Tuesday, September 2, 2014

The curious case of the Red-bellied Spinipig

NB: The following should be prefaced - in the manner of any modern climate debate - with “…I’m not a taxonomic scientist, BUT…”

The July release of the “Illustrated Checklist of the Birds of the World. Volume 1: Non-passerines” (del Hoyo & Collar, Lynx Edicions/BirdLife) [1] marks the start of the brave new era in which BirdLife International team up with the Handbook of the Birds of the World (HBW) crew on the impressively ambitious, if slightly mad, project to review and illustrate the entirety of the world’s avifauna in two volumes. Since BirdLife Australia will adopt these changes by default, unfortunately this means Australia’s ‘official’ bird list is, yet again (groan), being decided by A BOOK. And in this case, a book extraordinarily revising all the species of the world on the premise of a single scientific paper, Tobias et al’s 2010 paper, “Quantitative limits for species delimitation” [2] [available open access here]. The Tobias paper outlines a hitherto untested numerical scoring method for defining whether a pair of related taxa are ‘distinct enough’ to qualify as separate species. The method uses sympatric (co-existing, hence undisputed) species pairs to calibrate a universal threshold, which can then be used to test allopatric (geographically separated) pairs, which can be much harder to define. The answer, it turns out, is 7.* 

In a rather left-field move, HBW/BirdlLife have thus resplit the Pilbara’s “Rufous-bellied Spinifex Pigeon” (or spinipig as the locals call them) Geophaps ferruginea, which compared to nominate plumifera (now White-bellied Spinifex Pigeon), is:
  • generally redder [ferruginea = rusty]
  • entirely red-brown below, lacking a white belly
  • richer red-brown above (plumifera more grey-brown)
  • only a grey and black pectoral band, i.e. lacks white band
  • slightly smaller
  • plume slightly shorter [3]
  • iris red to orange-red (cf. yellow to orange-yellow) [4]

"Red-bellied" Spinifex Pigeon Geophaps [plumifera] ferruginea, Wickham WA. Note the red (not grey-brown) back.