Rewiring
their social networks is something that has been going on with bottlenose
dolphins in Moreton Bay on the Queensland coast of Australia. This is not due
to a recent love fest, but is the result of enlightened self-interest.
Ansmann et
al’s study followed the two groups that coexisted in Moreton Bay
steadfastly ignoring each other for years (1, 2). The smaller group kept doing
the usual dolphin thing of hunting fish in little flexible sub-groups of the
network. But the larger group members were kicking back, taking it easy in a tight
network waiting for the shrimp trawlers to give them a free handout of bycatch.
Free
lunches don’t last forever and when a ban on trawling was imposed, times had to
change. Hunting isa collaborative activity and the two networks are now
interacting with intergroup network nodes.
No
danger of bycatch looked like good news for the prey fish, but with the
networks merging to gain efficiencies of scale in hunting, they will wipe out that
gain. I guess it's the usual thing if you are well down the food chain – your
screwed if they do and you’re screwed if they don’t.
It will be interesting to see how the new
network develops and see if it grows organically by other dolphins signing up,
or whether other smaller networks will drift into range and get subsumed into
the growing giant.
- I.C. Ansmann et al, J. Animal Behaviour, 2012, http://dx.doi.org/10.1016/j.anbehav.2012.06.009
- www.bbc.co.uk/nature/18985101
