Social species, from us to
ants, band together for the general good. In many ways we don’t seem to be as
efficient at social behavior as ants, though. Perhaps we think too much. But we
do have the advantage that we can study ants rather than vice versa, as they
seem too busy being social.
An occupation that consumes
a lot of effort in all social groups is in defending their territory. We know
that there is a home field advantage, but if we remove that and other
advantages, which group would win? Batchelor et al decided to seek an answer to that question by studying groups
of Formica rufa (wood ants) set up
for a good set to (1).
The gladiatorial arena was
set up with ptfe plastic sides so there was no escape. A ptfe plastic barrier
separated opposing groups until the starting whistle blew. We should note that
the groups had some of their nesting material tossed in to make them feel at
home so they would both be defending their home patch and not just think that
they’d got lost and bumped into some ruffians.
Small, medium and large
size gladiators were selected for the affray and, in place of uniforms,
opponents were painted yellow or blue so the spectators could tell on whom to
place their bets and then see who won. A variety of group contests were set up
with large group versus large or small group with variation in combatant sizes
to give a tourney of nine separate contests.
The conclusions were that
the aggressiveness of the group increased with size of the individuals in the group.
The big individuals were most aggressive against smaller opponents and the
attrition rate of the small ants was higher than that of the big ones.
With equal composition
groups, even odds were the best you could get. Smaller groups with a large
number of big members could defeat a larger group with fewer large members.
Interestingly, medium sized F. rufas were more aggressive towards large F.
rufans than smaller ones. I guess they knew the David and Goliath story.
In summary, the fighting
ability of the group resulted from the sum of the fighting ability of the
individuals, so it was very much a team effort and relying on champions didn’t
work out.
I should mention that these
contests were not mere quick skirmishes, although a snapshot of the state of
play was taken at thirty minutes, they went on for a full 24 hours before the final
score of the dead and dying of each side was counted to determine the winner.
- T.P Batchelor, G. Santini and M. Briffa, Animal Behaviour, 83, 111, (2011).
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