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The microscopic characteristics of downy barbules of feathers can assist with species identification in forensic investigations, particularly when only minute fragments remain. Using light microscopy (LM) and scanning electron microscopy (SEM), we characterised the feather morphology of 62 species of birds from 18 Orders including representatives of all Orders found in Australia, except Sphenisciformes (penguins). We demonstrate that with a few notable exceptions, Australian birds display similar feather characteristics to their well-studied Northern hemisphere relatives. We also show that the microscopic characteristics of downy barbules can be used to differentiate these Orders. A more detailed investigation of 39 parrot species revealed substantial similarities among the species, indicating that microscopic characteristics could not differentiate among parrot species. However, there were some features (barbule length and macroscopic features, i.e. colour), that may provide clues as to the species of origin. Importantly, the microscopic feather characteristics provide investigators with a simple, fast and cost effective mechanism with which to test assertions about the potential species of origin. This may preclude the requirement for further more expensive testing (such as DNA analysis) or direct further testing towards a smaller, more targeted number of species, reducing the amount and cost of testing required. [ABSTRACT FROM PUBLISHER]

Sex biases in bird populations, particularly an excess of males, can threaten small, isolated populations by reducing reproductive rates. A skew in sex-ratio can be caused by (i) differential mortality at conception or hatching, (ii) differential survival to adulthood, or (iii) stochastic population processes. However, an observed sex-ratio bias can also result from a bias in census methods rather than a realised bias. Distinguishing between the two possibilities is critical to identifying the underlying causes. An excess of males has long been observed in the Kangaroo Island population of the endangered South Australian Glossy Black-Cockatoo (Calyptorhynchus lathami halmaturinus) (Psittaciformes: Cacatuidae), and our census data confirm this. Here, we use DNA-based sexing to test the accuracy of morphologically based nestling sex assignments in C. l. halmaturinus. We find that in all but one case, the DNA-based sexing was concordant with the sex assigned as nestlings, thus confirming the validity of nestling plumage-based sexing in a larger sample from this population. Our analysis of nestling sex data suggests that the adult sex-ratio is a function of a skew at fledging and not caused by higher rates of female mortality post fledging. [ABSTRACT FROM AUTHOR]