Abstract:[Objectives] The Himantopus himantopus is a widespread species whose breeding sites are mainly distributed in northwest, northeast, north, and east China. Although a lot of researches have observed and recorded the reproductive behavior of H. himantopus, most of them focused on a certain feature of reproductive behavior, and few studies completely observed and recorded the whole breeding cycle and behavior. [Methods] The study was conducted in Qinzhou Bay Balushui Wetland, Fangchenggang City, Guangxi Zhuang Autonomous Region (March to September 2021). The breeding situation in 2021 is shown in Table 1. We observed the breeding behavior of H. himantopus by scanning in 2019 and 2020 to confirm the general breeding sites and seasons. After determining the nest site, the information of state, type, material, and morphological parameters (length, width, and depth) and clutch number of each nest, and size of each egg in every nest were recorded and measured. We selected 6 nests of H. himantopus at random by target animal sampling method to record the behavior of nesting, laying, and incubating the egg. A nest of couple of H. himantopus and the all-event sampling method were used to observe the behavior of mating, brooding, and defense. The time spent at the nest by both sexes was analyzed using t-test, and analyses were completed by SPSS 25.0. During the observation period, male and female adults of both sexes were distinguished by their breeding plumage:males had brightly colored breeding plumage with black eyes, head, nape of neck, back, and wings. Females had no black-colored breeding plumage on the head and neck, but had gray spots behind the eyes (Fig. 1). The observation time was from 7:00 to 19:00, and the reproductive behavior was recorded by infrared cameras at night. We used telescope to monitor each nest from a distance of 10﹣20 m away from the nests. A set of video equipment was also arranged to monitor each nest found at a distance about 1 m away from the nest from 19:00 pm to 7:00 am. The equipment consists of an infrared camera (AM-860 dv-58g., Wuhan, China) and a battery with a capacity of 2 000 mAh. [Results] We observed the reproductive behavior of 39 nests of H. himantopus and found:1) They inhabited salt fields, shrimp ponds, and fishponds while most nests were placed in salt fields. 2) There are four nest types, including nests made of rick, nests made of gravel, nests made of dirt, and nests built on Eleocharis acicularis. These nesting materials consist of rick including Gramineae or Cyperaceae, and some mixture like gravel, shell, and so on. Nest outer diameter was 23.3 ± 10.7 cm, nest inner diameter was 11.2 ± 1.9 cm, nest depth was 1.6 ± 0.5 cm, nest height was 6.5 ± 4.3 cm (n = 39). The nest building period lasted 3 ± 2 d (n = 6) according to the complexity of the nest (Table 1, Fig. 2). 3) The clutch sizes are 2﹣4, and 1 egg was laid with a 1﹣2 d interval and finished within 7 d. 4) The incubation time of females was longer than that of males (female:8 550 ± 245.9 min, male:7 530 ± 263.3 min, P > 0.05), but the difference was not significant, and the incubation period was 25 ± 2 d (n = 6, Fig. 3). 5) In the first and middle stages of brooding (the chicks are 1 to 20 d of age), the female brooding time was nearly twice than that of the male. In the later stages (the chicks over 20 d of age), the time of brooding between the male and the female gradually decreased, and the time of brooding without the parents became longer. The nestling period lasted 26 ± 3 d (n = 6, Fig. 4). 6) For different threat sources, the defense behavior of H. himantopus mainly includes parental defense and group defense (Table 2). [Conclusion] This study is helpful to fully understand the breeding behavior of H. himantopus in the study area and provide a basis for the conservation of H. himantopus.