Alectroenas Nitidissima’s first appearance in Cage of Eden is in chapter 8: http://www.mangahere.com/manga/cage_of_eden/v02/c008/

The Alectroenas Nitidissima is an extinct species of pigeon formerly endemic to Mauritius. Its alternative vernacular name derives from its coloration: the bird, tri-colored white, dark blue and red, reminded Sonnerat, who brought it to the attention of the scientific world, of the Dutch flag.

No unequivocal written records exist of the Alectroenas Nitidissima until 1755, apart from one brief mention by François Cauche in 1651 of similar Alectroenas encountered on Mauritius and Madagascar in 1640. In 1755, Cossigny gave a somewhat more detailed description of the bird, noting that it was becoming rare since the 1730s. He attributed the decline to deforestation and hunting by escaped slaves; as opposed to the Pink Pigeon, which survives until today, the Alectroenas Nitidissima was not seasonally poisonous or unpalatable. In 1801, though, Jacques Gérard Milbert was still able to procure several for food, but he could only find it in the woods of the river gorges. The last specimen, taken in 1826 in the forests of Savanne district, and the 1832 report by Julien Desjardins suggest that in 1830, birds could still be found in the remaining patches of forest around the Mare aux Vacoas. As a claim that one additional bird was shot around 1850 is erroneous, it can be concluded that the Alectroenas Nitidissima became extinct in the 1830s. Apart from habitat destruction and hunting, introduced predators, mainly Crab-eating Macaques, were probably also responsible.