Socialites unite dolphin groups

ABERDEEN, Scotland, 12 August, 2004 - Dolphin groups, or "pods" rely
on socialites to keep them together, scientists have claimed.

Without these individuals, the cohesion of the dolphin group falls
apart, researchers have discovered.

The finding may mean that capturing wild dolphins or killer whales for
marine parks could have a serious impact on their companions left behind.

Details of the study, by a UK and US research team, are outlined in
New Scientist magazine.

Ecologist David Lusseau, from the University of Aberdeen, UK, studied
the social interctions of a community of 62 bottlenose dolphins living
in Doubtful Sound, New Zealand.

Chance encounters?

From 1994 to 2001, he tracked individual animals and worked out which
ones appeared together more often than would be expected by chance.

His colleague, Mark Newman from the University of Michigan in Ann
Arbor, US, then applied a mathematical technique used for probing
complex networks.

What emerged were two sizeable sub-communities joined together
tenuously by just a few common members.

These dolphins occupied central roles in the social network. But
without them, the entire network was likely to split into two.

"Remarkably this is exactly what happened," Newman told New Scientist
magazine. "Some years into the study, two of these keystone
individuals did indeed disappear, and the community split into two
separate groups that went their own way."

When the missing individuals returned, the pod re-formed.

The results of the study are to be published in a future issue of the
Royal Society journal Biology Letters.

http://news.bbc.co.uk/1/hi/sci/tech/3558994.stm

© 2004. BBC. All rights reserved.