Effects of male attractiveness on preferential mating, reproductive performance and offspring sex ratio in Chukar breeder partridges (Alectoris chukar).

1. Female Chukar partridges (Alectoris chukar) strategically adjust maternal reproductive strategies based on male attractiveness, which can influence both reproductive success and offspring sex ratio.2. In this study, female-choice trials identified preferred and non-preferred males. Using a crossover design, each female was sequentially paired with the preferred and non-preferred males, separated by a two-week physiological reset interval.3. Reproductive parameters, including daily egg production, fertility, hatchability (of both set and fertile eggs), embryonic mortality and the primary and secondary offspring sex ratios, were determined via molecular sexing and abdominal cavity examination.4. Notably, offspring sex ratio did not deviate from 50:50 in preferred-male pairings, whereas females that mated with non-preferred males produced a female-biased sex ratio in both the primary and secondary stages.5. In terms of reproductive performance, females paired with preferred males showed significantly higher fertility (~8%) and hatchability (15.27% and 10.63% for set and fertile eggs, respectively), while egg production and embryonic mortality remained unaffected.6. These findings highlighted the importance of allowing female mate choice to improve productivity in commercial systems, especially where male scarcity is a concern.