Over the past few days myself and my wife have noticed two green parrots eating from our plum tree. What should we do as although though they seem fine now I’m not sure they will survive the winter?
I can't quite make out from your photo but they look like Ring-necked (aka Rose-ringed) Parakeets. If so they will be perfectly fine. There's thousands and thousands of them living wild in the London suburbs and smaller clusters elsewhere around the country. They are not always welcome because there are concerns about competing with native birds for nesting sites and food and damage to food crops.
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Tony
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They will come to feeders and eat sunflower hearts but at the moment I guess they would prefer your plums.