A baseline waterbird occurrence dataset for Miyun Reservoir, Beijing, China.

Background: Miyun Reservoir is north China's largest artificial reservoir and vital drinking water supply for Beijing and is a key stopover for migratory birds along the East Asian-Australasian Flyway (EAAF). Previous literature indicates that continuous high-water-level regulation starting in 2015 may alter shallow wetland habitats and migratory bird distribution patterns; previous studies reported a decline in reservoir waterbird occupancy from 79% (2018) to 56% (2022). However, no complete annual-cycle synchronous waterbird census covering the full reservoir basin has been published to date. This paper releases standardised synchronous survey data collected across Miyun Reservoir in 2023. This one-year dataset provides a spatial and temporal baseline for future multi-year ecological modelling and comparative analysis, rather than direct evidence to quantify long-term ecological changes driven by reservoir water management. New information: We publish the first full annual-cycle standardised waterbird dataset covering all 14 fixed sampling stations of Miyun Reservoir, with four seasonal synchronous surveys implemented between 10 April and 16 October 2023. A total of 32 waterbird species and 25,180 individuals were recorded, generating 198 unique Darwin Core-compliant occurrence records archived on GBIF with a permanent DOI (https://doi.org/10.15468/vfjx35). The dataset delivers baseline abundance and distribution data for resident and migratory waterbird assemblages within the reservoir basin.