The Black-thighed Falconet (Microhierax fringillarius), 15-17 cm in size and monotypic, can be found quite easily in Peninsular Malaysia. In early 2007, Ms Connie Khoo, a passionate birder and digiscoper, spent time in the heat of the day keeping watch as well as making detailed notes on the nesting cycle of this bird.
The nest or eyrie was about 10 meters above ground on the cliff face near Kek Lok Tong in Ipoh, Malaysia, an area famous for its limestone hills and caves. The image above gives you an idea of the type of limestone habitat where the nesting took place.
She noticed four adults looking after four chicks. The four chicks most probably came from one pair of adults while the other two adults were probably helpers. It is known that raptors can be sociable in that they come together to help each other during the breeding periods. This has also been observed in Silver-breasted Broadbill (Serilophus lunatus), seen in Bukit Tinggi during the last nesting season, where helpers got involved in nest building.
Copulation took 30 seconds to about 1 minute 12 seconds to complete. Observations in 2005 and 2006 recorded 1 minute 28 seconds, although it cannot be confirmed whether the same birds were involved.
On 5th April the female was possibly incubating her eggs, which can be from two to as many as five. The female stayed in the nest for long periods, occasionally appearing at the nest entrance for fresh air and to ease herself (above left). All this time the male would deliver prey for her to eat. And he would leave in about 10-30 seconds after delivering the food.
The incubation period was about 3-4 weeks and the chicks fledged in another 4-5 weeks. On 2nd May, the first chick was seen covered with white down feathers, and was probably about 7-10 days old. The image at the top (below the limestone cliff) shows a 15-18 days old chick at the entrance of the nest.
On 31st May a young juvenile was seen strengthening its jaw by yawning for about 50 minutes (right). When the male brought food, the juvenile finished it quickly and continued yawning for another 20 minutes. This yawning exercise was seen again on 2nd June and lasted 35 mintues.
The juveniles were fed dragonflies, butterflies (above right), beetles, spiders (above left), small birds like sunbird, tailorbird, munia (below right) and tree sparrow. Occasionally there would be a small lizard or a rat. However when the chicks were very young they were fed only dragonflies, beetles, moths, butterflies and spiders.
Occasionally, mynas and starlings would appear around the eyrie. Invariably the adults would fly back to chase away the intruders. On 7th May at 11.08 am, a tree sparrow appeared and perched just outside the nest. The female falconet suddenly emerged from the nest and caught the surprised sparrow (above left).
By 2nd June the juveniles must have grown quite a bit as one was observed catching a dragonfly by itself (below). However they still needed the parents to catch for them more substantial meals like birds and other small prey. During this period when the juveniles were actively exploring the surrounding areas, the adults were constantly keeping a watchful eye on them, to prevent them from becoming prey to other birds.
On 5th and 9th June when Connie again checked the eyrie, she could not see all the four juveniles. Only one or two adults were in the vicinity. The rest of the adults were possibly teaching the juveniles how to hunt. At 10.25 am she saw one female with one juvenile flying back to sit on the wire. Shortly after, the female left the juvenile and twice brought back a dragonfly each time for the same juvenile. The juvenile was then yawning a lot, possibly to continue strengthen its jaw.
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Connie Khoo
Ipoh, Perak, Malaysia
19th June 2007
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