There is always room for one more: mass visitation by nectarivorous bats recorded at urban Sumaúma trees (Ceiba pentandra)

Abstract Background In tropical South America, Ceiba pentandra (Malvaceae) is a native chiropterophilous tree frequently found in cities that stands out as a potential substantial floral resource for synanthropic bats, which exhibit unusual swarming behaviour when interacting with this species. We documented this phenomenon of mass visitation by bats to C. pentandra, shedding light on the potential of this species as key resource for bats in urban ecosystems. Methods We conducted fieldwork observations observations in a green infrastructure in the city of Recife in Northeastern Brazil, during the 2021 reproductive event of Ceiba pentandra. Five flowering individuals were selected for focal observations of bat visitation. Bats and other floral visitors were monitored over ten non-consecutive nights. Diurnal visitors were also recorded. Results We found that C. pentandra was massively visited by Glossophaga soricina and Phyllostomus discolor, with groups larger than 25 bats of each species constantly visiting the plants throughout the night. In addition to bats, we also observed Sphingidae moths at night, as well as birds and bees at day. Conclusions Contrary to visitation behaviour with a lower number of visits per night observed for most chiropterophilous plants in natural environments, the continuous and high number of visits to C. pentandra of two species at the same time is a poorly described phenomenon for nectarivorous bats. Our results highlight that, although this mass visitation behaviour within the groups still needs to be explored in depth.