A non-invasive sexing method reveals the patterns of sex-specific incubation behavior in Saunders’s Gulls (Saundersilarus saundersi)

• Published in: The Korean Journal of Ornithology Vol. 25; no. 2; pp. 69 - 76
• Main Authors: Joo, Eun-Jin, Ha, Mi-Ra, Jeong, Gilsang, Yoon, Jongmin
• Format: Journal Article
• Language: English
• Published: 한국조류학회 31.12.2018; 한국조류학회II
• Subjects: 생물학; Parental Care; 선택교배; Saunders’s gull; 검은머리갈매기; Incubation; Sexing; Sexual size Dimorphism; 성적크기이형; 양육; Assortative Mating; 포란; 성감별
• ISSN: 1225-9179; 2586-6893
• DOI: 10.30980/KJO.2018.12.25.2.69

Sexual dimorphism in birds refers to male-female differences in body size, plumage, color and/or behavior. In general, many seabirds, including the family of Laridae, are monomorphic in plumage-color, which makes the determination of sex difficult in the field because both parents also tend to share a great portion of parental care. The development of an inexpensive sexing tool facilitates understanding the degree of sex-specific parental care in the evolution of the life history. Here, we developed a non-invasive method for the determination of sex using the bill-head morphometric of known captive pairs and applied this tool to wild pairs to document factors underlying male-female parental care during the incubation period of Saunders’s gulls (Saundersilarus saundersi). Males exhibited relatively larger bill-head ratios than their mates within naturally formed pairs in captivity, resulting in the determination of sex in12 wild pairs at the nest during the incubation period. Males and females equally shared the incubation role during the daytime, attending the nest at a high rate of 95%. However, the male’s proportion of nest attentiveness greatly increased with time towards sunset, presumably reflecting the male duty for nighttime incubation. The present study provides a non-invasive method for the determination of sex in a monomorphic seagull species and highlights how male-female incubation behavior is associated with time of the day, rather than other ecological conditions. KCI Citation Count: 0