Patchiness in the dispersion of nectar resources: Evidence for hot and cold spots.

The dispersion pattern of resources can have a significant effect on foraging behavior. We examined the dispersion pattern of standing crop of nectar in a population of Delphinium nelsonii. The nectar content of flowers was measured for subject inflorescences and their two nearest neighbors. Inflorescences were divided into those which had some nectar (hot plants) and those which had none (cold plants). Tests for independence showed that subject plants and their neighbors were likely to have the same "temperature", indicating that resources were patchy. The implications of this pattern for the foraging movements of bumblebees are discussed.