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Members who live in groups must be in the same place at the same time, which calls for a degree of synchrony (Conradt&Roper 2000). It is costly for an organism to coordinate activities with a group because he may be forced to give up his optimal habits to synchronize with the group. This cost affects the decision of an individual to remain in a group, impacting group stability, composition, and organization. This is why often individuals are found in groups of similar individuals based on age, sex, or size (Conradt&Roper 2000). Individuals choose group living and alliance formation when benefits outweigh costs.
Males use herding to isolate a female, culminating in fertilization. However, herding is only successful if the male mates with the female when she is most likely to conceive (Connor et al. 1996). Males exhibit aggressive behavior when trying to accost a female. If a male is interested in a female, he will make a distinct popping sound to get the female’s attention. It has been shown that popping induces females to turn toward males because females may associate popping with male aggression. Often, if the female does not respond to male popping, the male will attack her (Connor&Smolker 1996). In addition, males perform aggressive head jerks while popping. The popping noise is of a lower frequency than the usual high-pitched vocalizations because sounds of lower frequencies are less directionally oriented, so the female can hear the noise even if the male is not facing her (Connor&Smolker 1996). Once a male has the female’s attention, he and his alliance cooperatively display to the female, engaging in synchronized underwater turns, aerial leaps, and flips (Connor 1992). If the female again does not respond or tries to swim away, the males aggressively chase her, slap with their tails, bite her, charge at her, and even body-slam her (Connor 1992). During a chase, males swim in formation, flanking her from each side to effectively cut her off. In 1992, Connor et al. observed that out of 179 courtships observed, only 45 females tried to escape (25%) and males chased 25 out of the 45 attempted escapes (45%). Female choice may be playing a part with the displays of males. If the female tries to escape from the male, she increases the probability that she will mate with the fittest male because the quickest male will be the one who catches up with her (Connor et al. 1996).
Interactions between male primates are similar to alliance interactions in male bottlenose dolphins in that both primates and bottlenose dolphins associate nonagonistically and agonistically, may become allies with past agonists, and use alliances to aggressively consort females (Connor et al. 1992). In chimpanzees, females mate with multiple males, so males may use alliance formation as a strategy to monopolize females. In a study by Nishida, a society of wild chimpanzees was observed to study the formation of alliances and distribution of paternity (1983). In this society, alliances were formed between three males, alpha, beta, and gamma. The alpha male fathered the most offspring, followed by beta, then gamma. However, the gamma male, although the male with least paternities, played a pivotal role in the alliance dynamics. It was observed that sometimes the gamma male would side with the alpha male and sometimes with the beta male. When the beta and gamma male joined against the alpha male, he lost his paternity advantage. This ability to tip the scales gives the gamma male the ability to manipulate alliance interactions ( triadic interactions ) (Nishida 1983).
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