North Queensland Naturalist 51: 103-109
Clifford B. Frith and Dawn W. Frith
The Australian endemic Chowchilla (Orthonyx spaldingii), a medium-sized terrestrial passerine confined to rainforests of the Wet Tropics Region of far north Queensland, remains biologically little known. An interpretation of the significance of its dorsal plumage, common to both sexes, and the sexually dimorphic ventral plumage is given. The terminally spine-shafted tail feathers of logrunners present an example of convergent evolution with tail morphology and function in non-passerine woodpeckers (family Picidae), and these are illustrated. Knowledge of the unusual nesting biology of Chowchillas is briefly summarised. Recent observations at a nest found a longer incubation period than previously known. Limited observation of social interaction between flock members including a female and her juvenile offspring suggest the possibility of an unusual, indirect, form of cooperative breeding but too little is known to confirm this. It is hoped that this contribution will stimulate further pertinent field study.