1) Dataset Title Multi-temporal UAV orthomosaics of an Adélie penguin colony at Cape Hallett, Ross Sea, Antarctica (2018–2025) 2) Purpose of Data Acquisition To establish a spatially co-registered multi-year UAV orthomosaic time series for long-term ecological monitoring of the Adélie penguin (Pygoscelis adeliae) breeding colony at Cape Hallett, Antarctic Specially Protected Area No. 106 (ASPA No. 106), Ross Sea, Antarctica. Because no real-time kinematic (RTK) ground control network is available at the site, absolute positional offsets of several metres accumulate between survey years. The dataset was therefore designed to achieve relative spatial consistency across the time series by co-registering all annual orthomosaics to a common 2018 master reference through an automated image-to-image registration workflow. 3) Brief Description Six austral-summer UAV campaigns (2018, 2021, 2022, 2023, 2024, 2025) acquired a total of 4,471 nadir RGB images over the Cape Hallett Adélie penguin colony (72°19'S, 170°13'E).The 2018 campaign, conducted with a DJI Matrice 600 hexacopter and a Canon EOS 5DS DSLR camera (GSD 0.72 cm/pix), serves as the master reference orthomosaic. Orthomosaics from the five subsequent campaigns (2021–2025), acquired with DJI consumer-grade quadcopters (Mavic 2 Pro, 2 Enterprise Advanced, 3 Pro, 4 Pro), were co-registered to the 2018 master using an automated pipeline combining deep learning-based (LightGlue + SuperPoint) and classical (SIFT, ORB) feature matching with four candidate geometric transformation models (translation, similarity, affine, second-order polynomial). Independent tie-point validation yielded median post-warp residuals of 2.02–2.38 m across all campaigns. 4) The deposit contains: (1) the 2018 master orthomosaic, (2) five pre-registration slave orthomosaics, (3) 20 co-registered orthomosaics (5 years ×4 models), (4) Agisoft Metashape photogrammetric survey reports (PDF) for each campaign, (5) 47 surveyed rock markers as shapefile and CSV, (6) independent post-warp residual measurements (20 CSV files), and (7) adopted co-registration model metadata (JSON) per slave year. All spatial data are in WGS 84 / UTM zone 59S (EPSG:32759). 5) Keywords UAV, orthomosaic, Adélie penguin, Cape Hallett, Ross Sea, Antarctica, image co-registration, time series, Structure-from-Motion, LightGlue, SuperPoint, ASPA 106, colony monitoring 6) Spatial Extent 72°19'S,170°13'E(Cape Hallett, northern Victoria Land, Ross Sea, Antarctica) Bounding box (EPSG:32759): Easting 472,940–474,305 m, Northing 1,974,587–1,975,656 m 7) Temporal Extent 2018-11-25, 2021-11-21, 2022-11-20, 2023-11-26, 2024-11-21, 2025-11-21 8) Data Formats GeoTIFF (orthomosaics), PDF (photogrammetry reports), Shapefile (reference markers), CSV (residual statistics, marker coordinates), JSON (adopted model metadata)