Biology Reference
In-Depth Information
Fig. 6.14
A pack
of fourteen
spotted hyenas
hunting a group
of zebras. The
zebra mares and
foals run in a tight
formation,
followed by the
stallion, who
repeatedly
charges at the
hyenas. From
Kruuk (1972).
walked or ran in a tight bunch and the hyenas usually followed in a crescent formation
behind, attempting to bite any zebra on the edge of the group, while dodging its defensive
kicks (Fig. 6.14). The chase lasted for up to 3 km, by which time the hyenas often had
singled out one zebra that had fallen behind, either because it was in poorer condition
or because one hyena had managed to get a grip on it. All the other hyenas would then
immediately concentrate on this one zebra and help to pull it down.
Lions,
Panthera leo
, also benefit from hunting in groups when tackling large prey, such
as buffalo, which are difficult for one lion to kill alone, or when making surprise attacks
on prey which can outrun them (Fig. 6.13b). Philip Stander (1992) studied lions in
Etosha National Park, Namibia, where the main prey were zebra, springbok (
Antidorcas
marsupialis
) and wildebeest (
Connochaetes taurinus
). He could recognize individual
lionesses by brand marks and some were radio-collared, so he could track the group
during a hunt. He found remarkable individual specializations, rather like those of a
football team. The pride usually adopted a formation where some lionesses ('wings')
circled the prey while others ('centres') waited in hiding. Individuals tended to specialize
as either left or right wings or centres (Fig. 6.15). The wings tended to stalk the prey and
initiate the attack, while the centres, which were usually the largest and heaviest
lionesses in the group, most often made the kill as the prey was driven towards them. Not
only did individual lionesses have regular positions in the hunting formation, but hunts
were also more successful when most lionesses were playing in their preferred positions.
Not all hunting groups have this level of sophistication. Often a group is more
successful simply because the simultaneous attack by many predators is more effective
in causing panic in the prey, and as they flee in all directions the predators can more
easily pick them off, one by one. This applies for example, to black-headed gulls (
Larus
ridibundus
) and jack (a predatory fish,
Caranx ignobilis
), where an individual's hunting
success against shoals of small fish prey increases with the number of predators in the
hunting group (Götmark
et al
., 1986; Major, 1978).
Individual
lionesses may
favour particular
positions in a
group hunt
