Rodrigues Solitaire - Behaviour and Ecology

Behaviour and Ecology

Observations of the Solitaire indicate that breeding pairs were highly territorial. They presumably settled disputes by striking each other with their wings; to aid this purpose, they used the knobs on their wrists. It has been suggested that the knobs may have been formed through continuous injuries, as they resemble diseased bone. Fractures in their wing bones also indicate that they were used in combat. It has also been suggested that these fractures may have been the result of a hereditary bone disease rather than battle-injuries. Some evidence (including their large size and the fact that tropical and frugivorous birds have slower growth rates) indicates that the bird may have had a protracted development period. Several accounts state that they defended themselves with a powerful bite. The species may have lived primarily in the island's woodlands, rather than on the shores.

The most detailed account of their habits is Leguat's. He described mating and nesting as follows:

When these Birds build their Nests, they choose a clean Place, gather together some Palm-Leaves for that purpose, and heap them up a foot and a half high from the Ground, on which they sit. They never lay but one Egg, which is much bigger than that of a Goose. The Male and Female both cover it in their turns, and the young is not hatch'd till at seven Weeks' end: All the while they are sitting upon it, or are bringing up their young one, which is not able to provide itself in several Months, they will not suffer any other Bird of their Species to come within two hundred Yards round of the Place; But what is very singular, is, the Males will never drive away the Females, only when he perceives one he makes a noise with his Wings to call to the Female, and she drives the unwelcome Stranger away, not leaving it till 'tis without her Bounds. The Female do's the same as to the Males, whom she leaves to the Male, and he drives them away. We have observ'd this several Times, and I affirm it to be true.

The Combats between them on this occasion last sometimes pretty long, because the Stranger only turns about, and do's not fly directly from the Nest. However, the others do not forsake it till they have quite driven it out of their Limits. After these Birds have rais'd their young One, and left it to itself, they are always together, which the other Birds are not, and tho' they happen to mingle with other Birds of the same Species, these two Companions never disunite. We have often remark'd, that some Days after the young leaves the Nest, a Company of thirty or forty brings another young one to it, and the now fledg'd Bird, with its Father and Mother joyning with the Band, march to some bye Place. We frequently follow'd them, and found that afterwards the old ones went each their way alone, or in Couples, and left the two young ones together, which we call'd a Marriage.

The clutch was described as consisting of a single egg; given the bird's large size, this led to proposals that the Solitaire was K-selected (producing a low number of altricial offspring, requiring extensive parental care until maturity). The gathering of unrelated juveniles suggests that they formed crèches, that may have followed foraging adults as part of the learning process.

The size difference between sexes has led to the suggestion that the Solitaire was not monogamous as stated by Leguat, and that this deeply-religious man attributed the trait to the bird for moral reasons. It has been proposed that it was instead polygynous, and the wing-rattling behaviour described for males suggests lek-mating (where males gather for competitive mating display). However, size dimorphism occurs in some monogamous birds; most other pigeons are monogamous as well.

Tafforet's account of aggressive behaviour confirms Leguat's description, adding that Solitaires would even attack humans approaching their chicks:

They do not fly at all, having no feathers to their wings, but they flap them, and make a great noise with their wings when angry, and the noise is something like thunder in the distance. They only ly, as I am led to suppose, but once in the year, and only one egg. Not that I have seen their eggs, for I have not been able to discover where they lay. But I have never seen but one little one alone with them, and, if any one tried to approach it, they would bite him very severely. These birds live on seeds and leaves of trees, which they pick up on the ground. They have a gizzard larger than the fist, and what is surprising is that there is found in it a stone of the size of a henn's egg, of oval shape, a little flattened, although this animal cannot swallow anything larger than a small cherry-stone. I have eaten them: they are tolerably well tasted.

Pierre-André d'Héguerty, writing about his time on the island around 1735, stated that a captive Solitaire (which he described as having a melancholic appearance) would always walk in the same line until running out of space, and then return back.

Many other of the endemic species of Rodrigues became extinct after the arrival of man, so the ecosystem of the island is heavily damaged. Before humans arrived, forests covered the island entirely, but very little remains today due to deforestation. The Rodrigues Solitaire lived alongside other recently extinct birds such as the Rodrigues Rail, the Rodrigues Parrot, Newton's Parakeet, the Rodrigues Starling, the Rodrigues Owl, the Rodrigues Night Heron, and the Rodrigues Pigeon. Extinct reptiles include the Domed Rodrigues giant tortoise, the Saddle-backed Rodrigues giant tortoise, and the Rodrigues day gecko.