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Thesis Abstract – Capell (1992)


Colony-Level Optimal Foraging in the Harvester Ant, Pogonomyrmex californicus: Does Recruitment Behavior Have an Associated Cost?

Author and college:

Warren Capell, Pomona College


May 1, 1992


Bachelor of Arts in Biology


Paulette Bierzychudek, Pomona College


Optimal foraging theories have been extremely useful to behavioral ecologists in predicting how an individually foraging organism will behave; however, the theories do not consider the capabilities of complex superorganisms, such as social insect colonies, which have independently moving units, but which behave as a single organism. The mobilization and allocation of workers to food patches in harvester ants is accomplished through chemical recruitment. While recruitment behavior is clearly advantageous to a colony, it may also have an associated cost; a colony which is foraging at a food patch may temporarily suspend efforts to search the environment for other, potentially more profitable, food patches. A failure to control the food sites in a colony’s environment could constitute a significant loss of potential resources to the colony but so far this possible cost has not been explored. In this research, food sources were presented to a colony of harvester ants, Pogonomyrmex californicus, under different conditions in order to assess whether the commitment of recruiting to a specific food patch has an adverse effect on either the colony’s discovery time or foraging buildup at a new food source introduced into the environment. The results were ambiguous and seem to have been obscured by both a patch-position bias and a specific satiation-type effect; nevertheless, there is some evidence that a cost of recruitment may exist with respect to the foraging buildup at a new food site. Limitations of the optimal foraging models, as applied to superorganisms, are also discussed.

For more information:

Contact Gail Sundberg – gail.sundberg@pomona.edu

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