Killdeer parental care when either parent deserts

We observed unmanipulated mate and brood desertion by both sexes in Killdeer Charadrius vociferus, which allowed us to examine variation in parental behaviour under three distinct parental care systems: biparental care, maternal care, and paternal care. We observed 26 broods three times daily until fledging or mortality. Within the population, we observed flexible parental care strategies in the two sexes, involving male or female desertion of offspring and mate. Prior to the male deserting, females exhibited greater parental investment in the brood and males reduced care when compared to pairs in which neither parent deserted. We also found that uniparental females exhibited greater parental effort compared to uniparental males. When common and conflicting parental interests arise, the behaviour of one parent may be a facultative response to the behaviour of the other. Our results support the hypothesis that allocation of parental care may depend, in part, on assessment of mate parental behaviour.