What is that "green wave" over the Tokyo skyline? We need to go back some 60 years, when a pet craze swept Japan. Huge numbers of rose-ringed parakeets were imported into the country to be sold as pets. Some "flew the coop," escaping from their cages or were released intentionally. Their feral numbers have since swelled to around 1,700 nationwide. Observations have revealed the parakeets both learn behaviors from other birds and exchange information such as feeding sites with their own kind.