The ring-necked parakeets are believed to have be brought over from tropical forests in Africa to France in the 1970s by wealthy collectors, when it became fashionable to own exotic birds. Many of them would go on to escape, breed, and make nests in local trees and parks. Sceaux park at Sceaux Castle, around six miles (10km) south of Paris, is said to be home to 90 nests alone. Over half of the 8,000-10,000 in France are said to be in Ile-de-France, with their number having multiplied by 100 in the last 30 years. The parakeets, which reproduce very easily and quickly, are said to present a threat to the French ecosystem and to native birds and animals, including blue tits, small rodents and bats, because their nests are not habitable for other species. They have even been known to hunt rare animals such as the red squirrel.