关键词: 朱鹮, 野化放归, 食性转换, 血液浓缩, 适应性, 种源选择

Abstract:

Objective: This study aims to investigate the foraging selection and adaptability of Nipponia nippon that has long inhabited inland environments to coastal food resources, and to provide a scientific basis for the feasibility assessment, provenance selection, and wild training of N. nippon in re-introduction to the eastern coastal areas. Method: In this study, 51 captive N. nippon trained in the wild in Beidaihe National Wetland Park were used as objects, and six common coastal mudflat species of clam worm, mantis shrimp, siphon-worm, razor clam, short necked clam, and sea crab were selected for feeding experiments in a simulated tidal pool, together with their traditional freshwater food loach. The all-occurrence sampling method was used to record the foraging behavior of the individuals. Before and after feeding on coastal food, fecal samples and blood samples were collected to detect changes in hormone levels and serum biochemical indicators. Independent samples t-test was used to analyze the foraging preference of individuals of different ages for coastal food, and paired samples t-test was used to analyze changes in physiological indicators before and after feeding on coastal food. Result: N. nippon was able to feed on 4 out of the 6 coastal mudflat food species, namely clam worm, mantis shrimp, siphon-worm, and razor clam, which accounted for 44.1% of their daily food intake. There were age-related differences in the preference for coastal food. The food intake of subadults was significantly higher than that of juveniles (P<0.01) and adults (P<0.01), indicating that the subadult stage is a key period for dietary transition. With the extension of the experimental period, the food intake of some coastal food species by N. nippon and the adaptability to these foods increased 53.4% accordingly, suggesting that long-term acclimatization is beneficial to the dietary transition of N. nippon. After feeding on coastal food, the concentrations of corticosterone (P<0.01) and secretory immunoglobulin A (P<0.01) in fecal samples increased significantly, and the content of albumin (P<0.05) in serum also increased significantly. Conclusion: N. nippon can partially feed on specific species of coastal food, and subadults in particular show significantly stronger foraging selection for coastal food, making them suitable as the main group for re-introduction in coastal areas. After feeding on coastal food, N. nippon exhibits a certain degree of hemoconcentration, indicating that traditional freshwater food is indispensable.

Key words: Nipponia nippon, re-introduction, dietary transition, hemoconcentration, adaptability, source population selection