Systematics of Parrots

Summary Parrots comprise such an homogenous and natural order of birds that it has proved difficult to find substantial characters with which to subdivide them further. The classification, based largely on external morphology, which Salvadori proposed in 1891 has been the main source for almost all subsequent arrangements, which however, are inconsistent in the number of divisions and in the genera composing the divisions. The present paper is an attempt to reconcile the different arrangements by demonstrating instances of convergence and suggesting several additional features which may have use as systematic indicators. The following anatomical, morphological and ethological characters are considered: tongue, hyoid bone, bill, intestine, gall‐bladder, carotid artery arrangements, neonate chick, furcula, skull rump feathers, exposed epidermis, irides, erectile feathers, sexual dimorphism, colour of immature males, copulatory patterns, epigamic and agonistic display, nesting, foliage‐bathing, rain‐bathing, bathing, sunning and head‐scratching; the evidence of hybridization is also discussed. Convergence is demonstrated in ground feeding forms for skull structure, loss of furcula and an indirect head‐scratching behaviour. The following divisions are proposed: Platycercinae (Platycercini, Cacatuini, Nestorini, Strigopini); Loriinae (Loriini, Psittrichasini, Psittaculini, Micropsittini, Psittaculirostrini); Arinae (Arini); Psittacinae (Psittacini). Although this arrangement is very different in its larger groupings from any previous system, it very closely agrees with that of Salvadori in the number and in the constituent genera of the smaller groups.