Citizen science complements functional, taxonomic and spatial coverage of bird collections in the Pantanal, the world's largest tropical wetland

Species occurrence data are essential for understanding biodiversity patterns; however, the necessary fieldwork to generate them demands substantial resources and time. Citizen science programmes, such as birdwatching initiatives, can complement traditional sampling by expanding data collection. The Pantanal, one of the world's largest wetlands, hosts the highest avian diversity among such ecosystems and attracts intensive visitation by birdwatchers. However, scientific sampling in the region remains limited, leading to knowledge gaps. We analysed bird records from biological collections ( n = 5050) and citizen science observations ( n = 16 189) to examine the complementarity in taxonomic and functional diversity, as well as spatial and temporal coverage. The two datasets shared 318 species. Biological collections documented 62 exclusive species, whereas citizen science recorded 47 species found only in that source. Citizen science records captured a wider range of species traits but exhibited a slightly narrower distribution of traits than biological collections. Although both datasets occupy much of the same functional space, they remain complementary because each includes species with distinct traits. Records from both datasets concentrate in the northern Pantanal but show distinct spatial patterns. Citizen science provides approximately 2.4 times the spatial coverage of biological collections, with little spatial overlap between records from the two sources. However, the central and most of the boundary regions remain under‐sampled by either dataset. Both datasets negatively correlate with monthly flooded area extent, reflecting limited knowledge of avian diversity during flooding, when up to 80% of the Pantanal is submerged. Our results highlight that citizen science and biological collections can complement each other in capturing bird distribution, diversity and functional traits, which ultimately underpin ecosystem services at regional scales. Expanding similar integrative assessments across different ecoregions will improve biodiversity monitoring, refine conservation strategies and strengthen the value of citizen‐generated information in global ecological research.