this paper.No other large wild herbivores have been found.Due to the lower resolution of the images,black-necked crane was not identified in the study area.(2)Statistical analysis shows that there are a large number of livestock(Tibetan sheep and yaks)distributed in the core area and buffer area of nature reserves.It can be seen that there are still a large number of herdsmen in the nature reserve that have not moved out.According to the national land area of the Longbao Wetland National Nature Reserve,the population number of large herbivores in the nature reserve amounts to 23131 sheep units.Figure 4-2 shows that the large herbivores in the nature reserve are mainly distributed in the core area.(3)Remote image mosaic of UAS has little effect on the population number of large herbivores.Comparing the population number of large herbivores identified from the overall mosaic image with the population number of large herbivores identified from the four flightlines,the relative error between the two was only 1.98%.The noise of UAS has little effect on the behavior of large herbivores.Compared to the population number of large herbivores identified within a range of 0-100 meter,the population number of large herbivores identified within a range of 100-200 meter did not change significantly.(4)UAS have many advantages such as high image resolution,high efficiency,and accessibility to inaccessible areas.This study demonstrates that UAS can be used as a powerful tool to monitor large herbivores.