Prairie dogs disperse when all close kin have disappeared

Because competition decreases inclusive fitness among kin, Hamilton and May predicted that the presence of nearby kin should induce the dispersal of individuals from the natal territory, independent of pressures to avoid inbreeding. Many studies support this landmark prediction, but research over 31 years with prairie dogs reveals the opposite pattern: Young females are 12.5 times more likely to disperse in the absence of mother and siblings for one species, and 5.5 times more likely for another species. Such striking patterns probably occur because cooperation among kin is more important than competition among kin for young prairie dogs. The inability to cooperate with close kin, due to their absence, prompts a search for a new territory where cooperation might be less crucial for survival and reproduction.