If the territory shrinks, the number of contacts increases and the ant alters its search pattern. If it expands, contact decreases and it alters the pattern a different way.
In the Arizona harvester ants, Gordon studies tasks besides patrolling. Each ant has a job.
I divide the tasks into four: foraging, nest maintenance, midden and patrolling - patrollers are the ones that come out first in the morning and look for food. The foragers go where the patrollers find food.
The colony has about eight different foraging paths. Every day it uses several of them. The patrollers go out first on the trails and they attract each other when they find food. By the end of an hours patrolling, most patrollers are on just a few trails. . . . All the foragers have to do is go where there are the most patrollers.
Each ant has its prescribed task, but the ants can switch tasks if the collective needs it. An ant on housekeeping duty will decide to forage. No one told it to do so and Gordon and other entomologists dont know how that happens.
No ant can possibly know how much food everybody is collecting, how many foragers are needed, she said. An ant has to have very simple rules that tell it, OK, switch and start foraging. But an ant cant assess globally how much food the colony needs.
39;ve done perturbation experiments in which I marked ants according to what task theyre doing on a given day. The ants that were foraging for food were green, those that were cleaning the nest were blue and so on. Then I created some new situation in the environment; for example, I create a mess that the nest maintenance workers have to clean up or Ill put out extra food that attracts more foragers.
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