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Bees feed almost exclusively on nectar and pollen from flowers. However, little is known about how food availability limits bee populations. To gain insights into the potential for food limitation within subalpine bumble bee populations, I examined bee foraging distances and the relationship between forager and flower densities. If floral resources are limited, then bees should fly farther to forage, and they should be more abundant in areas with more flowers. I estimated foraging distances by calculating forager recapture probabilities at increasing distances (up to 3,766 m) from eight marking locations, and I measured natural variation in forager and flower densities for 11 weeks in six half- hectare plots. Because flower availability should be lowest late in the season when bee density is high relative to flower density, I predicted that late in the season I would: (1) recapture foragers at farther distances and (2) find stronger relationships between forager and flower densities. These predictions were not upheld. Throughout the flowering season, I primarily found marked bees only within 100 m (and never over 1,000 m) from their original marking location, suggesting that they typically did not fly far to forage. Although the density of early season foragers (mostly founding queens) increased with early-season flower density, the density of mid- and late-season foragers (mostly workers and males) did not vary with flower density. In addition, forager densities later in the flowering season were not related to earlier bee or flower densities, suggesting that there were no delayed effects of floral resources or colony productivity on forager density. These results suggest that these high elevation bumble bees may have ample floral resources for reproduction, a hypothesis that warrants further experimental investigation. 20
Knowledge graph centered on Reciprocal benefits in a plant-pollinator mutualis with 66 nodes and 128 connections. Top connected: Two-form Bumble Bee, Bumble Bees, Yellow-fronted Bumble Bee, Buff-tailed Bumble Bee, Common Eastern Bumble Bee.
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18 in Knowledge Commons, 197 external