The distribution and configuration of black on the underwing of this dark-morph Collared Petrel is far more extensive than indicated in the literature. Indeed, the width of the black band on this individual is greater than indicated for any other 'Cookilaria' petrel, whereas species such as Black-winged Petrel are usually indicated to have a distinctly broader band than Collared. It is interesting to speculate whether there is a consistent difference in the width of the band between pale and dark phase birds.

© A. R. Dean