UBC Theses and Dissertations
Dynamics of hummingbird mediated pollen flow in a subalpine meadow Perkins, Mary Dee Chynoweth
Previous authors have concluded that hummingbird territorial boundaries would restrict pollen flow. I questioned the validity of this on the time scale of a blooming season for a system in which individual plants remained in flower while the territories surrounding them often changed in size and shape. To determine the effects of hummingbird foraging behavior on pollen flow, I studied six components of a hummingbird-plant pollination system: hummingbird territorial behavior, plant blooming time, foraging flight distances, pollen carry over, other pollinators, and plant breeding systems. Using this information I found I could depict pollen flow between two plants as a function of: 1) The flowering times of the plants. 2) The distance between the plants. 3) The amount of time these plants are surrounded by the same territorial boundaries. 4) The number of plants (or flowers) the bird visits before visiting the second plant. I found that the influence of territorial boundaries on pollen flow is determined not by the boundary of a single territory, but by the influence of all the territorial boundaries surrounding a plant while it is in bloom. Within these boundaries, the probability of pollen being transfered between two plants is a function of the amount of time they are within the same boundary. The length of hummingbird foraging flights is also a major determinant of pollen flow and the predominance of short flights between plants may restrict pollen flow probabilities. The restriction imposed by these short flights may be reduced by 1) long pollen carry over distances and 2) the longer flight distances between a perch and a plant.
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