Parrots in Irvine Park

Tramping around Irvine Park in Orange County, California, I saw and heard three green parrot-like objects that were flying from one sycamore tree to another. Eventually, one of them roosted where I could see it. I took this picture with my digital camera on maxiumum digital zoom. I presume they are escapers from captivity or perhaps naturalized. But I don’t know the species.