Gens (behaviour)
In animal behaviour, a gens (pl. gentes) or host race is a host-specific lineage of a brood parasite species. Brood parasites such as cuckoos, which use multiple host species to raise their chicks, evolve different gentes, each one specific to its host species. This specialisation allows the parasites to lay eggs that mimic those of their hosts, which in turn reduces the chances of the eggs being rejected by the hosts.