Abstract
The Grey Falcon (Falco hypoleucos) is a desert-living species restricted to the dry centre of Australia. These falcons have a number of unique life-history adaptations that may be crucial for their survival in this harsh environment, but these may, conversely, confine them to these arid regions. In this study we investigated what Grey Falcon feather structure can reveal about the ecology of the species. Specifically, we tested UV reflectance and structural waterproofing of Grey Falcon feathers, and compared these properties across other Australian Falco species. Grey Falcon feathers did not reflect unique UV peaks, nor show any significant difference in structural waterproofing when compared with closely-related sympatric falcon species. This suggests that Grey Falcon feathers have no specific adaptations to prevent the impact of UV or water on their plumage, so feather structure evidently does not help explain the persistence of this species in arid Australia. We suggest that an exploration of the physiological and behavioural thermoregulatory capabilities of this species should provide further insights in understanding how these birds cope with their extreme environment and are confined there.