PhD Update: Resource partitioning and coexistence in colonial frugivorous birds

Intra-specific competition is especially challenging for colonial species because the number of individuals is higher near the colony, and resources are depleted faster. Coexistence with conspecifics hence depends on mechanisms that minimize competitive interactions and favor resource partitioning. In the first chapter of my thesis, I analyze how individual differences in movement behavior facilitate coexistence, and the cost associated to different movement strategies. I used location and accelerometer data from 21 oilbirds, a cave-dwelling colonial tropical frugivore, from Cueva del Guacharo in Venezuela. I characterized movement patterns and the length of the periods they roost outside of the cave, and classified individuals into one of three movement strategies. Oilbirds reduced inter-individual competition by combining spatial segregation with site fidelity. I found that the species performs partial nomadic migrations, with individual variation in time, duration and destination. Migratory individuals expended less energy than individuals that perform any other strategy by reducing the number of commute flights between the cave and the foraging areas. These differences could have fitness consequences and highlight the importance of mechanisms that enable stable coexistence in colonial species. I will also present ideas and progress on further chapters that include collaborations in Colombia, where we have tagged 51 oilbirds, and will study the effects of habitat fragmentation on the cost of movement. Feedback and ideas will be appreciated.