There is an urban legend that Hong Kong’s population is descended from cockatoos released from Flagstaff House (the residence of the Commander of the British Forces, now the Museum of Teaware) as the Japanese army advanced on Hong Kong in 1941, but it is almost certainly untrue as the first reliable sightings were reported two decades later. Andersson thinks that most of them were imported in the 1980s at the height of the wild bird trade. Indonesia exported over 70,000 cockatoos between 1981 and 1994 before it became illegal. Cockatoos make difficult pets; they are noisy, destructive, demanding, and unpredictably aggressive. They also live for 60 years. Consequently, many must have escaped or been abandoned. Pet birds usually do not last long in the wild, but enough cockatoos survived to establish a significant population. 

City parrots

The yellow-crested cockatoo is not the only parrot to have become established in an urban area. It is not even the only parrot to have been introduced to Hong Kong. In Kowloon Park, you can find rose-ringed parakeets and Alexandrine parakeets, two closely related green parrots with red beaks and chin markings that make the males look like they are wearing beards. The former has been present in Hong Kong since at least the 1910s, while the latter was introduced in the 1990s. 

Originally from the Indian subcontinent, sub-Saharan Africa, and Southeast Asia, rose-ringed parakeets and Alexandrines have become established in cities from London to Istanbul to Tokyo. Our previous article, “Hong Kong Unloved Trash Birds” discussed traits that make birds successful urban adapters, among which are long lifespan, high intelligence, and sociability. Parrots have all three. At least 60 of the world’s 380 parrot species have established breeding populations outside of their natural range.

However, it is not a given that any parrot can survive in any city. They have to find the right conditions for their species. In Australian cities, the larger relative of the yellow-crested cockatoo, the sulphur-crested cockatoo (Cacatua galerita), has become ubiquitous. However, Andersson says that despite their very similar appearance, yellow-crested cockatoos are very different in genetics and behaviour. The Australian ones have taught each other to open rubbish bins and turn on drinking fountains, but the yellow-cresteds are much more cautious about coming down to the ground. While they have been known to raid rooftop gardens (they especially love Lunar New Year kumquats), they mainly stay up in the trees, eating fruit, flowers, and pith.

Another requirement is the availability of breeding sites. Almost all parrot species lay their eggs in tree hollows, which only form in large, mature trees. These two factors explain why they have stuck so close to urban parks over the last 60 years, especially those built on former British military sites. It turns out that Hong Kong’s former colonial administrators accidentally created a perfect environment for them. 

Old trees and exotic fruit

If you look at aerial photos of Hong Kong from the 1960s or earlier, you will not see very many trees. Hong Kong was continuously deforested for hundreds of years, and soon after the British took over, they proceeded to implement hillside afforestation projects. Their objectives were not necessarily commercial, but to transform the landscape into something more amenable to European sensibilities and ideas of health. However, Japanese troops clear-cut these plantations for fuel during the occupation. 

Nearly all of Hong Kong’s current forests grew back after World War II. On hillsides occupied by squatter villages (i.e. between North Point and Chai Wan), woodlands did not start to recover until the 1970s and 1980s. Aerial photos show that some of the few places where trees survived the war were Victoria Barracks and Whitfield Barracks, which were used by the Japanese military. Most of the Victoria Barracks site became Hong Kong Park in 1991, while Whitfield Barracks became Kowloon Park in the 1970s. Many trees were destroyed at the Hong Kong Botanical Gardens and the University of Hong Kong campus, but a few made it through. In the 1950s, Victoria Park was built on newly reclaimed land. These places now have some of Hong Kong’s oldest trees.

While cockatoos are sometimes spotted in country parks, the majority of them hang around old urban green spaces on Hong Kong Island. The cockatoos have two main roost sites where they sleep at night in groups of 70-80, one at Hong Kong Park and the other at Victoria Park.  

Urban parks also provide cockatoos with a reliable source of fruit and flowers, thanks in part to colonial era botanical policies. The Hong Kong Botanical Gardens was founded in 1864 to research plants that might become economically useful to the British Empire. Besides seeking out useful local trees like lychees, longans and wampees, successive colonial administrations imported trees from all over the empire, including Malaysia, India, Australia, the Carribean and West Africa. Some were brought in for economic reasons, some for ornamental purposes, and others simply because they grew easily. Today, three quarters of urban trees in Hong Kong are exotic species. 

One exotic tree of particular importance to the cockatoos is the red cotton silk tree (Bombax ceiba). Its red flowers are an ingredient in five flower tea, and its silky fibres were once used to stuff cushions, but to cockatoos, their leaves and flowers are a year-round source of food. They also prefer to sleep and nest in them. When Andersson studied cockatoos in Komodo, she found that they favoured another tree from the bombax family that grew there. She guesses that Hong Kong’s cotton trees must have felt familiar to them.

Cockatoos also like the fruit and flowers of three native common urban trees, paper mulberries (Broussounetia papyrifera), the common red-stem fig (Ficus variegata), and the Chinese sweet gum (Liquidambar formosana). Other food sources include exotic bauhinia flowers, palm fruits, and mangoes. Mango trees at Hong Kong Park are thought to have been planted by Indian troops stationed there before World War II.

Not all is well in paradise

Yet Hong Kong’s cockatoos are not as safe as they appear. While adult cockatoos can defend themselves from predators—Anderson has witnessed them aggressively mobbing black kites—their eggs and chicks are vulnerable to kites, palm civets, and snakes. Nor are they safe from poachers. There have been cases of people climbing trees to steal chicks for the pet trade. It is still legal to sell captive-bred cockatoos, and paperwork for wild-caught birds can be faked.  

Their biggest limiting factor is the shortage of nest sites. Andersson estimates that about 80% of their nests have been destroyed over the last 9 years, either by typhoons or by tree pruning. Since cockatoos enlarge tree hollows with their beaks, government maintenance crews often remove the affected branches for public safety reasons. The Leisure and Cultural Service Department also cover hollows with wire mesh, though this is ineffective since cockatoos can easily chew through it. Andersson thinks that the damage that cockatoos do to trees is fairly insignificant. “They’ve been here since the 1960s. If they were killing the trees, we’d be able to see that by now,” she says.  

The shortage of nest sites puts even more pressure on their population. By the standards of birds, cockatoos breed quite slowly. They take about 5 years to reach reproductive age, then lay a clutch of two to three eggs annually, but typically only one chick survives. Andersson has not seen a single successfully fledged juvenile in the last two years, although she acknowledges that it is very difficult to tell juveniles apart from the adults. She suspects that the increase in the cockatoo population, from 50 in 1970 to about 200 today, was fed by continuous escapes and releases from captivity. 

The situation may improve as Hong Kong’s woodlands mature, but in the meantime, Andersson is piloting a project to install nest boxes around Central and Western District, which she calls a win-win solution. These nest boxes are designed to prevent other animals from accessing them, and are equipped with live camera feeds. She says the LCSD has been very willing to cooperate with her as they understand the conservation value of the cockatoos. 

At one point in her research, Andersson surveyed members of the public about how they felt about the cockatoos, and the response was overwhelmingly positive. Seeing such a charismatic bird in such an urban area made people feel more connected to nature. And this is also an important piece of the puzzle in how cities can co-exist with wildlife. People have to care about it. They need to teach their children about it. “Any wildlife that can survive in such an urbanized environment deserves to be helped and supported,” Andersson says, adding that Hong Kong could very well become an example for the rest of the world to follow. 

Sources:

Special thanks to Dr. Astrid Andersson for her interview. 

Hong Kong Birdwatching Society, “Yellow-crested cockatoo Cacatua sulphurea”, Avifauna of Hong Kong, 2 June 2025. 

Mercedes Hutton, “HKFP Yum Cha: Astrid Andersson on Hong Kong’s critically endangered cockatoo population”, Hong Kong Free Press, 2020 January 2024.

Sifeng Wang, Yin Ho, and LM Chu, Diet and feeding behavior of the critically endangered Yellowcrested Cockatoo (Cacatua sulphurea) in a nonnative urban environment

Ryan F. Mandelbaum, “Parrots are taking over the world”, Scientific American, 1 July 2023.

C.Y. Jim, “Provenance of amenity-tree species in Hong Kong”, Arboricultural Journal, Volume 16, 1992.