Assumption Rail (Dryolimnas cuvieri ssp. abbotti)

Assumption Island or Île de l’Assomption is a small coral island that lies south of the Aldabra atoll in the Indian Ocean; the island is home to at least to endemic bird taxa, the Abbott’s Sunbird (Cinnyris sovimanga ssp. abbotti Ridgway) and the Assumption Rail, which is sometimes considered a subspecies of the Malagasy White-throated Rail ((Dryolimnas cuvieri (Pucheran)).

The island had large guano deposits ….

There is a contemporary report of the rail that was made one year before the guano mining started.:

“On first entering the belt of trees and low bushes which fringes the shore, we were greeted by a chorus of squeals and grunts, as though a litter of pigs was hidden in the cover. This remarkable noise proceeded from a number of rails, birds much like our water-rail but rather more stoutly built, and with wine-red breasts, barred on the flanks and belly with black and white. These rails were very tame, and walked about close to us in a perfectly unconcerned manner. We never saw one of them fly, or even try to do so: they trusted entirely to their legs when pursued. In several patches of bush we came across family parties of them, and although the young were mostly full-grown and feathered, we saw several which were still covered with black down. they were found on all parts of the island, except on the summit of the sandy hill on the windward side. While uttering its remarkable note, his rail stands quite still and puffs out all its feathers; from what I observed I should say that the skin of the throat is also expanded. The notes are loud – a strange mixture of squealing, grunting and booming – and during its song the bird appears to be gradually collapsing, until at the end it is once more of normal size. I have heard our English water-rail utter a somewhat similar noise when near its nest, but its cries are never so loud as those of the Assumption rail. We caught two of them alive and brought them safely to England, and they are at the time I write living in the London Zoological Gardens.” [1]

During the early 20th century it was largely destroyed due to the guano mining and the native fauna and flora were severely affected, Abbott’s Sunbird is still surviving until today, but the endemic rail did not have as much luck. 
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The photo shows the Aldabra Rail (Dryolimnas aldabranus (Günther)), the last surviving flightless rail taxon in the whole Indian Ocean region; this form is still officially treated as a subspecies of the White-throated Rail but should actually considered as a full species.

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syn. Dryolimnas cuvieri ssp. abbotti (Ridgway)

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References:

[1] M. J. Nicoll: Three voyages of a naturalist: being an account of many little-known islands in three oceans visited by the “Valhalla” R.Y.S.. London: Witherby & Co. 1908
[2] Janske van de Crommenacker; Nancy Bunbury; Hazel A. Jackson; Lisa J. Nupen; Ross Wanless; Frauke Fleischer-Dogley; Jim J. Groombridge; Ben H. Warren: Rapid loss of flight in the Aldabra white-throated rail. PLoS ONE 15(11): 1-19. 2019

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edited: 03.01.2023