Species and sex divergence in vocalizations between hybridizing role-reversed shorebirds, Northern Jacana (Jacana spinosa) and Wattled Jacana (Jacana jacana)

Species-specific vocalizations can act as a reproductive isolating mechanism between closely related populations. We analyzed vocal divergence between two hybridizing species of sex-role reversed polyandrous shorebirds, the Northern Jacana (Jacana spinosa) and Wattled Jacana (Jacana jacana). We found that J. spinosa calls have higher peak frequency and fundamental frequency than J. jacana calls. We also compared calls between males and females, as both jacana species are sex-role reversed and females compete for male mates. Males produce calls with a higher peak frequency, exhibit shorter note lengths and emit a greater number of notes within a calling bout than females, which could relate to mate attraction. These results suggest that vocal divergence could act as a behavioral barrier to limit hybridization between the species and vocalizations may function differently between male and female jacanas.