Vocal structure, behavior and partitioning of all 23 Pternistis spp. into homologous sound (and monophyletic) groups

The aims of this research were (1) to provide a description of spurfowl Pternistis spp. calls and their social context; (2) to describe the divergence of advertisement calls; and (3) to appropriate 23 spurfowl species to homologous sound groups which have been synthesized with recognized monophyletic groups within Pternistis spurfowls. Sound group partitioning was primarily based on male advertisement calls. A total of 218 recordings (rendering ~300 identifiable calls) were analyzed covering 22 out of 23 spurfowl species in Africa. One species was assessed from written accounts. The repertoire size per spurfowl varies between 7 and 11 calls. Spurfowl calls were arranged into three broad categories including (1) advertisement calls; (2) maintenance calls including distress calls, juvenile whining ("mews"), cheeps and comfort calls; and (3) male-female and female-offspring bonding calls. Spurfowl species were set out in eight sound groups of which five were more or less congruent with the monophyletic groups of Hall (1963), but sound groups produced more partitioning as Hall described only five groups relevant to Pternistis spp. The divergence of advertisement calls apparently minimizes hybridization between sympatric species but the "genetic distance" between spurfowl species is relatively small causing hybridization among spurfowl species. Despite the vocalizations of Hartlaub's Spurfowl (P. hartlaubi) differing significantly from the rest of the spurfowls, sound analyses suggest that it remains within Pternistis.