# Identification of Ratholes in Desert Steppe Based on UAV Hyperspectral Remote Sensing
## 1 Introduction  
Grassland ecosystems play a major role in regulating the process of climate change on Earth and are an important production base for the development of grassland livestock farming, as well as an important ecological barrier [1]. In recent years, grassland ecosystems have been destroyed to different degrees due to both natural and human factors [2, 3]. Among them, grassland rodent infestation is an important cause of grassland ecosystem degradation. A large number of vermin occupy grassland resources, digging and making holes, resulting in a large reduction in the grassland area and a decrease in the livestock carrying capacity of grasslands, which has caused serious economic losses among herders. Pest rats belong to the rodent group. According to a previous survey, there are more than 2000 species of rodents worldwide, carrying about 200 species of pathogens, accounting for about 25% of the pathogens in humans [4]. Among dozens of rodent-borne diseases, plague, hemorrhagic fever with renal syndrome (HFRS), and leptospirosis are infectious diseases that are legally prevented in China, which pose a serious threat to human life and health safety [5]. China has one of the largest grassland areas in the world, with a natural grassland area of approximately 400 million hectares, accounting for 40% of its total land area androughly 13% of the world's total grassland area [6; 7]. With a total grassland area of 88 million hectares, which accounts for 20.06% of the national grassland area, Inner Mongolia is the second largest province in China in terms of grassland area, and the largest in terms of pastoral area. A previous survey revealed that the grassland rodent pest area in the Inner Mongolia Autonomous Region covers 6.54 million hectares, with a severely affected area of 2.83 million hectares. The expansion of grassland rodent pest areas, coupled with the sharp increase in pest numbers, not only poses a significant threat to the ecological balance of grasslands, causing severe degradation, but also increases the risk of a plague outbreak. Rapid and accurate positioning of the geographical coordinates of rodent holes, combined with real-time and dynamic monitoring of changes in their numbers and distribution, is a crucial method to contain the occurrence of rodent pests. Grassland degradation mainly consists of vegetation degradation as well as soil degradation. Vegetation degradation refers to the reduction in high-quality forage production and the decline in vegetation species. Soil degradation refers to the reduction in organic matter content and soil erosion. Soil degradation is the precondition for vegetation degradation, and vegetation degradation is the inevitable result of soil degradation. Pest rats destroy soil and gnaw pasture, which are important causes of grassland degradation. Therefore, investigating the number of grassland pest rodent holes is an important basic link to monitoring grassland degradation and assessing the degradation level. The number of ratholes as well as the geographical coordinates can be manually surveyed with high accuracy. Based on the sample scale (0.25-1 hectares), the hole coefficient of pest rats can be calculated, and the density of rats can be investigated by plugging holes and pinning lines. By observing whether there are signs of activity around the holes, researchers can effectively differentiate between active and abandoned holes [8]. However, manual surveys are not only time-consuming and labor-intensive, but also, in the event of rodent infestation, hindered by the risk of potential virus transmission, threatening the lives of investigators [9]. Satellite remote sensing is a useful tool for large-scale spatial investigations. By obtaining satellite data, vegetation index calculations can be performed to achieve the estimation of above-ground biomass [10; 11].