I am grateful to Laurence Eu for alerting me to this pair of Changeable Hawk Eagles, Nisaetus cirrhatus, an uncommon resident, nesting at Mount Faber this March. They had been nesting at various parts of Mount Faber since 2001 when we found a nest in a Pulai Tree further down the valley.
This time they chose to build its nest high up on a fork in an Ablizia. Luckily it was close to the road. This gave us a great opportunity to study their breeding behavior close up. It is listed as nationally threatened in the Bird Group’s Checklist borne out by less than 10 active nests per season. You can find out more in Tan Kok Hui’s 2011 study on the status and distribution of the Changeable Hawk-eagles in Singapore here.The status and distribution of Changeable Hawk Eagle .
The large nest (left) is made up of small branches that the Hawk-eagle picked up or broke off from the Albizia tree. The Albizias is favored by the hawk-eagles and fish-eagles for nest sites due to its height. Danger from breaking branches has caused matured Albizia woodlands to be cleared.
1 April. The furry white chick looked to be about 2 weeks old. The parent seldom leave the chick alone at this stage. Joyce Chia’s very timely record shot of the chick and parent.
By the time I went down to document the nesting around mid March, the incubation was unfortunately over. A small furry white “ball” can be seen popping up once in a while from inside the nest. Like all parents, they fussed over the young chick, flying in and out of the nest tendering to the newly hatched chick. It would guard the chick by staying in the nest to defer crows and other predators from an easy meal. It also had to keep the chick dry when it rained and cool when the sun got too hot.
According to the many photographers there, the parents would normally bring back rats, lizards, squirrels, common and green pigeons to feed the chick in the morning. They will fly over the nest and drop the prey into the nest for the chick. Later in the day they will pick up any left over food and eat it outside the nest.
During the first month, the pale morph parent will stand guard near the nest for hours on end while the dark morph parent will be out hunting for food. Unlike some raptors, it is not possible to tell the sexes based on their appearances. The chick’s black wing feathers were well formed by mid April. It can be seen moving around the nest to satisfy its curiosity.
By end April, the chick was around 6 weeks old. It was first seen flapping its wings inside the nest. This will help to strengthen its wing. A big bulge at its breast made us wonder if it was deformed. It later disappeared, which meant that it may have been used to store uneaten food. Even at this stage, the parents were seen bringing back branches to maintain the nest ( per comms. Andy Dinesh).
On 12 May, about 2 months after hatching, Johnson Chua was in place and on time to photograph it taking its first flight out of its nest to a nearby branch without any coaxing from its parents. So we now have an estimated duration of the fledgling of the Changeable Hawk-eagle.
The parents would still be dropping food into the nest for the chick sometimes announcing its return with shrill calls. They would end the day with a family bonding time outside the nest in the late evening before retiring for the night.
The chick would perch further away from the nest and wait for the parents, but would stay within the same tree. Its call was very similar to the adults and would use it whenever the parents were about to return with a kill.
At 9 week old, the chick, bottom left in the photo, would be more adventurous and perch further away from its nest.
By the 9th week, the fully grown chick would be more adventurous and started to venture to the other trees nearby. It even flew to the roadside trees to explore and at times perched very close to where the photographers were.
End May, The 10 weeks old chick appeared anxious to do some hunting on its own. C.T. Lim reported not seeing the chick for most of the day. It had flew down to the valley below to join the parents to learn how to hunt for prey. This young hawk-eagle had been the main attraction to the casual visitors, joggers, nature and bird lovers for the past few months at Mount Faber. For the many photographers, birders and fans who have observed its short life span from birth, it had been a privilege. We were delighted that another of our threatened Hawk-eagle will grace our skies and perhaps raise a new brood of its own in the coming years.
Report and photos by Alan OwYong unless stated. Many thanks to all who so generously shared many of the important observations, dates and behavior with me.
A Naturalist’s Guide to the Birds of Singapore. Yong Ding Li, Lim Kim Chuah and Lee Tiah Khee. 2013.
Field Guide to the Raptors of Asia. Toru Yamzaki et al. ARRCN 2012
The Avifauna of Singapore. Lim Kim Seng. 2009.
A field Guide to the Birds of Thailand and South-East Asia. Craig Robson. 2000.