午夜福利1000集合

IF YOUR holiday plans include a therapeutic session swimming with the
dolphins, there鈥檚 something you should know. Behind that angelic smile lies a
devilish schemer.

Make no mistake, these animals are smart. Only we humans have more brain to
our bulk. And male bottlenoses, at least, choose to direct their superior
intellect to skulduggery. Theirs is a world of sex and violence, where
kidnapping is commonplace and gang warfare rife. Success is all about
cultivating the right friendships and knowing who you can trust when the chips
are down. These guys have a talent for politicking and alliance building that
would shame the Mafia.

Richard Connor and his team from the University of Massachusetts, Dartmouth,
have spent more than a decade watching dolphins in Shark Bay, Western Australia.
They were the first to notice that mature males tend to hang out in pairs or
trios when consorting with females. The bond between such gang members is as
strong as that between a mother and her calves, and stronger than any other
social interaction among members of this 400-strong group. What is going on?

Connor soon realised that these male gangs were after just one thing: sex. A
trio鈥攍et鈥檚 call them the Sharks鈥攚ill kidnap a sexually receptive
female from her normal group and hold her prisoner for a month or more. There is
no gentle courtship. Instead the Sharks herd their trophy around, using brute
force including thumping and biting to keep her moving where they want.
Meanwhile they mate with her, either one at a time or sometimes
simultaneously.

By working together, members of the Sharks can limit the chances of a female
escaping, while each still has a reasonable crack at fatherhood. But things
don鈥檛 always go according to plan. A rival gang鈥攖he Jets, say鈥攎ay
set its sights on this female. The Jets are smart enough not to attack the
Sharks without first making sure they can outnumber the opposition. So they call
in a favour from another gang with whom they regularly form what are called
鈥渟econd-order alliances鈥�. Stealing the female is then a breeze, and the beauty
of this arrangement is that the Jets get to keep the girl, while their allies
swim off knowing that they can call on their friends next time they go out
raiding.

Through watching gang warfare in action, Connor and his team discovered that
alliances within individual gangs are remarkably long-lived, lasting up to 12
years. 鈥淪table alliances really seem to crystallise around sexual maturity,鈥�
says Connor. Each duo or trio then forms second-order alliances with one or two
other gangs鈥攖hough only with one at a time. These coalitions tend to be
more tenuous, generally lasting no more than a few years.

There is no other animal鈥攑oliticians excepted鈥攖hat operates two
levels of male alliances within a single social network. Chimps come closest:
males form strategic alliances within their groups. The whole group also bands
together to fight off rival groups, but this is more a primitive urge to defend
the clan than the complex and strategic behaviour found in dolphins鈥�
second-order alliances.

In fact, Connor has discovered that his Shark Bay dolphins gang up in even
more sophisticated ways. A few years ago, he and his colleagues stumbled across
a dolphin 鈥渟upergang鈥�. This group of 14 males does not have the strong bonding
found within trios or pairs. But by forming a more fluid coalition they seem to
be able to take on all comers. In the three years that the researchers watched
them, they never lost a fight.

Flexible friends

Sheer force of numbers is one obvious advantage of the supergang, bringing
between six and 14 individuals to any fight. But gang members don鈥檛 just cruise
around in one large group. Supergang males still need to form trios to optimise
their chances of fatherhood, but they do not have much loyalty to these smaller
groups. Individuals join between three and seven trios in a single year. Indeed,
the most flexible gang members seem to get the most females. 鈥淚 got the sense
that the core males within the group were the ones who switched partners often,鈥�
says Connor. He thinks that this extreme fluidity of alliances is what holds the
group together. What鈥檚 remarkable, he notes, is that the overall gang membership
did not change during his three years of study.

Explaining why the supergang formed in the first place is a bit trickier.
Connor points out that group living is usually an adaptation to certain types of
habitat. When predators are rife there is safety in numbers, but this benefit
can be outweighed by the difficulty of feeding a large group. However, dolphins
are such efficient swimmers that they can travel away from the group to forage
without expending large amounts of energy.

Still, Connor is surprised that there are no obvious costs to counteract the
benefits of large groups like these. Another surprise is that the home ranges of
the supergang and smaller gangs overlap hugely. So it鈥檚 not differences in
habitat that dictate the different behaviour. This, once again, sets bottlenose
dolphins apart: it is the only example in nature of an animal coming up with two
alternative strategies within a single habitat.

So what makes bottlenose dolphins behave as they do? 鈥淭he complexity we鈥檙e
seeing probably relates to their intelligence,鈥� says Connor. 鈥淭he way they are
brought up may also have a bearing.鈥� Dolphin sociology is in its infancy, but it
seems clear that their brains are not hard-wired to generate this behaviour.
Connor points out that quite different mating strategies are used in two other
well-studied populations. At Sarasota Bay in Florida, males mostly form
pairs, with some singles. Second-order alliances have yet to be discovered. And
in the Moray Firth in Scotland, there are no obvious male gangs at all.

If these guys are so smart, you would expect them to come up with some new
strategies to outwit the supergang. Connor and his team will be on the lookout
for more examples of clever coalitions when they return to Shark Bay next year.
In the meantime, if you find yourself taking a dip with Flipper don鈥檛 be fooled
by his beatific smile.