Pack hunter
[4] Most pack hunters are found in the southern African savannas, with a notable absence in tropical rainforests and with the exception of the wolf and coyote, higher latitudes.
[4] It is thought that either on the ancient and poor soils of the southern African savanna it is not possible for individual predators to find adequate food,[5] or that the environment's inherent unpredictability due to ENSO or IOD events means that in very bad conditions it will not be possible to raise the young necessary to prevent declining populations from adult mortality.
It is also argued that Africa's large area of continuous flat and open country, which was even more extensive while rainforest contracted during glacial periods of the Quaternary, may have helped encourage pack hunting to become much more common than on any other continent.
The proportion of these strategies increases in larger groups, since only a certain number of individuals are required to help make the kill, allowing others to directly benefit without participating in the hunt.
The model predicts that the only way cooperative hunting is an ESS for single small prey is if the predators are already constrained to live in groups—so they must share what they get in order to keep the group stable.
[14] In 1994, Christophe Boesch condensed Packer and Ruttan's model to two basic conditions and added a crucial third component based on his study of chimpanzees (Pan troglodytes) in the Taï National Park of Côte d'Ivoire: Curiously, among female Taï chimpanzees, cheating has become an ESS because there are substantially more costs associated with hunting, including the risk of dropping infants from trees and injuring them.
The results above suggest that social living in chimps may not be a necessary prerequisite for the evolution of cooperative hunting; instead, the distribution of resources is a critical determining factor.
Consequentially, cooperative hunting most likely evolved in areas with scarce prey distribution, and patterns of this behavior are likely to vary with seasonal fluctuation of available resources.
There are two main goals to cooperative hunting in social carnivores: taking down large prey species through a coordinated effort and subsequently protecting their kill from scavengers.
[9] A common goal in cooperatively hunting pairs is to coordinate the separation of a mother and her offspring, facilitating an easier kill that a solitary hunter could not make.
Higher success in prey capture has been demonstrated in wild dogs,[8] bottlenose dolphins, and other cetaceans,[18] falcons, and fossa due to cooperative hunting.
[12] As a result, the high overall success rate of cooperative hunting leads to higher per capita meat intake even in large groups.
This research successfully demonstrates that varying ecological variables are responsible for the difference in optimum group size among cooperatively hunting animals.
A wolf pack may trail a herd of elk, caribou or other large prey for days, looking for an animal that displays any sign of weakness, before making its move.
Speedy, lightly built females often take on herding roles, darting back and forth in front of prey, causing confusion and preventing escape.
Stefanie Gazda and colleagues predict that this role specialization is more common in marine than terrestrial animals due to a higher variability in prey diversity, biomass, and predator mobility in the ocean.
Cooperative hunting strategy in lions is based on groups of three to seven individuals split into two highly specialized roles, centers and wings, which coordinate their movement to encircle and ambush the prey.
As the wings slowly encircle their mark, they drive the prey towards the waiting center—often one of the older and heavier individuals in the group—who then pounces to make the kill.
Blocking and ambushing are thought to require much more cognitive effort in anticipating the future movements of the prey, and they are thus rewarded with a larger proportion of meat after a successful hunt.
Alvard echoes other research by suggesting that these shared norms of meat distribution sustains cooperative hunting and prevents the rise of cheaters.
Research conducted by Vladmir Dinets has indicated that crocodilians regularly engage in cooperative hunting behavior, including highly organized game drives.
Behaviours noted by Dinets include forming tight "bait balls" when hunting fish and being able to anticipate the location and actions of other crocodiles without being able to see them for an ambush.
[26] Groupers (Plectropomus pessuliferus marisrubri) and giant moray eels (Gymnothorax javanicus) provide compelling evidence for interspecific cooperative hunting.
[1][27] Cooperative hunting is sometimes thought to reflect advanced cognitive processes, such as foresight, planning, and theory of mind[28] and involve complex communication between hunters.
[29] However, several lines of evidence indicate that many instances of cooperative hunting rely on simple principles[30] and can be observed in species without large brains or advanced cognitive abilities.
[32] In addition, frequent and successful pack hunting may depend on a higher level of social harmony, complexity, or intelligence, which may facilitate concerted group activities.
To differentiate between different levels of cooperative hunting, Boesch & Boesch[32] developed a scheme for categorizing group hunts: A variety of social carnivores, such as wolves, lions, and African wild dogs have been observed to operate at the level of coordination and occasionally collaboration,[28] while some populations of chimps have been observed to collaborate frequently with several distinct roles.
[41] They concluded that "elaborate coordination can be achieved through a relatively simple decision process of mapping between observations and actions via distance-dependent internal representations formed by prior experience."
However, Boesch counters this by pointing out that Taï chimps fulfill all the hallmarks of shared intentionality,[43] bringing into question either the uniqueness or the complexity of this cognitive process.
[28] A harmonious pack structure may allow for the emergence of more frequent cooperative hunts, as group activities and food sharing are facilitated by lower levels of aggression and fear.
