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202501/16
The latest ecological survey conducted by the Nantou Branch of the Forestry and Nature Conservation Agency (FANCA Nantou) successfully located the rare and elusive Australasian grass-owl (Tyto longimembris) by collecting environmental sound sources using recorders in the lower reaches of the Zhuoshui River. This marks the first confirmed presence of the rare Australasian grass-owl in central Taiwan, expanding its known range beyond southern Taiwan. This discovery holds considerable significance for the protection of Taiwan's native bird species and simultaneously introduces new challenges and visions for biodiversity conservation efforts.
The Australasian grass-owl is a nocturnal owl that prefers open grasslands and agricultural areas. It feeds on small mammals and plays an important ecological function in controlling the number of rodents in the environment and reducing crop damage. Due to the substantial overlap between its habitat and areas of human activity, the Australasian grass-owl's living space is experiencing continued compression due to factors such as land development. The improper application of pesticides in cultivated fields indirectly contributes to Australasian grass-owl mortality through the ingestion of poisoned wild mice. The use of bird netting also poses a risk of inadvertent trapping, increasing the likelihood of injury or death. Furthermore, as Australasian grass-owls prefer to build their nests on the ground, they are easy targets for attacks by stray dogs. All of these factors mean that the Australasian grass-owls are facing a severe survival crisis. Due to the low number of individuals and the unknown status of the entire population, the Australasian grass-owl is listed as a "protected endangered wildlife species" under the Wildlife Conservation Act.
According to currently known related investigations, the number of Australasian grass-owls found within the distribution range in southwestern Taiwan is relatively stable. However, five to seven decades ago, records show that it was not uncommon to find Australasian grass-owls in low-elevation mountains and farmland environments in central Taiwan, in regions such as Taichung, Nantou, Changhua, and Yunlin. However, according to a commissioned survey of the Forestry Bureau (before its restructuring into the FANCA) in 2018, the survey sample areas in these regions showed almost no sighting records of Australasian grass-owls. It is speculated that population development in the low-elevation mountainous regions of central Taiwan resulted in a significant reduction of suitable habitat for the Australasian grass-owl, contributing to a substantial population decrease. Until recent years, there have been records of sightings of the Australasian grass-owl near the mouth of the Zhuoshui River in Mailiao and the Ershui Ecological Conservation Station of FANCA Nantou, lighting up a spark of hope for the reappearance of Australasian grass-owls in central Taiwan. Therefore, the FANCA Nantou initiated an investigation project and commissioned a research team to use an automatic sound recorder that can record continuously with no interruptions over a long period of time. The aim was to passively collect environmental sound sources and analyze whether there were calls of the Australasian grass-owls to confirm their presence. Preliminary monitoring results showed that 6 hotspots with frequent Australasian grass-owl activities were detected across the lower reaches of Zhuoshui River to the river mouth, and grass-owl activities were even recorded at the mouth of the Zhuoshui River every month of the year.
Lee Cheng-Hsien, Director of FANCA Nantou, said that the investigation confirmed that the endangered Australasian grass-owl has reappeared in the Zhuoshui River basin after decades. This is encouraging news and an opportunity to further promote biodiversity conservation. The FANCA has promoted the Taiwan Ecological Network since 2018. FANCA Nantou has begun to implement the construction of a regional ecological network under its jurisdiction in Nantou, Changhua, and Yunlin Counties. It has also listed the Australasian grass-owl as a species of concern in the Changhua-Yunlin coastal wetland conservation corridor, which also includes the mouth of Zhuoshui River. Although Australasian grass-owl activities in the Zhuoshui River basin show signs of this species recovering in the local ecosystem, environmental changes, pesticide use, habitat destruction, and harassment by stray dogs and cats still pose serious threats to the survival of the Australasian grass-owl. FANCA Nantou will continue to investigate and monitor the key areas under its jurisdiction to keep abreast of grass-owl activities. It will leverage the Taiwan Ecological Network to facilitate human networking and integrate resources from diverse sectors, fostering cross-domain cooperation and public-private collaboration. These efforts aim to maintain and create wildlife-friendly habitats, working towards a future of coexistence and prosperity for humans and wildlife, including the Australasian grass-owl.