The Black-Thighed Falconet in Singapore.

THE BLACK-THIGHED FALCONET IN SINGAPORE

Lim Kim Seng

Introduction

The Black-thighed Falconet Microhierax fringillarius was previously classified as a resident breeder as there had been specimens collected from Singapore as well as records since the 1920s and up to the 1990s (Lim 2009) but is likely to have become extirpated thereafter. It was re-categorized by the Nature Society (Singapore) Bird Group Records Committee, or NSSBGRC, as a non-breeding visitor as there have been no confirmed breeding record and no confirmed sightings for thirty years (Lim 2021). The Black-thighed Falconet was put into Category B, a category for wild birds, resident, visitor or vagrant, that have not been recorded for thirty years. In 2021 alone, however, there were three separate records of Black-thighed Falconet and as a result, it was re-instated in Category A by NSSBGRC.

Black-thighed Falconet was re-instated by the NSSBGRC in 2021. Photo taken at Panti Forest by Jimmy Chew.

Global Range, Habitat Requirements, Altitudinal Range, Breeding Habits and Conservation Status of Black-thighed Falconet

The Black-thighed Falconet is a monotypic species first described by Drapiez in 1824. It is one of five falconets in the world, all of which occur in southern China, South and Southeast Asia. Its natural range spans the Thai-Malay Peninsula, Sumatra, Borneo and Java. Its habitat is primary and secondary forests (including on limestone), edges of forests, rubber plantations, fruit orchards, cultivated land, parkland and wooded gardens up to 1,700 m (Ferguson-Lees & Christie 2000, Lim et al 2020, Wells 1999). The Black-thighed Falconet occurs as a common resident in most parts of its range and it is not known to undertake any movements (Robson 2000). In north Borneo, this species is replaced by the endemic White-fronted Falconet M. latifrons (Myers 2009).

In the Thai-Malay Peninsula, it breeds from November to July (Khoo 2021, Wells 1999). Nests are usually in tree cavities abandoned by woodpeckers and larger barbets, mostly in dead trees. In a site monitored in Perak, Malaysia, birds used a cavity in a limestone outcrop and nested successfully (Khoo 2021). Clutch size is three to six. The young remain with their parents for at least two months after fledging (Khoo 2021, Wells 1999).  It breeds from December to June in Borneo (Myers 2009). There is also evidence of communal feeding by birds other than parents, possibly by older siblings, and birds have also been seen to use old nest cavities as communal roost sites (Khoo 2021).

In Perak, Malaysia, they used cavities in Limestone outcrops to nest. Photo: Khoo Siew Yoong.

The Black-thighed Falconet is treated as “least concern” by IUCN (BirdLife International 2016).

Identification and Ecology of Black-thighed Falconet

The Black-thighed Falconet is one of the smallest raptors in the world at 15-17 cm in length from bill tip to tail tip. It is the same size as the White-fronted Falconet but smaller than Collared and Pied Falconets and has the distinction of being the smallest bird of prey of the world! In comparison, the Coppersmith Barbet Megalaima haemacephala measures 15-17 cm, Sunda Pygmy Woodpecker Yungipicus moluccensis, 13 cm and Yellow-vented Bulbul Pycnonotus goiavier measures 19-21 cm. Females are slightly larger than males and an adult weighs about 43 g (Wells 1999). In terms of its jizz, the Black-thighed Falconet has a big-headed, stout-bodied appearance with a medium-sized tail.

The small size of the falconet makes it hard to confuse with other birds although distance may make identification challenging as this species usually hawks from tall trees. It is mostly black on the head, eyestripe, ear patch, upperparts, bill, leg and tail, with mostly white on forehead, eyebrow and underparts, and orange-rufous on throat and lower breast to vent. Juveniles show pinkish horn bill and cere, rusty eyebrow and ear stripe, pale fine edges to upperparts and less rufous on lower underparts.

Its flight is rapid and direct, with fast wingbeats and sharp pointed wings, often accompanied by short periods of gliding.

Its voice is a shrill squeal kweer-week (Wells 1999).

Black-thighed Falconets hunt socially or alone, making sorties from a dead tree. Its diet is mainly arthropods, typically termites, butterflies and moths, dragonflies, carpenter bees, beetles, mantids, grasshoppers and cicadas, birds such as House Swift Apus nipalensis, sunbirds and munias, mammals such as bats and rats, and geckos (Khoo 2021, Wells 1999). Prey is usually snatched on the wing, occasionally from the ground, to be consumed from a perch, and there is evidence that falconets choose flowering trees with an abundance of nectar feeders to hunt (Wells 1999).

Birds indulge in head bobbing and tail wagging in close proximity and allo-preening has been observed (Wells 1999).

Historical Status of the Black-thighed Falconet in Singapore

The earliest reference to the occurrence of the Black-thighed Falconet in Singapore can be found in Bucknill & Chasen (1927) who stated that it “sometimes visit Singapore”. Gibson-Hill (1950) mentioned that it was “resident in small numbers” while RAFOS (1966-1969) and Tweedy (1970) mentioned the existence of several records in the 1960s.

There were no records until almost two decades when I found the first of four sight records within a period of seven years, all from a dead durian tree in my wooded garden in Jalan Ulu Sembawang in the north of Singapore. All records were of singles and included a juvenile seen on the following dates – 11 October 1979, 2 October 1983, 1 December 1983 and 12 April 1986 (Lim 1992). These records indicate the presence of a small and possibly breeding resident population in the area or that of non-breeding visitors from nearby Johor state, Malaysia. There were no further records from this site which was resettled and developed as part of the new Sembawang Estate in the early 1990s. Our most recent record was an adult seen on a dead tree, near the current Ranger’s Station, in the Central Catchment Nature Reserve on 7 October 1990 (Lim 2009).

In addition to these records, there were also four unconfirmed records between 1992 and 2005 from Sime Road, Loyang and Bukit Batok Nature Park. There are also nine specimens collected from MacRitchie Reservoir, Jurong and Singapore in the Lee Kong Chian Nature History Museum collection.  

Due to the fact that there have been no records for thirty years and also no confirmation of breeding, the Black-thighed Falconet’s status was reviewed by NSSBGRC in early 2020 as no longer fitting that of a wild bird for Category A, which is the category for all wild birds recorded within the last thirty years. It was re-categorised as belong to Category B, which is the category for all wild birds recorded within Singapore but not within the last thirty years (Lim 2021).

As fate would have it, soon after the release of the new checklist, news came of our first sighting of Black-thighed Falconet since 1990. This came from a juvenile that was seen and photographed by Lee Lay Na at a HDB block in Yishun Street 71 on 12 February 2021 (Tan, G.C. & Lim, G. 2021). The report of a juvenile is interesting as it indicates local or regional breeding.

A typical perch of the Black-thighed Faconet on top of tree at Goldhill Avenue by Art Toh.

There were two additional records, both also backed by photographs. One was a bird photographed using the top of a tree at Goldhill Avenue on 20 May 2021 by Art Toh (Tan, G.C. 2021) while the second was another adult from Jalan Mashhor on 9 July 2021, reported by Art Toh and Tan Choon Siang, and still present on 12 July 2021, reported by Vincent Lao (Lim, G. et al 2021).

A far away photo of the second adult falconet taken at Jalan Mansor two months later again by Art Toh.

These three sightings from 2021 have the effect of reinstating the Black-thighed Falconet into the Singapore List once again. At the moment, it is probably best considered a rare non-breeding visitor due to the short-term nature of their occurrences in 2021. Hopefully, one day, we will find them nesting in Singapore again.

Concluding Remarks

Birders and bird photographers are much more active than two decades ago. There are people at various locations in Singapore every day and most of them carry some sort of photographic equipment with them. This number of people watching birds daily is bound to yield rewards in the form of documenting the occurrence of rarities as well as species that are either new to Singapore or those thought to have been extirpated. Recent records of Javan Plover and Green Broadbill attest to this increased opportunity of detecting something really sensational!

Would-be falconet seekers are encouraged to focus on sites in the central and north of Singapore, where all confirmed sightings have been made since 1979. Bukit Brown would be another place to pay attention to given the recent record (and nearby, in Goldhill). Searches on Pulau Ubin may also yield results due to the island’s proximity to Malaysia as well as the island’s reputation for attracting Malaysian visitors. Prime habitats to look for this elusive raptor are the edges of forests and woodland as well as areas where there are tall trees or snags.

It is hoped that birders and bird photographers will continue to help us make new discoveries or re-discoveries in the case of the Black-thighed Falconet, the smallest bird of prey in the world.

Acknowledgements

I would like to thank Yong Ding Li for helpful suggestions with the drafting of this article, Jimmy Chew, Khoo Siew Yoong and Art Toh for the use of their photographs.

References

BirdLife International. (2016). Microhierax fringillarius. The IUCN Red List of Threatened Species 2016. Downloaded on 10 September 2021.

Bucknill, J.A.S & Chasen, F.N. (1927).  The birds of Singapore Island. Government Printing Office, Singapore.

Ferguson-Lees & Christie, D.A. (2001). Raptors of the World. Christopher Helm, London.

Gibson-Hill, C.A. (1950). A checklist of the birds of Singapore Island. Bull. Raffles Mus. No. 21: 132-183.

Khoo, S.Y. (2021). Breeding ecology of Black-thighed Falconets in Perak, Malaysia. Nature Society (Singapore) Bird Group. https://singaporebirdgroup.wordpress.com/tag/black-thighed-falconet/

Lim, G., Lee, I. & Tan, G.C. (2021). Singapore Bird Report – July 2021. Nature Society (Singapore) Bird Group.  https://singaporebirdgroup.wordpress.com/category/monthly-bird-reports/

Lim, K.S. (1992). Vanishing birds of Singapore. Nature Society (Singapore), Singapore.

Lim, K.S. (2009). The avifauna of Singapore. Nature Society (Singapore), Singapore.

Lim, K.S. (2021). Bird Records Committee Report (January 2021). Nature Society (Singapore) Bird Group. https://singaporebirdgroup.wordpress.com/2021/02/02/birds-records-committee-report-jan-2021/

Lim, K.S., Yong, D.L. & Lim, K.C. (2020). A field guide to the birds of Malaysia and Singapore. John Beaufoy Publishing, Oxford.

Myers, S. (2009). A field guide to the birds of Borneo. Talisman Publishing, Singapore.

Royal Air Force Ornithological Society (1966-1969). Bulletins of the Singapore Branch & unpublished correspondence with members.

Tan, G.C. (2021). Singapore Raptor Report, Late Spring Migration, April-June 2021. Nature Society (Singapore) Bird Group. https://singaporebirdgroup.wordpress.com/category/raptor-report/singapore-raptor-report/

Tan, G.C. & Lim, G. (2021). Singapore Bird Report – February 2021. Nature Society (Singapore) Bird Group. https://singaporebirdgroup.wordpress.com/category/monthly-bird-reports/

Tweedy, L. (1970). The birds of Singapore. Army Birdwatching Club (Far East).

Wells, D.R. (1999). The birds of the Thai-Malay Peninsula, Volume One: Non-passerines. Academic Press, London.

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