Do males know? Evidence-driven rainmaking of male bonobos to meet fertile phase of females

Female bonobos exhibit prolonged receptivity. One suggested function of the prolonged receptivity is it lowers male mating competition. However, it is questionable whether easier access to receptive females can reduce male-male competition, given the exclusive nature of male reproductive success. We tested whether males could determine a fertile phase of females. We found that daily ovulation probability predicted male mating effort. High-ranking males copulated with the female with higher fertility, and they also engaged in agonistic interactions more often when there were fertile females in the group. When several females with maximal swelling existed, males concentrated mating effort to a female with older dependent offspring, whose maximal swelling phase started earlier and keep mating efforts until detumescence (rainmaking). These results suggest that male bonobos can discriminate the fertile phase of females, and male-male competition over females is also an important mating strategy to increases access to fertile females in bonobos. ### Competing Interest Statement The authors have declared no competing interest.