Spatial Resolution Impact Assessment for Long‐Term Population Monitoring of Adélie Penguin Guano

Adélie penguins (Pygoscelis adeliae) are key indicators of the Antarctic ecosystem, and remotely sensed guano stains offer an efficient means of estimating breeding abundance. Landsat medium‐resolution (MR) imagery enables long‐term monitoring through its archive. However, the effect of spatial resolution on detection accuracy and abundance estimates remains unquantified. This study evaluated resolution‐dependent errors using unmanned aerial vehicle (UAV; 0.1 m), very high‐resolution (VHR; 1.24 m, WorldView‐4), and MR (30 m, Landsat 8) imagery acquired concurrently over the Cape Hallett colony in November 2018. UAV‐based delineations were used as reference data to assess guano detection accuracy and to perform Monte Carlo and Poisson‐based simulations. VHR imagery achieved high accuracy (F1 = 0.73; omission = 21%), whereas MR imagery showed large commission (59%) and omission (21%) errors. Detection errors rose nonlinearly with coarser resolution, reaching 97% at 30 m. Abundance estimates were sensitive to apparent density; using the Antarctic mean (0.34 nests m −2 ) sometimes gave lower errors than the UAV‐based value (0.44 nests m −2 ). These results provide a quantitative framework linking spatial resolution, detection error, and estimation uncertainty, emphasizing the need for UAV‐based validation and colony‐specific calibration for reliable long‐term monitoring of Antarctic penguin populations.