<p>Tree cavities are valuable resources for wildlife worldwide. Cavities serve various purposes including breeding, roosting, protection, thermoregulating and foraging. Among the resources provided by cavity-bearing trees is accumulated rainfall water used by birds for drinking and bathing. We surveyed herein water-drinking birds at tree cavities in Brazil. We searched for photographic records in the WikiAves citizen science platform using the “drinking water” filter in the Advanced Search. The resulting ~ 9800 photographic records included 44 ones that showed water-drinking birds at tree cavities. The birds were recorded drinking rainfall water accumulated in cavities at bifurcations, depressions, and broken branches on the lateral or superior sides of tree trunks. The records were mostly from the Atlantic Forest domain and comprised 31 species in 14 families. Woodpeckers, toucans, parrots, and songbirds (Piciformes, Psittaciformes and Passeriformes) dominated the records. Most records (84%) had water-drinking confirmed by visualization of water drops and wet parts of the bill, comments provided in the “Observations by Author” platform field, and email messages sent by citizens replying to our requests. Drinking was not confirmed in 16% of records, which we used with reservations. Of the total number of species, 61% are known to nest in tree cavities, whereas 39% nest in other structures. Future studies could examine temporal variation of water-cavity drinking behaviour by birds (and water intake by other vertebrates as well). Our survey strengthens the view that photographic records available in citizen science platforms greatly increase the knowledge about bird behaviour in the Neotropics.</p>