“Guilty conscience”? Herons in aquafarms are more fearful of people

This study was conducted in the coastal areas of Lingshui and Ledong counties and Dongfang City in Hainan Province and Zhanjiang City in Guangdong Province, China.Hainan (108°37′–111°03′ E, 18°10′–20°10′ N) is located in the southernmost part of China, bordered on the north by the Qiongzhou Strait and Guangdong Province and on the west by the Gulf of Tonkin, opposite Vietnam, with an area of 33,900 km2. Hainan Island has a tropical monsoon marine climate, characterized by indistinct seasons, moderate summer temperatures, mild winters, minimal annual temperature variation, and high annual average temperature. The annual average temperature ranges from 22.5 to 25.6°C, with an average annual rainfall of approximately 1,640 mm (Liang et al. 2006).Zhanjiang (109°40′–110°58′ E, 20°13′–21°57′ N) is located in the southwestern part of Guangdong Province, encompassing the entire Leizhou Peninsula and part of the northern peninsula. Zhanjiang is situated in the low-latitude region and experiences a tropical monsoon climate, which is regulated by the marine climate throughout the year, with mild winters and moderate summers. The annual average temperature ranges from 22.7 to 23.5°C. Average annual rainfall is 1,395.5 to 1,723.1 mm (Tian et al. 2024).Herons (family Ardeidae), belonging to the order Pelecaniformes, are medium to large wading birds. In China, there are nine genera and 26 species of herons (Zheng, 2023). They typically inhabit wetland environments such as rivers, lakes, mudflats, and marshes. The widespread distribution of herons renders them as optimal candidates for experimental research aimed at studying differences in anti-predation behavior across various geographic environments. In this study, little egrets (Egretta garzetta) and Chinese pond herons (Ardeola bacchus), which are common in the southern region of China, were used as experimental subjects.This study investigated the potential variations in tolerance to human disturbance between the little egret (Egretta garzetta) and the Chinese pond heron (Ardeola bacchus) in ‘stealing’ environments (aquafarm environments) and non-aquafarm environments, using FID as an indicator. Herons in aquafarm environments were less tolerant (having longer FIDs) to human disturbance compared to herons in non-aquafarm environments. The main cause of this phenomenon could be the harsh deterrents used by humans to prevent herons from ‘stealing’ fish. These deterrents increase the predation risk for herons when ‘stealing’ in aquafarms, causing them to exhibit less tolerance to human disturbance. our study increases understanding of the behavioral response patterns of herons in human-wildlife conflicts and provide valuable insights for more scientific and rational management and protection of Ardeidae species.