Photo by Beste Barki.
My sister, who is spending this fall and winter in Istanbul, photographed this bird last Thursday from the window of her condo in the Ulus district of the city. I am identifying it as the ring-necked parakeet (Psittacula krameri).
These birds are native to certain parts of Africa and Pakistan, India and the neighboring areas. However, there are naturalized colonies in several European countries, including England, Greece and Turkey, that are believed to have been established by birds that escaped from captivity. The records from Istanbul go at least as far back as 1996 (example).