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Cooperative Hunting

Cooperation typically refers to an outcome in which two or more interacting individuals each receives a net benefit from their joint actions, despite the costs they may have to pay for undertaking such actions. Cooperation in hunting has many advantages to different species with all different behavioral patterns. Cooperation behavior can be found in the range of animals from all over the world, from Northern Shrikes in Alaska, to the Northern Grey Wolf in North America, to the Afircan Wild Dog

The species Canis Lupus is spread throughout the world in different enviornments. The species has adapted to their enviornments and used cooperative behavior and hunting to survive. The Northern Gray wolves, the largest species of the Canis, use cooperative behavior the most to their benefit. They live in social units, or packs, to take care of young, to defend territory, and to hunt for food. Packs are divided into two different sectors, hierarchial packs which is the wolves immediate family, and also larger packs which are the combination of two or more hierarchial packs. The packs cooperates to hunt together using different methods. Studies have shown two different methods, encircling and relay hunting. Encircling refers to two or more wolves move togther in one direction, while two or more move in another to keep the prey moving back and forth until it is in the middle of the pack trapped. The other method is relay hunting. Relay hunting is similiar to an actual relay race, one wolf hunts down the prey and brings it towards another wolf of its pack, once the prey reaches the next wolf the first can take a break as the other chases. Cooperative hunting is a behavior rarely observed in passerine birds. I observed two immature northern shrikes apparently hunting cooperatively while preying on American Tree Sparrows in central Alaska. During each of three foraging attempts, both shrikes appeared to work together to flush prey from dense cover into the open where it was then pursued. Cooperative hunting in this otherwise solitary species may be an adaptive behavior among inexperienced birds to increase their foraging efficiency, or to compensate for seasonal fluctuations in the accessibility or availability of prey. Hannah observes the Shrikes (Lanius excubitor invictus) working together flushing an American tree sparrow from dense thicket with a systematic approach. After reading what Hannah observed I find the Northern Shrikes to have very similar approach to cooperative hunting as a pack of wolves. The first Northern Shrike will draw its prey towards its partner for it to hunt the prey. Both birds work together to hunt their prey.

The Ethiopian Wolf (Canis simensis) is a rare and endangered carnivore found in a few mountain ranges in the Ethiopian Highlands. The wolf is a medium sized social canid (16kg's). The wolfs habitat consists of short grass which support a high bio mass of small mammals. During early studies in 1945 they were noted for hunting in small packs killing sheep and small game. As time and environment and landscaped changed they now mainly hunt small rodents and often forage alone. The size of the prey dictates how they hunt to feed themselves. The main focal part of the study was to collect data on what they eat. The study was concluded by collecting the animals droppings. The Ethiopian wolf is a specialist rodent eater, adapted to prey upon the dense population of diurnal rodents present in Afro Alpine grasslands. Although the wolf has mastered solo killing the rodents they often convert back to pack scavenging with strength in numbers to eat from carcasses when available before being chased off from larger predators. Studies have shown they're caught more frequently when baited with a sheep or cow rather than rodents. Their diet has been adapted to better suit their changing environment.

The African Wild dogs are one of the most social candids, forming 2-50 animals in a pack. There is a direct correlation with the size of the pack as well as the size of gazelle or wildebeest packs that are hunted down. As the pack increases so does the chance at a successful hunt, a long with the size of the prey. In areas where hyenas a present lower numbers in the pack make it very hard to maintain to a kill. In situations where 1-2 does are present hyenas sometimes succeeded at stealing the kill almost as soon as the dog was beginning to feed. The length of time for which dogs fed also depended on the relative numbers of hyenas and dogs, being longer when the ratio of dogs to hyena was high (correlation between delay and dog/hyena ratio= 0-63, N=53,r2=0-39, P<0-01). Thus, even large groups lost control of carcasses relatively quickly if hyenas were particularly numerous around a kill site.

Studies investigating the effects of snow on predatory behavior of wolves show that the deeper snow generally increases hunting success and kill rate. The moose are vulnerable to predation of wolves at greater snow depths. Sometimes the ages effect the individual or pack hunting a long lived species of a wolf becomes a more experience hunter with age. It's similar to the African Dog that the success rate and size of prey will depend on the size of the pack. Smaller packs virtually forced to hunt calves and deer compared to a full grown moose.

Although they are a related species The Ethiopian Wolf and the Northern Grey wolf have differences. The vast majority of the Ethiopians prey is small, so they rely on their own hunting skills rather than the packs, while the Grey wolf is able to hunt down a moose which can feed the entire pack.

In a different species, The Northern Shrike, the birds cooperatively work together to kill the sparrow, but only one shrike captured the sparrow and flew to a perch to eat leaving the other Shrike out of its meal. The one who was left out used a lot of energy for no reward, which is the case when cooperative hunting is not beneficial. But at the same time when they hunt together sometimes the inexperienced bird can end up with the prey as the experienced bird flushes the prey.