High above Hong Kong’s bustling streets, a rare call still echoes – the screech of the endangered yellow-crested cockatoo. Fewer than 200 remain in the city, yet they represent an incredible 10 percent of the world’s entire wild population.Leading efforts to protect them is Dr. Astrid Andersson, a postdoctoral researcher at the University of Hong Kong. Her team is installing specially designed artificial nest boxes across the city’s trees, offering the cockatoos safe places to breed. Unlike many birds, these cockatoos don’t build nests, instead relying on tree hollows that are increasingly scarce.Andersson’s mission is to place at least 50 boxes, creating new chances for reproduction while allowing scientists to study the species more closely. Once widespread as pets, with more than 96,000 exported from Indonesia in the 1980s and 90s, the cockatoos are now critically endangered, with no more than 2,000 left worldwide. Hong Kong’s population, small but vital, could play a key role in ensuring their survival.