Impacts of nectar robbing on the foraging ecology of a territorial hummingbird

• Published in: Behavioural processes Vol. 149; pp. 27 - 34
• Main Authors: Hazlehurst, Jenny A., Karubian, Jordan O.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.04.2018; Elsevier Science Ltd
• Subjects: Aglaeactis cupripennis; Animals; Appetitive Behavior - physiology; Birds; Birds - physiology; Diet; Female; Flowers; Flowers & plants; Foraging behavior; Indirect effects; Male; Movement; Mutualism; Nectar; Plant Nectar; Plant-animal mutualism; Plasticity; Pollination; Pollinators; Robbing behavior; Telemetry; Territory; Theft; Movement; Diet; Plant-animal mutualism; Indirect effects; Plasticity; Pollination
• ISSN: 0376-6357; 1872-8308
• DOI: 10.1016/j.beproc.2018.01.001

•This study is among the first to quantify the impacts of nectar robbing from the perspective of pollinators as opposed to plants.•Robbed hummingbirds had a significantly larger territory area than control birds.•Robbed hummingbirds had a significantly different diet than control birds, in which they shifted away from the robbed resource.•Robbed hummingbirds did not show a significant change in the proportion of time spent foraging as compared to all other activities, but did show a decline in foraging relative to territory defense alone.•Hummingbirds demonstrated an adaptive, mixed response in their foraging ecology in response to nectar robbing of their preferred resource. These responses may indicate potential energetic and fitness costs of nectar robbing to pollinators whose preferred resources are robbed. While the effects of nectar robbing on plants are relatively well-studied, its impacts from the perspective of the pollinators of robbed plants is not. Numerous studies do consider the impacts of robbing on pollinator visitation to robbed plants, but rarely do they focus on its scaled-up impacts on individual pollinator behavior. We used radio telemetry to track the spatial and behavioral responses of the territorial hummingbird Aglaeactis cupripennis to experimental nectar robbing over a period of several days. Simulated nectar robbing impacted foraging behavior by increasing territory area, distance flown, and reliance on novel food resources, especially small-bodied flying insects. We did not observe any impact on the amount of time individuals spent foraging, nor did we observe territory abandonment. These findings indicate that nectar robbing may impose a significant energetic cost on pollinators via increased flight distances and shifts towards potentially less profitable food resources, and demonstrate the importance of quantifying the indirect effects of nectar robbing on pollinators in addition to plants.