Temporal partitioning of pollination and seed dispersal interactions in two sympatric mistletoes

Mistletoes are aerial parasitic plants that play a key role in forest ecosystems, promoting biodiversity by providing food and microhabitats for many animals. Here, we assessed interaction partitioning on two sympatric species of mistletoes (Tristerix aphyllus and Tristerix verticillatus), which coexist in a semi-arid environment. Tristerix aphyllus is a holoparasitic mistletoe specialized on cacti, while T. verticillatus is hemiparasitic and parasitizes a wider variety of trees and shrubs. We used camera traps to conduct a 2-year survey of the interactions of T. aphyllus and T. verticillatus with their mutualists: the pollinator Sephanoides sephaniodes and the seed disperser Mimus thenca, two generalist bird species that largely rely on these mistletoes. We analysed plant phenology, annual and daily activity patterns of S. sephaniodes and M. thenca, and the seasonal effects of temperature on visitation rates. Both mistletoe species have overlapping flowering and fruiting seasons, resulting in complex interactions with their main mutualists. Furthermore, daily and annual activities of S. sephaniodes and M. thenca overlapped in both mistletoe species, depending on the phenological stage of the mistletoes. Our results highlight the importance of phenological overlap for mutualistic interactions, as sympatric species with similar phenologies tend to provide more floral and fruit resources for mutualistic animals, thereby reinforcing the ecological dynamics of these communities.