‘Serpent-eagle special’: Simeulue, Mentawai and Belitung

16th June – 2nd July 2019

Leader: Sumaraja

Participants: Jean-Marc and Francoise Thiollay

‘Mentawai Serpent-eagle’, Sipora © Sumaraja / Birdtour Asia

This custom tour was a little different to our usual endemic-packed tours through the Indonesian archipelago. This time, we used our experience and contacts to put together a slow-paced tour through some seldom-visited islands, specifically targeting the smaller island Crested Serpent-eagle taxa, that could be split in the future. Visiting Belitung, Sipora and Simeulue we found the three taxa we searched for, along several other raptors. Other species, including the endemics, were not targeted, so just came along as welcome bonuses. A final visit further east, in Java, revealed the Endangered Javan Hawk Eagle too.

After the long-haul flight across to Jakarta, we flew up to Belitung. Situated in the Karimata Strait between Sumatra and Borneo, Bangka and Belitung are surprisingly large islands that share a number of Greater Sundas endemics, though the number of Bornean taxa here found on the islands reveal their closer association to the world’s third largest island. Between the two islands there are several distinctions too, one of which is the natunensis race of Crested Serpent Eagle, found only on Belitung and Natuna.

Natuna is one of the more difficult islands in the Greater Sundas to reach, so it’s fortunate several daily flights to Belitung make it an attractive alternative. Belitung is little-known yet contains a lot of interesting species, though rampant clear-fell logging, conversion to Oil Palm and mining is changing the landscape here dramatically. We had an afternoon to orientate ourselves, followed by two full days with the sole aim of finding the serpent eagle. During our scouting mission on after arrival, it was clear how much recent deforestation there had been on the island. Nevertheless, we picked up Changeable Hawk Eagle, Osprey, White-bellied Sea Eagle and Black-winged Kite – a good omen!

On our first full day, broken bridges, deep muddy pools across the length of roads made for difficult access to the better habitat. These frustrations can lead to gold however, as while we were busy building a new bridge, we heard the unmistakable call of a Spilornis, and sure enough it soon appeared – ‘Natuna Serpent-eagle’, perching at first 30 metres away before landing above us! Great views enabled us to see the distinctive field marks – soft buff-brown underparts and contrasting grey cheek, dark upperparts and noticeably smaller sized than the Crested Serpent-eagle taxa we were more familiar with. We had repeat views the next day of the serpent eagle, though generally birding was slow, as we stuck to the roads, scanning the skies for further sightings. Thick-billed and Pink-necked Green Pigeons, Changeable Hawk Eagle, Red-crowned Barbet, Blue-breasted Quail, and cracking views of a Hooded Pitta.

‘Simeulue Serpent-eagle’ and ‘Natuna Serpent-eagle’

Our next serpent-eagle taxa to search for was sipora, endemic to the Mentawai island group situated off the west coast of central Sumatra. We opted to visit Sipora, the second largest island in the Mentawai group. We had a couple of days searching for the ‘Mentawai Serpent Eagle’, sipora, perhaps the most distinct of the serpent eagle group given its smaller size, darker plumage and extensive white crown flecking. It’s also one of the hardest of the taxa, as it doesn’t seem keen on soaring, so we knew we might end up needing all of our time here in search of it. We needn’t have worried as on our first morning, after a lot of careful scanning, we picked out a single silent bird sat out exposed, allowing us prolonged scope views of this distinctive bird.

The rest of our stay was predominantly a wet one, certainly not conducive for soaring raptors! We came across many of the Mentawai’s endemic taxa during our eagle scanning, which included the endemic Mentawai Malkoha – split from Chestnut-breasted by both the field guide and Birdlife, ‘Mentawai’ Spangled Drongo – one of the many drongo splits from the field guide, this taxon being somehow lumped with the montane dwelling Sumatran Spangled Drongo. The Barusan islands endemic Barusan Cuckoo-dove, White-bellied Sea Eaglem Roving Cuckooshrike, Blue-rumped Parrot, Olive-winged Bulbul, Asian Glossy Starling, Fiery Minivet, Oriental Pied Hornbill, Ashy Drongo, Slender-billed Crow, Black-headed Bulbul, Crimson Sunbird, Orange-bellied Flowerpecker, White-headed Munia and Ashy Tailorbird.

Though Mentawai islands are renowned for their endemism, particularly primates, due to ridiculously high hunting levels, couple with extensive logging we only managed a brief view of a single Pagai Macaque, along with Mentawai Ground Squirrel.

Returning back to the Sumatran mainland, our next island was Simeulue, reached via Padang and Medan. Simeulue has become increasingly popular since the rediscovery of the Critically Endangered Silvery Woodpigeon here in 2010, having been undetected since 1902. Coupled with some field guide splits and an endemic Otus, it makes for a pleasant couple of days. We had great flight views of Silvery Woodpigeon, though obviously this was

second in our interests. The serpent-eagle found here, abbotti, ‘Simeulue Serpent-eagle’ is one of the easier taxa to find, regularly perched by the roadside. We saw eight of them during our stay here, including one fabulous individual doing just as we had hoped – perched by the roadside! It’s rich brown underparts delicately marked with blackish bars, along with a narrower subterminal band and wing band.

We also found the endemic Simeulue Parrot, distinct from Blue-rumped, the small endemic race of Changeable Hawk Eagle, Fiery Minivet and another distinct Ashy Drongo (this time resembling birds from the monsoon belt of mainland Asia). While at night, it was just the leader who opted for some night-birding to enjoy the endemic race of Great Eared Nightjar and cracking views of the little Simeulue Scops Owl.

Hooded Pitta, Belitung and Barusan Cuckoo-dove

For our final leg, we flew back down Sumatra and across Java to Surabaya. From here, we had a last minute change of heart and decided to visit Mount Bromo, rather than Bawean, for its endemic serpent-eagle as originally intended. Bromo offers a stunning vista, and view over the forest, and offers one of the best viewing sites to observe the Endangered Javan Hawk Eagle, which we saw very well, along with Changeable Hawk Eagle, Black Eagle and Black-thighed Falconet, to finish off our raptor extravaganza!

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