THE CO-OPERATING HUNTERS

Kristin Barsett Magnus
veterinary student, first year

In nature many animals choose to live side by side with other members of their species, interconnecting in smaller or larger groups. The animal's group-pattern reflects normally important environmental problems that affect their ability to survive and reform within a given habitat. We can think of three causes why life in groups are preferred by so many wild animal species, although not more than one of them needs to be of importance in each single case. First of all, groups can make it easier for animals to avoid attack from enemies. (E.g. by warning each other of the danger ahead.) A second great advantage of living together is that it secures and makes the care for the children more efficient. And the last cause is to give the single animal a greater and better chance to find food.

I will now take a closer look at the third cause, and try to describe the predator's advantages of living and hunting together.

Many big carnivores live within groups. Wolves keep together in family arrangements that consist of one breeding pair, (Alfa male + Alfa female), subordinate animals and juveniles. During the winter, wolf packs are big, up to 30 animals. But in summertime, with greater access of small mammals, the pack often breaks up into smaller groups.

African wild dogs and hyenas live within great groups with up to 80 individuals. By hunting together these animals can catch a prey much bigger than themselves. For example wolves can bring down a moose, although these animals are several times bigger than the wolves. (An adult male can have a shoulder height at 230 cm, and weight up to 800 kg.)

The hunting success for all preys increase according to the size of the group of hunters. Single lions succeed in about 15% of their attempts of catching a prey. Compered to this, the number increases to a maximum of 33% for groups that consist of six or more lions. The difference is mostly seen for bigger preys like for example zebra. For this species, groups of lions with more than six members succeed in 43% of their trials. (The tiger hunts alone, and only seldom do they catch the prey in more than 8% of their trials..)

Groups of predators have greater success during hunting because they can co-operate their movements, and thus prevent the prey from escaping. The lonely predator has to follow every movements, swings and jumps of the prey's run. This often ends with the predator loosing contact when the prey suddenly changes direction or seeks cover in the vegetation. Hunters that work together can post a guard that leads the animal to the most aggressive hunters. 

Some carnivores use the technique of "hunting by shifts". Wolves and wild dogs pick out and pursue preys as a group, but only one of them carry out the active persuasion. The other individuals of the pack trot along behind in a lower speed, spearing energy by guessing the escape route of the prey, and inhibit it. When the actively hunting animal gets tired, it falls back, and another, more rested animal replaces it.

African wild dogs (Lycaon pictus) use this method when hunting. With their nose low, to be able to follow the track, they pursue a prey till it collapses of exhaustion. The wild dog is not a very fast runner, but is on the other hand more enduring. With alternately resting and hunting, a group can bring down a prey as big as a zebra. Lycaon pictus kills by disembowelling.

 Adult wild dogs, with round saucer-like ears and a "painted" black, white, brown, and yellow coat, weigh up to 55 pounds (25 kilograms) and stand about 2 feet tall (60 centimetres) with the delicate build of a greyhound.

Wild dogs are intensely social animals, the entire pack—sometimes up to 20 dogs—always hunts, plays, walks, and feeds together. They never leave an animal behind and are always reinforcing social bonds.

Each pack has only one breeding pair, and the rest of the pack helps raise the annual litter—up to 20 pups, one of the largest litter sizes of all carnivores. Wild dogs are tough to track. These nomads travel up to 20 miles (30 kilometres) daily, with vast home ranges, 200 to 300 square miles (600 to 800 square kilometres) on average.

  The African wild dog, Lycaon pictus, also called the painted wolf or the Cape hunting dog is the victim mainly of human persecution. The dog is listed as endangered by the World Conservation Union (IUCN). Lycaon pictus once roamed most of sub-Saharan Africa. Now only about 5,000 dogs can be found in isolated pockets

A sheepdog's ability to organise a sheepflock, is a direct survival of their wolf-ancestor's group hunting. When a pack of wolves hunts reindeer, it tries to force the prey into a bounded area, (for example a spinney or a grove). One of the wolves then moves to a place in front of the prey, while the others leads it into the trap. A sheepdog uses the same tactic. It acts according to the shepherd's instructions, and walk around to the opposite side of the flock. Here it can, together with the shepherd, lead the flock towards an enclosure / fencing.

Sources:

www.nationalgeographic.com

And

A Norwegian book: "Dyrenes Verden" directly translated; "Animals World"