Monday, November 23, 2009

Borneo – Danum Valley

The lowland rainforest of Borneo is another place of wonder and beauty. There are fewer endemics in the lowlands than on the mountains and many of these species can also be seen on the Thai-Malay Peninsula. Nonetheless, there are some sites in Borneo that offer superb opportunities to view some of the most secretive species of the dark Sundaic lowland rainforests. One such place is Danum Valley, where most of the following photographs were taken.

It is very humbling to stand beneath the tall canopy of this rainforest. The canopy itself is like a sold green wall 50m above the ground and, in addition, massive emergent trees of the dipterocarp family (Greek: di – pteron – karpos = two-winged fruit) tower above the canopy, some reaching 70 or even 80m in height. Needless to say, little light reaches the forest floor. When you hear the pulsating sound of a hornbill’s wing beats, you can only crane your neck and hope that they will fly through a clearing.

There are a few endemics living high in the canopy and one of them is the peculiar Bornean Bristlehead. This species is hard to find and as a denizen of the tall canopy had never been photographed before I got this shot – it was published in 2002 in the Oriental Bird Club Bulletin 35: 75- 77. It is a poor shot, looking straight up and heavily backlit and there have since been better photos taken by others but at the time it was a great honour to be the first person to photograph a wild Bornean Bristlehead. The only reason I managed this shot at all was by being in the right place at the right time, on a high ridge that allowed me views into the canopy of the trees lower down the slope.

Out on a snag, another Bornean endemic, the tiny White-fronted Falconet, caches a dragonfly for later consumption. As you can tell this handsome falcon is not that much bigger than a dragonfly. They are amazing fliers though and I once saw a related species catch a swallow.

There is a great variety of fruit in the canopy and likewise a variety of fruit-eating birds. This the beautiful and shy Dark-throated Oriole, coming in to feed. Old World Orioles are among a large group of birds loosely related to crows (unlike New World orioles that are icterids along with New World blackbirds, cowbirds, oropendulas and caciques).

Many of the canopy species are green, which provides great camouflage. This is a male Red-throated Barbet (photo of a juvenile in the fruit-eaters series).

The aptly named leafbirds, are an Asian family of real birds – no, not leaves that look like birds! Like the Asian barbets, they are mostly green all over with any colour restricted to the head. This is a Lesser Green Leafbird.

The Asian Fairy Bluebird is another dramatic rainforest species whose spectacular rich colour against the dark background of the forest makes it seem like they are plugged into a power source! Genetic evidence suggests they are related to leafbirds, although rather different from most of that family in appearance.

On the blue-green note, here is a Chestnut-bellied Malkoha. Malkohas are large Old World cuckoos with a distinctive shape and very long tails. They are unusual among Old World cuckoos in that they are not brood-parasitic (brood parasites lay their eggs in other birds’ nests).

The Raffles Malkoha exhibits a rather different colour scheme. This is a female with a grayish head and a brown tail.

Speaking of long tails – not many exceed the male Asian Paradise Flycatcher! This male is a rufous morph but there is also a white morph (all white except for black head). Although called a flycatcher, this species does not belong to the flycatcher family. Like the Old World Orioles, they are more closely related to crows (remember that Birds of Paradise are crow-relatives too!).

Different colour scheme but the Black-naped Monarch is also related to the paradise flycatcher. This stunning male was worth waiting for near his nest.

The lowland rainforest is full of hornbills although they are surprisingly hard to see considering their enormous size. This is the magnificent Rhinoceros Hornbill, named for the hollow casque above the bill. It was always a great delight to see these magnificent creatures – I think my heart always skipped a beat when I heard their wing beats overhead.

High in the canopy on a dead branch, a pair of Great Slaty Woodpeckers are looking for a meal. At half a meter in length, they are as large as the Ivory-billed Woodpecker (but still smaller than the presumed-extinct Imperial Woodpecker).

Of a more “normal” size, the Banded Woodpecker is one of the many red and green woodpeckers in the genus Picus. This bird is feeding on ants on a dead palm frond.

Woodpeckers are remarkably diverse in Borneo. There are also woodpeckers in the Philippines but as one moves further east they start to drop out of the avifauna – there are none at all in Australasia! Amazing to think of a continent without woodpeckers, but fortunately for the parrots and other cavity nesters of Australia, eucalypts and some other Australasian trees are riddled with natural cavities. In Borneo, the beautiful Rufous Woodpecker is one of a few mostly red woodpeckers.

And dwarfed by the Great Slaty Woodpecker, at less than 10cm in length the tiny Rufous Piculet may not look a lot like the larger woodpeckers but that is what they are!

The honeyguides are related to woodpeckers. Most of the diversity in this family is found in Africa and their biggest claim to fame is that some species will lead mammals to bee-hives (like the Ratel or honey badger or even humans) and then get an easy meal after the mammals rip open the hive. In Asia there are only a few species of honeyguides and they are very secretive forest dwellers that many search for but few see. This is a female Malaysian Honeyguide.

You may think of kingfishers as water birds but in Asia and Australasia there are some kingfishers that a deep forest species and which feed on a variety of reptiles and amphibians, not necessarily associated with water. The spectacular Banded Kingfisher is one such species.

As is the Rufous-collared Kingfisher. I was elated to get a photo of this super shy denizen of the forest, although it is so dark you can barely see the bird!

The broadbills are a mostly Asian family of little forest jewels – always a highlight when you see one well. The Black-and-yellow Broadbill has a rather unusual colour combination - black, pink, yellow and blue bill! Wow!

The Dusky Broadbill may be among the least colourful of the Asian broadbills but still a fascinating species to watch – and what a bill!

There are many bulbuls in the forest too, like this Finch’s Bulbul.

And Asia is of course famous for the monstrously large and diverse babbler family (although recent genetic studies seem to be splitting this family up somewhat). Here a Chestnut-rumped Babbler slinks around.

Related to robins, the beautiful Rufous-tailed Shama is one of those species that I had great difficulty connecting with on the Thai-Malay peninsula but seemed to find them much more easily at Danum Valley.

The sunbirds are a fantastic family of small nectar eaters. This is a male Crimson Sunbird. Knocks your socks off every time really!

Sunbirds build closed nests that dangle from a thin branch or vine that barely supports their weight. This is presumed to be an anti-predator devise and may limit access by snakes and other nest predators. Some other Asian tropical birds such as the broadbills also build dangling nests. This is a male Olive-backed Sunbird feeding young.

And why not finish with an endemic… this is a Yellow-rumped Flowerpecker feeding on small fruit. The flowerpeckers are nectar and fruit eaters related to sunbirds. They also come in a dazzling array of colours.

More to come!

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