Offspring sex ratio in a communal breeding bird is male-biased when pre-breeding rainfall is low
Offspring sex ratios may deviate from parity when the fitness benefits of producing male or female offspring vary. We tested for sex ratio bias in smooth-billed anis Crotophaga ani, a communal laying cuckoo with low within-group relatedness and high offspring dispersal. One male group member performs nocturnal incubation and sires more offspring than other males in the group, suggesting males may