When I purchased the set of four stamps from Ivory Coast, I listed this stamp as showing Madagascar Green-Pigeon (Treron australis), because the name given on the stamp is "Treron Vinago Australis".

While checking for changes which have been made as a result of implementing the Clements list, I noticed that this stamp was listed on Kjell Scharning's site as African Green-Pigeon (Treron calva). I also found that it was listed as such in Flight 14/4. I queried the identification of this Pigeon, and Kjell responded as follows :-
"I discovered that the illustrations on all the stamps in the set are taken from Serle, Morel & Hartwig, Birds of West Africa (1977). In this book this pigeon is called Green Fruit-Pigeon Treron australis, distribution Senegal, Gambia and so on. There is no T calva in this book. In HBW I read that T calva has been considered conspecific with T australis, and I assumed Serle et al was of that opinion. Thus the T australis they include in their book is what we now call T calva. As for the looks, the pigeon on the stamp has a red cere colour, as T calva has (in my HBW). T australis has a blue/grey cere colour."

I am happy to accept this, as I can now include this stamp in my collection. I have scanned an image of the Madagascar Green-Pigeon from Sinclair and Langrand's "Birds of the Indian Ocean Islands" (1998).