Contrasting seasonal reproductive patterns in two sympatric carpenter bee species (Xylocopa frontalis and X. grisescens) in Brazilian savanna

Understanding how species differ in the timing of reproductive activity and in their responses to environmental conditions can provide insights into patterns of resource use and coexistence in seasonal environments. Here, we investigate the reproductive dynamics and nesting phenology of two large sympatric carpenter bees, Xylocopa frontalis and X. grisescens , in the Brazilian savanna. We hypothesized that X. frontalis and X. grisescens differ in nesting behavior and reproductive phenology, resulting in reduced temporal overlap in brood production. Over three consecutive years (2020–2022), we monitored bamboo trap-nests in two savanna areas of Central Brazil, recording nest occupation, foundation, reuse, longevity, brood cell production and climatic variables. Our results revealed that the two species showed contrasting nesting and reproductive patterns. Xylocopa frontalis exhibited shorter nest longevity (2.88 months on average) and a multimodal reproductive pattern with the concentration of brood production during the rainy season, particularly in February–March. Its brood-cell production was positively associated with minimum temperature and relative humidity. In contrast, X. grisescens had longer nest longevity (4.04 months), and a more temporally diffuse reproductive pattern, with brood production extending into drier periods and the dry-to-rainy season transition. Brood production in X. grisescens was negatively associated with relative humidity and positively associated with minimum temperature. Overall, the contrasting seasonal patterns resulted in reduced temporal overlap in brood production between the two species. These differences may reflect species-specific responses to seasonal environmental conditions and life-history characteristics and may contribute to reducing temporal overlap in resource use. Our findings highlight the importance of considering species-specific phenology when examining the coexistence of sympatric pollinators in highly seasonal tropical environments.