In cooperative breeders, sexually mature subordinates can either queue for chances to inherit the breeding position in their natal group, or disperse to reproduce independently. The choice of one or the other option may be flexible, as when individuals respond to attractive dispersal options, or they may reflect fixed life-history trajectories. Here, we show in a permanently marked, natural population of the cooperatively breeding cichlid fish Neolamprologus pulcher that subordinate helpers reduce investment in territory defence shortly before dispersing. Such reduction of effort is not shown by subordinates who stay and inherit the breeding position. This difference suggests that subordinates ready to leave reduce their investment in the natal territory strategically in favour of future life-history perspectives. It seems to be part of a conditional choice of the dispersal tactic, as this reduction in effort appears only shortly before dispersal, whereas philopatric and dispersing helpers do not differ in defence effort earlier in life. Hence, cooperative territory defence is state-dependent and plastic rather than a consistent part of a fixed life-history trajectory.

Long term data from 2009ID= individual, Disperser: 0=heir 1=disperser, agg_gm= frequency of agression against group members, agg_ngm= frequency of agression against non-group members, sub_gm= frequency of submission, pred_def= frequency of defence against predators, dig_tot= frequency of territory maintenance; each line represents a case2009data_forpub_final.txt2010 data.Short term behavioural changes. ID= Individaul identifier, observer_cap= person who captured individual, before= timing of the observation (before or after takeover), disperser: 0=heir, 1=disperser, pred_def_foc= Frequency of territory defence, sub_grp_mem= Frequency of sumbission, tot_dig=frequency of territory maintenence, log_tot_dig= natural log of "tot_dig", agg_strangers= frequency of territory defence against non group members2010data_forpub_final.txt