“…Coalitions can occur opportunistically on a case-by-case basis (e.g., Bissonnette, 2009;Smith et al, 2010), or they can be observed frequently among the same partners as part of an enduring, long-term relationship (e.g., de Waal, 1982;Packer & Pusey, 1982;Smuts, 1985;Goodall, 1986;Noë, 1986b;Caro & Collins, 1987;Connor et al, 1992Connor et al, , 2001Feh, 1999;Boesch & BoeschAchermann, 2000;Boinski et al, 2005;Schülke et al, 2010). One individual may establish year-long, stable alliances with one or a few partners and also participate in opportunistic coalitions with other group members in which loyalties change regularly (Riss & Goodall, 1977;de Waal, 1982;Goodall, 1986;Noë, 1990;Uehara et al, 1994;Connor et al, 2000;Sijtsema et al, 2010). For example, Nishida (1983) and de Waal (1984) have argued that male chimpanzees intervene opportunistically in 'political' conflicts and may turn against former allies when it is beneficial to do so.…”