Newton's parakeet (Psittacula exsul), also known as the Rodrigues parakeet or Rodrigues ring-necked parakeet, is an extinct species of parrot that was endemic to the Mascarene island of Rodrigues in the western Indian Ocean. Several of its features diverged from related species, indicating long-term isolation on Rodrigues and subsequent adaptation. The rose-ringed parakeet of the same genus is a close relative and probable ancestor. Newton's parakeet may itself have been ancestral to the endemic parakeets of nearby Mauritius and Réunion. Around 40 centimetres (16 in) long, Newton's parakeet was roughly the size of a rose-ringed parakeet. Its plumage was mostly greyish or slate blue in colour, which is unusual in Psittacula, a genus containing mostly green species. The male had stronger colours than the female and possessed a reddish instead of black beak, but details of a mature male's appearance are uncertain; only one male specimen is known, and it is believed to be immature. Mature males might have possessed red patches on the wing like the related Alexandrine parakeet. Both sexes had a black collar running from the chin to the nape, but this was clearer in the male. The legs were grey and the iris yellow. Some 17th-century accounts indicate that some members of the species were green, which would suggest that both blue and green colour morphs occurred, but no definitive explanation exists for these reports. Little is known about its behaviour in life, but it may have fed on the nuts of the bois d'olive tree, along with leaves. It was very tame and was able to mimic speech. Newton's parakeet was first written about by the French Huguenot François Leguat in 1708 and was only mentioned a few times by other writers afterwards. The specific name "exsul" is a reference to Leguat, who was exiled from France. Only two life drawings exist, both of a single specimen held in captivity in the 1770s. The species was scientifically described in 1872, with a female specimen as the holotype. A male, the last specimen recorded, was collected in 1875, and these two specimens are the only ones that exist today. The bird became scarce due to deforestation and perhaps hunting, but it was thought to have been finally wiped out by a series of cyclones and storms that hit Rodrigues in the late 19th century. Speculation about the possible survival of the species, though unfounded, lasted as late as 1967.
Taxonomy Newton's parakeet was first recorded by François Leguat in his 1708 memoir A New Voyage to the East Indies. Leguat was the leader of a group of nine French Huguenot refugees who colonised Rodrigues between 1691 and 1693 after they were marooned there. Subsequent accounts were by Julien Tafforet, who was marooned on the island in 1726, in his Relation de l'Île Rodrigue, and then by the French mathematician Alexandre Pingré, who travelled to Rodrigues to view the 1761 transit of Venus.
In 1871, George Jenner, the British magistrate of Rodrigues, collected a female specimen; it was preserved in alcohol and given to Edward Newton, a British colonial administrator in Mauritius, who sent it to his brother, the ornithologist Alfred Newton. A. Newton scientifically described the species in 1872 and gave it the scientific name Palaeornis exsul. "Exsul" ("exiled") refers to Leguat, in that he was exiled from France when he gave the first description of the bird. Newton had tried to find a more descriptive name, perhaps based on colouration, but found it difficult. He refrained from publishing a figure of the female in his original description, though the journal Ibis had offered him the space. He instead wanted to wait until a male specimen could be procured since he imagined it would be more attractive. The female, which is the holotype specimen of the species, is housed in the Cambridge University Museum as specimen UMZC 18/Psi/67/h/1. A. Newton requested further specimens, especially males, but in 1875 he finally published a plate of the female, lamenting that no male specimens could be found. Tafforet's 1726 account had been rediscovered the previous year, and A. Newton noted that it confirmed his assumption that the male would turn out be much more colourful than the female. Newton's collector, the English naturalist Henry H. Slater, had seen a live Newton's parakeet the year before, but was not carrying a gun at the time. On 14 August 1875, William Vandorous shot a male specimen. It may have been the same specimen Slater had observed. It was subsequently sent to E. Newton by William J. Caldwell. This is the paratype of the species, numbered UMZC 18/Psi/67/h/2 and housed in the Cambridge Museum.
In 1876, the Newton brothers noted that they had expected the male would be adorned with a red patch on the wing, but that the absence of this indicated it was immature. They still found it more beautiful than the female. These two specimens are the only preserved individuals of the species. The mandible and sternum were extracted from the female specimen, and subfossil remains have since been found in the Plaine Corail caverns on Rodrigues. The American ornithologist James L. Peters used the name Psittacula exsul for Newton's parakeet in his 1937 checklist of birds, replacing the genus name Palaeornis with Psittacula, wherein he also classified other extant parakeets of Asia and Africa.
Evolution Based on morphological features, the Alexandrine parakeet (Psittacula eupatria) has been proposed as the founder population for all Psittacula species on Indian Ocean islands, with new populations settling during the species' southwards colonisation from its native South Asia. Features of that species gradually disappear in species further away from its range. Subfossil remains of Newton's parakeet show that it differed from other Mascarene Psittacula species in some osteological features, but also had similarities, such as a reduced sternum, which suggests a close relationship. Skeletal features indicate an especially close relationship with the Alexandrine parakeet and the rose-ringed parakeet (Psittacula krameri), but the many derived features of Newton's parakeet indicates it had long been isolated on Rodrigues.
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