I've written before about Budgies or Parakeets and I've also mentioned Jack Perks, more than once. He's a wildlife photog in the UK, specializing in river fish and has recently published a new book.
I don't think most of us think about the UK having parakeets flying about, but recently Mr. Perks was in London's Hyde Park where there is a healthy population of these colourful birds. They likely originated from pets that escaped as long as 60 years ago and they have done well for themselves, competing successfully for food and nesting sites with the native birds.
Here's a short video: