Breeding ecology of the Black-thighed Falconets in Perak, Malaysia.

By Khoo Siew Yoong

The recent sightings of the Black-thighed Falconet, Microhierax fringillarius, in Singapore after 30 years, created considerable interest of this long-lost former resident there. This seems to be a good time to share some observations of their breeding behavior in this blog with you.

A successful brood of four juveniles

I have been studying the nesting of this falconet around the limestone hills at my backyard in Ipoh since 2005.  

A female “helper” tearing the innards of a bird to feed the chicks.

I followed a particular super productive pair full time from 2007 till present. They renewed their courtship around November to March every year, successfully brooding 3-6 chicks each year with a bumper brood of 6 chicks in 2018. In a 9 year period, between 2011 and 2019, they successfully raise at least 30 chicks.

Courtship of the studied pair. Note the size difference between the male and female.

One interesting aspect I discovered during the study was the “outsider” breeding rendered by helper adults in incubating the eggs, feeding and looking after the chicks. All of them, the parents, the helpers and the chicks roost in the same nest hole in the cliff side. Some years back, I took my Singapore birding friend Alan OwYong and his wife to check on the nesting. They were amazed to count a total of 10 of them flying back cramming into one nest hole to roost!

The nest hole inside the side of the limestone cliffs is perfect for the whole family.
A 3 month old falconet already acquired adult plumage.

Breeding – Incubation: 3-3.5 weeks. Fledging: 2.5-3 weeks. Post fledgling: 1-7,5 months.

Diet – Bat & House swift (caught on the fly), house gecko, bee, dragonfly, butterfly, moth and small birds. Occasionally small rat. Collected more than 60 pellets during one nesting period for Prof, Puan at University Putra Malaysia for analysis by his undergrad students.

Some of the pellet droppings for analysis
 MaleFemaleJuvenile
SizeSmallerLargerSmall
Belly and ThighLight rufousSlight darker rufousLight rufous
ThroatWhite/Light rufousLight to darker rufousWhite/beige
Ear StripeWhiteWhiteRufous
SuperciliumWhiteWhiteRufous
Table 1. Field features of the males, females and juveniles.
Family photo of parents, young and helper showing the different plumages.

I hope that more falconets will expand beyond Johor down to Singapore and establish a breeding colony there.

References:

In correspondence with advice from David Wells and Alan Kemp.

Research expedition with the British Broadcasting Corporation on the Black – thighed Falconet (Microhierax Fringillarins – smallest eagle in the world). 2013.

“Strange Castaways” in the Wonders of the Monsoon Series. British Broadcasting Corporation. Broadcast in 2014.  

Scientific presentation on the Black- thighed Falconet (smallest eagle in the world) at the Kasetsart University – Raptor rehabilitation Unit, Chatuchak, Bangkok. 2017

Fledging Fledgling in Bird Ecology Study Group (28 Jan. 2013). Raptors: Black-thighed Falconette in Bird Ecology Study Group (5 Sept. 2009). Black-thighed Falconet: Mating and nesting rituals in Suara Enggang (29 June 07). Co- authored with K C Tsang. 

2 thoughts on “Breeding ecology of the Black-thighed Falconets in Perak, Malaysia.

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