Aside from the Dodo and the Rodrigues Solitaire, there were at least four and possibly five endemic species of pigeon inhabiting the Mascarenes, of which only one, the Mauritius Pink Pigeon (shown at top of post), barely survives. In addition the Madagascar Turtle Dove was present and either survived or was reintroduced from Madagascar.
The main causes of the extinctions were rats, monkeys, and most seriously hunting. Judging from the behaviour of the surviving Pink Pigeons, the birds had practically no anti-predator responses and would not learn caution, or at least were wiped out too quickly to acquire any.
The pigeons can be divided into two genera, the first, Nesoenas with affinities with Africa included the Madagascar Turtle Dove and the Pink Pigeons (two species on Mauritius and Reunion, of which the Mauritius form survives), the second, Alectroenas (Blue Pigeons), with Asian affinities and species on Mauritius, Rodrigues, and probably Reunion. Why the Blue pigeons died out is not altogether clear – Alectroenas pigeons are still widespread on the Comoros Islands and the Seychelles despite human presence. Possibly habitat destruction overwhelmed them too quickly to adapt. The loss of the Mauritius Blue Pigeon, known as the Pigeon Hollandais because its colours resembled the Dutch flag, is a great loss to the islands – a picture of the Seychelles Blue pigeon is shown here:
As well as losses, several species of pigeon have been introduced to the islands – the ubiquitous feral pigeon of course, as well as Spotted Dove and Laughing Dove (both from Africa) and the Zebra Dove of South East Asia. These do not seem to compete directly with Pink Pigeons but they are potential reservoirs of disease.
Today the Pink Pigeon is the subject of intensive effort to rehabilitate the species. Bristol Zoo has bred them in the past, but it has proven extremely difficult to breed outside of Mauritius, and there are currently 49 in European zoos (including four at Bristol), with another 43 in the USA. In the islands breeding and protection of wild nests has boosted the population, and as of December 2008 the wild population stood at 393 birds. This sounds very small, but is a considerable improvement on the situation in 1986, when only 12 birds could be found at the only site they survived in.
Aside from predators, the main threat appears to be habitat degradation. Pink Pigeons are adapted to feed both on the ground at at the end of long branches, and deforestation and introduced plants do not provide the correct food. Fortunately they take readily to bird tables, so supplemental feeding is easy to provide. Indeed, there was an attempt to release birds in one of the botanic gardens on Mauritus. The birds survived, and even bred, but were wiped out by small boys with catapults, for who they made easy targets.
Despite the setback, new populations are being created. Most recently a new sub-population using translocated birds was established at the lower Black River Gorges, and the first fledgling left the nest in September 2008.
As the Reunion Pink Pigeon was closely related to the Mauritius form, which was its ancestor, it might be possible in the future to reintroduce them to Reunion. Unfortunately, at this point politics intervenes. Whereas Mauritius, with Rodrigues, was a British colony and is now independent, Reunion is a French Overseas Department, so there is less connection between conservation on Mauritius and Reunion than there should be.