Animal cooperation in the wild often involves multiple individuals that must tolerate each other in close proximity. However, most cooperation experiments in the lab are done with two animals, that are often also physically separated. Such experiments are useful for answering some pertinent questions, for example about the understanding of the role of the partner and strategies of partner control, but say little about factors determining successful cooperation with multiple partners in group settings. We explored the influence of dominance, rank distance, tolerance, affiliation, and coordination by testing kea parrots with a box requiring two, three, or four chains to be pulled simultaneously to access food rewards. The reward could be divided unevenly, but not monopolized completely. Eventually dyadic, triadic, and tetradic cooperation tasks were solved, showing that non-human animals are capable of tetradic cooperation in an experimental setup. Starting with two chains, we found that in a dyad monopolization of the box by the highest-ranking bird was the largest obstacle preventing successful cooperation. High-ranking birds learned to restrain themselves from monopolizing the box during a single session in which monopolization was hindered by the presence of a large number of birds. Thereafter, restraint by dominants remained the strongest factor determining success in the first trial in dyadic, triadic, and tetradic setups. The probability of success increased with the degree of restraint shown by all dominant subjects present. Previous experience with the task contributed to success in subsequent sessions, while increasing rank distance reduced success notably in the four-chain setup.

在野外的动物合作通常涉及多个个体，这些个体必须彼此紧邻。但是，实验室中的大多数合作实验都是对两只动物进行的，它们通常也是物理上分开的。这样的实验对于回答一些相关的问题很有用，例如，关于对伙伴角色的理解和伙伴控制策略的了解，但是对于决定与小组中的多个伙伴成功合作的因素却谈得很少。我们通过使用需要同时拉动两个，三个或四个链条以获取食物奖励的盒子测试kea鹦鹉，探索了统治力，等级距离，宽容，隶属关系和协调性的影响。奖励可能分配不均，但不能完全垄断。最终是二元的，三元的 解决了四方合作的任务，表明非人类动物能够在实验装置中进行四方合作。从两条链条开始，我们发现在最高等级的鸟类对盒的双重垄断中，这是阻碍成功合作的最大障碍。高级别的鸟类学会了在一个单一的时段内限制自己垄断盒子，在这种情况下，大量鸟类的存在阻碍了垄断。此后，在二进，三合和四分法设置的第一次试验中，主导者的约束仍然是决定是否成功的最重要因素。成功的可能性随着在场所有主要受试者表现出的克制程度而增加。以前的工作经验有助于以后的会议取得成功，