| Stress response is an important mechanism for animals to cope with environmental or social stress. It is characterized by activation of the hypothalamic-pituitary-adrenal axis (HPA axis) and production of glucocorticoids, which is corticosterone in most bird species. The corticosterone level of a bird can be utilized to determine whether it is under stress, to identify the factors that may induce or influence such stress response, and ultimately, to reveal the mechanism of how the birds adapting to the environmental changes and balancing the energy distribution in different stages of life history. Furthermore, the long-term monitoring of corticosterone level can also provide the survival and health status of individuals, which important implications for conservation of endangered birds. This paper reviewed the factors that induce stress response in birds, including weather, predation pressure, food availability, human interference, urbanization and social stress; summarized the factors that may affect the degree of stress response of birds, including photoperiod, habitat, gender, age, social class and early experience. Moreover, this review also outlined the research contents with high potential for further research, including feather corticosterone determination, chronic stress as well as the application of stress response in the fields of animal personality, cognition and system development. |
