Cheaters among pollinators: Floral traits drive spatiotemporal variation in nectar robbing and thieving in Afrotropical rainforests

SUMMARY Nectar robbing and thieving can substantially affect the reproduction of animal-pollinated plants. Although the intensity of nectar exploitation remains unexplored at the community level, it probably varies along environmental gradients. We video-recorded flower visits to animal-pollinated plants in Afrotropical rainforests along a complete elevational gradient in the wet and dry seasons on Mount Cameroon. We analysed how the proportion of nectar robbing and thieving in the communities changes spatiotemporally, especially in association with the floral traits of the flowering plants. We recorded 14,391 flower visits, of which ~4.3% were from robbers (mostly bees and birds), and ~2.1% were from thieves (mostly flies, bees, and moths). Of the 194 studied plants, only 29 and 39 were nectar robbed and thieved, respectively. Robbers and thieves were most frequent at mid-elevations, with more frequent robbing in the wet season and thieving in the dry season. These trends were linked to the local composition of floral traits, and cheating groups’ associations to particular traits. Floral traits that prevented thieving made flowers susceptible to robbing, and vice versa. Spatiotemporal variation in floral traits across drives the cheating behaviour of flower visitors across communities, while indicating a trade-off between preventing nectar robbing and thieving.