Howard Banwell sent in a photo sequence of a female Pink-necked Green Pigeon (Treron vernans) swallowing fruits of the MacArthur Palm (Ptychospermum macarthurii) taken at Singapore’s Seletar Air Base on 15th February 2010.
“We watched her and her mate eating numerous fruits one after the other, but no sign of regurgitation of the seed or skin,” wrote Howard.
An earlier post shows the male Pink-necked Green Pigeon swallowing the same fruit. However, the current post shows the complete sequence of swallowing.
Yellow-vented Bulbul (Pycnonotus goiavier), which has a smaller gape than the pigeon, similarly swallows the fruit whole. Details of the fruit in cross-section showing the pulp and seed can be seen HERE.
It is very possible that the seeds may be passed out after going through the digestive system, as it is relatively small compared to the size of the fruit. But we have yet to be fully convinced that the seeds are not subsequently regurgitated.
Unlike Imperial pigeons, the green pigeons can grind up seeds in their muscular gizzards. From dissections of window-killed birds we know that small seeds are totally destroyed, but a large, hard, palm seed would be more difficult, so any observations of intact seeds in droppings or regurgitates would be valuable.