Ecophysiological Adaptations of the Eastern Spinebill Acanthorhynchus tenuirostris to a High Altitudinal Winter Environment

Abstract

The Eastern Spinebill Acanthorhynchus tenuirostris is the most common honeyeater in the higher parts of New England National Park in winter, where overnight temperatures may fall to -5°C. It is dependent on nectar, the supply of which is highly erratic, being lowest after very cold nights. The birds may experience energy deficits over several successive days. Eastern Spinebills may show several physiological adaptations to such a potentially inhospitable environment involving variable metabolic rates at a given temperature; large differences between day- and night-time resting metabolic rates; and the possibility of hypothemia.