<em>Mikania micrantha</em> is one of the most aggressive invasive alien plant species in low-elevation landscapes of Taiwan. This study used fixed-wing UAV imagery to monitor its flowering-season distribution in a primary monitoring area north of Liyu Lake, Hualien County, eastern Taiwan. Rather than treating the dataset as a continuous annual time series, the analysis was based on three flowering-season observation epochs acquired on 14 January 2021, 7 December 2021, and 4 January 2024. UAV imagery was collected using an eBee X platform and processed in Pix4Dmapper Pro to generate high-resolution RGB orthomosaics with an average ground sampling distance of 3.08 cm/pixel. <em>M. micrantha</em> patches were delineated through manual image interpretation, and kernel density estimation (KDE) was applied to evaluate changes in spatial concentration and hotspot distribution. The interpreted infestation area decreased from 2,094.74 m² in the first epoch to 1,361.94 m² in the second, then increased to 1,799.09 m² in the third. KDE results showed a similar pattern, with persistent core infestation zones and renewed expansion in surrounding areas, including a new hotspot in the southeastern part of the monitoring area. These findings demonstrate the practical value of UAV-based monitoring for adaptive invasive plant management.