A state of non-specific tension in living matter? Stress in Australian animals

Abstract

Evidence of stress responses in Australian animals is reviewed through a series of case studies involving desert frogs and lizards, small carnivorous marsupials, desert wallabies, a dwarf kangaroo species, the quokka wallaby and a small nectarivorous bird. An operational definition of stress as “the physiological resultant of demands that exceed an animal’s homeostatic capacities” is used to identify instances of stress responses in the field, and to gauge their intensity. Clear evidence of stress responses is found in small dasyurid marsupial carnivores, and desert agamid lizards, both of which are semelparous. Other instances of seasonal stress responses include the Rottnest Island quokka, the Barrow Island euro kangaroo and a small nectarivorous bird, the Silvereye. The review also highlights the high level of physiological adaptation of some desert wallabies, such as the Spectacled hare wallaby, which is able to maintain physiological homeostasis in the field when challenged by conditions of extreme drought. The importance of thermal and hygric refugia for the long-term survival or rock wallabies, which apparently lack any hormonal control of renal function, is also highlighted.