Morphological and dietary differences between common and uncommon subspecies of Crimson Finch, Neochmia phaeton, and Star Finch, Neochmia ruficauda, in northern Australia

Bill measurements and crop contents were collected from the uncommon subspecies of Crimson and Star Finches, Neochmia phaeton evangelinae and N. ruficauda clarescens, at two sites on Cape York Peninsula. Bill measurements and crop analyses were also taken from the widespread and common N. p. phaeton and N. r. subclarescens in Kununurra, Western Australia. Bill depth and bill width differed significantly between species and among subspecies. The common subspecies possessed wider bills and consumed seeds with a larger mean diameter. The range of seed diameters consumed was also related to bill width, but this relationship was apparent only during the dry season. The seeds found and consumed by adult N. r. clarescens during the dry season were also significantly smaller than those taken by immatures. Management implications are discussed.