Group Decision Making in
Honey Bee Swarms
Garrett Barnes and Tom Hickery
Facts about Honey Bees
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Every Bee hive in the late spring or early summer must divide in an act called
swarming
The bees choose a new site and then half leave with the queen and a new
queen is left with the old site.
The optimal conditions of a new site are:
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Cavity greater that 20 liters
Entrance hole
■ smaller than 30 square cm
■ Facing south
■ At the bottom of the cavity
Worker piping - scout bees warm up waiting members to get ready to depart.
Bee Dancing
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Lindaur in the 1950’s discovered that the ‘waggle dance’ previously known to
help recruit foragers was also used in nest selection
The Bees uses two components to tell the location of the possible site
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Angle
Length of waggle run.
Consensus
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Consensus was the way that
vs
Quorum
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people believed bees decided.
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The thought was all bees okayed
New theory of how bees reach
the decision of the new site.
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Number of bees must reach a
the new site
certain threshold and then the
While it was possible, there were
bees depart.
documented cases of bees not
waiting for consensus
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Works most of the time but a few
outlying cases cause issues.
Bees find potential locations for new hives by
sending out scouts.
The scouts return, communicating the location of the site through dance.
Bees also communicate the quality of a location with the number of dance circuits.
More dance circuits means a better location.
The scouts generally make multiple trips, sending back a weaker “signal” each
time until they abandon their potential site and start looking for another one.
The signals for low-quality sites deteriorate quickly, causing them to be
abandoned faster than high-quality sites.
Bees ‘vote’ by visiting the site they prefer.
Once ~15 bees are in a location at the same time, the hive starts preparing to
relocate there.
When bees discover the ‘best’ site, they stop going to other sites and start going
there, helping the hive reach quorum.
Experiments
Speed Versus Accuracy
Choosing quickly lets hives expand quickly, but deliberating allows them to make
better choices.
The speed of the decision can be changed by changing the number of bees
required to reach quorum.
Computer models find that the best trade-off between speed and accuracy is 1520 bees - very close to the actual number!