Moult terminology: envisioning an evolutionary approach

The study of avian moult has been inhibited not only by its complexity but by convoluted and often conflicting terminologies that have combined to cloud the subject. Over time, two nomenclatures have emerged with differing bases of definition. The ‘life-cycle' system is used widely in the European literature (Cramp 1988, Jenni and Winkler 2020) and defines moult terms based on timing relative to current-day life-history events, primarily breeding. Conversely, the Humphrey–Parkes or ‘H–P' system (Humphrey and Parkes 1959, as modified by Howell et al. 2003), is used more widely in the New World and Australia (Higgins and Davies 1996, Johnson and Wolfe 2018, Pyle 2008, 2022a, Howell 2010), and defines terms based…