By Alan OwYong and Tan Gim Cheong.
The Crested Serpent Eagle, Spilornis Cheela, is listed as a rare resident and migrant in the NSS Bird Group’s Checklist 2021. Earlier authors were divided on its status. Robinson (1927) was not sure of its presence, while Burknill & Chasen (1927) noted that they visited on occasions. Gibson-Hill (1950) recorded it as a resident with small numbers. Chasen considered the subspecies here as the malayensis ( Thai-Malay Peninsula and N. Sumatra). Visiting burmanicus subspecies ( Indochina) have been recorded including one at the Chinese Gardens.
Cindy Chen had been photographing this Serpent Eagle at Goldhill for more than three years. An unusual back view of the eagle looking flustered fending off the mob attack of the Collared Kingfishers was one of her more memorable images of this eagle.
In the late 1980s and early 1990s, two individual Crested Serpent Eagles were residing at the Upper Seletar Reservoir Park. Subsequent records from around the island were mostly single birds and were assumed to be wanderers from Johor.
Over the past decade, a Crested Serpent Eagle had been visiting a patch of open forest at the end Goldhill Avenue. It seemed to be taken up residence there during the past few years, mainly due to the availability of reptiles and rodents there.
The tall Albizia trees fringing the open fields at Goldhill Avenue provide vantage perches for hunting for the Crested Serpent Eagles. Photo: Alan OwYong.
The first record of another bird here was on 14 March 2019 when Art Toh photographed both eagles perched on the same tree. They appeared to be of different sex but no bonding or pairing between the two was seen. Will these two be the real deal?
Photo of the two Serpent Eagles perched on the same tree on 14 March 2019 by Art Toh.
It took almost two years before we got the answer. On 7 March 2021, Julian Wong videoed the mating of this pair on an Albizia tree at the fringe of the Goldhill area. He was surprised to learn that this is the first record of these eagles mating here. This was great news as the Crested Serpent Eagle has no proven breeding records in Singapore.
Julian Wong videoed the first mating of a pair of Crested Serpent Eagles on 7 March.
But it was the photo of a juvenile bird taken by Tan YinLing on 25 May 2021 at the same forest that got us excited. This was the second photo of a juvenile Crested Serpent Eagle in Singapore (the other photo was in August 2018 at Bukit Batok). The first record of an immature was from Botanic Gardens on 11 November 1982. On 12 December 2001, a juvenile was recorded at Kent Ridge Park. Dr. Chaiyan Kasorndorkbua of the Kasetsart Laboratory of Raptor Research, Thailand, commented that this is a malayensis subspecies.
Second photo of the juvenile Crested Serpent Eagle taken on 25 May by Tan YinLing.
Trevor Teo made his own luck, roaming the area for several days, and finally got a close up look at the juvenile eating a snake on 3 June 2021. A just reward for his hard work. Unfortunately he did not see how the juvenile got the snake.
Trevor Teo worked very hard to get this photo of the juvenile with a snake. It was tearing and eating the snake when he saw it.
But the big question remains unanswered. Where did this juvenile come from?
So far no one has spotted any nests around the Malcolm Road area. These eagles build large platform nests with sticks and small branches close to the canopy of tall and secluded trees. They lay one egg and incubate it for 37-42 days. It will take a further 59-65 days before it fledges. The interval between mating to appearance of this Goldhill juvenile was 80 days. This time line looks a bit tight.
Curiously, none of the adults had been seen together with the juvenile, either on the same tree or close to each other. There were no reports of the adults chasing the juvenile away. No feeding was observed.
Juveniles are known to wander around. In a tracking study done in Taiwan, a juvenile was recorded some 20 km away from its natal site.
The Bird Group’s Records Committee will be evaluating this in their next review to determined the origin of this juvenile and change its status if needed.
We wish to thank Cindy Chen, Art Toh, Julian Wong, Tan YinLing and Trevor Teo for sharing their sightings and notes with us and for the use of their photographs.
Lim Kim Seng. The Avifauna of Singapore. Nature Society (Singapore) 2009
Gombobaatar Sundev and Toru Yamazaki (compilers). 2018. A field Guide to the the Raptors of Asia. Volume 1.
In letters Dr. Chaiyan Kasorndorkbua. Kasetsart Laboratory of Raptor Research and Conservation Medicine. Thailand.