Madagascan Blue Pigeon (Alectroenas madagascariensis)
Taxonomy and Evolution
George Robert Gray named a new genus, Alectroenas, for the Mauritius blue pigeon in 1840; alektruon means domestic cock and oinas means dove. Alectroenas nitidissima is the type species of the genus, which includes all blue pigeons.
The Alectroenas blue pigeons are closely interrelated and occur widely throughout islands in the western Indian Ocean. They are allopatric and can therefore be regarded as a superspecies. There are three extant species; the Madagascar blue pigeon, the Comoros blue pigeon, and the Seychelles blue pigeon. The three Mascarene islands were home to a species each, which are all extinct; the Mauritius blue pigeon, the Rodrigues blue pigeon, and the Réunion blue pigeon. Compared to other pigeons, the blue pigeons are medium to large, stocky, have comparatively long wings and tails. They all have distinct mobile hackles on thehead and neck. The tibiotarsus is comparatively long and the tarsometatarsus short.
The blue pigeons perhaps colonised the Mascarenes, the Seychelles or a now submerged hot spot island by "island hopping" and evolved into a distinct genus there before reaching Madagascar. Their closest genetic relative is the cloven-feathered dove (Drepanoptila holosericea), of New Caledonia, which they separated from 8–9 million years ago. Their ancestral group appears to be the fruit doves (Ptilinopus), of Southeast Asia and Oceania.
The extinct Rodrigues grey pigeon (Nesoenas rodericana) was once assigned to the genus Alectroenas, but this was erroneous. In reality, it probably belongs to an undescribed genus, as the sternum's shape is very dissimilar in its details to that of Alectroenas or Columba, and indeed to any other living genus of pigeons and doves. It is most similar to that of the Gallicolumba (ground doves) or to a miniature version of the sternum of a Ducula (imperial pigeons).
It contains the following species:
Madagascan Blue Pigeon (Linnaeus, 1766) (Alectroenas madagascariensis) †Mauritius Blue Pigeon (Scopoli, 1786) (Alectroenas nitidissimus) †Rodrigues Blue Pigeon (Hume, 2011) (Alectroenas payandeei) Seychelles Blue Pigeon (Scopoli, 1786) (Alectroenas pulcherrimus) Comoros Blue Pigeon (Bonaparte, 1854) (Alectroenas sganzini) †Réunion Blue Pigeon (Alectroenas sp.)