Explorations of an Ecologist: Borneo 2018: Part 7 (Kinabatangan River, Gomantong Caves)

Part 1: Fly to Borneo, Kota Kinabalu (September 30 - October 2, 2018)
Part 2: Kota Kinabalu to Mount Kinabalu (October 3, 2018)
Part 3: Full day at Mount Kinabalu (October 4, 2018)
Part 4: Mount Kinabalu to Sepilok (October 5, 2018)
Part 5: Sepilok (October 6, 2018)
Part 6: Kinabatangan River (October 6-7, 2018)
Part 7: Kinabatangan River, Gomantong Caves (October 7-8, 2018)
Part 8: Tabin Wildlife Reserve (October 8-9, 2018)
Part 9: Tabin Wildlife Reserve (October 9-10, 2018)
Part 10: Danum Valley (October 11-12, 2018)
Part 11: Danum Valley (October 13-14, 2018)

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October 7, 2019 (continued)

We all enjoyed a two hour break before reconvening for our late afternoon boat ride. I mostly relaxed during the break, though the birds around the cabins kept me alert. A new one for me was a Chestnut-necklaced Partridge vocalizing from the understorey in the dense forest surrounding the lodge.

We headed downriver for our evening boat cruise, eager to explore a new area. Along a small section of limestone lining the river a small colony of Plume-toed Swifts were present.

Plume-toed Swiftlets - Kinabatangan River, Sabah, Malaysia

Birding was steady with many great sightings - several White-tailed Sea-Eagles, two Lesser Fish-Eagles, a flock of Little Green Pigeons and Common Hill Mynas to name a few.

White-tailed Sea-Eagle - Kinabatangan River, Sabah, Malaysia

A pair of dark hornbills took off from a riverside perch and flew away from the boat, but something about them seemed different. Wreathed Hornbill!! This was a new one for the group and by far the best looks I have ever had of this species (my previous sighting was a brief flyover at the Poring Hot Springs in 2017).

Wreathed Hornbill - Kinabatangan River, Sabah, Malaysia

Small groups of primates were commonly noted as we traveled and included Pig-tailed Macaques, Long-tailed Macaques, Silvered Leaf Monkey and Proboscis Monkey. Interestingly, one of the Silvered Leaf Monkeys was of the pale rufous morph, a genetic curiosity that seems to occur with relative frequency in the forests along the Kinabatangan River. While appearing superficially similar to the Maroon Leaf Monkey, the lack of a black face and paler fur color easily identify this individual as a Silvered Leaf Monkey.

Silvered Leaf Monkey (pale morph) - Kinabatangan River, Sabah, Malaysia

We spotted a few more groups of proboscis monkeys as we traveled, many of them settling in for the night along the riverbanks. Probosics Monkeys congregate in trees alongside the rivers at dusk to limit their exposure to predators. Generally, the biggest terrestrial predator of Proboscis Monkey is the Clouded Leopard so by resting at the river's edge and facing the forest, they can increase their odds of detecting a Clouded Leopard ahead of time. They just need to make sure that they are located high enough up in the trees to prevent the chance of a surprise attack from a Saltwater Crocodile. Life isn't easy.

Proboscis Monkeys - Kinabatangan River, Sabah, Malaysia

We returned to the lodge to eat dinner and by 8:00 PM had reassembled at the docks for an hour-long night cruise. This is one of my favorite activities in the Bornean lowlands and while Reticulated Pythons remained out of sight yet again we still had a blast. Several Buffy Fish-Owls are a good bet to be found along the river and today was no different. This one turned it's head away from me just a second too early.

Buff Fish-Owl - Kinabatangan River, Sabah, Malaysia

While Saltwater Crocodiles appear uncommon at best during the day, in the evenings they really come out of the woodwork. Or rather, they become much more obvious due to the orange eyeshine they produce when hit with a light. We saw very few Saltwater Crocodiles during our stay at the Kinabatangan River this year - maybe four in total, compared to over twenty in 2017. The river appeared to be flowing with greater velocity this year - perhaps the crocodiles were hanging out in the calmer tributaries.

Saltwater Crocodile - Kinabatangan River, Sabah, Malaysia

Not a Reticulated Python, but a reptile at least! This is a sleepy Asian Water Monitor.

Asian Water Monitor - Kinabatangan River, Sabah, Malaysia

Part of the fun of spotlighting a river at night is the possibility of coming across birds roosting in the shoreline vegetation. This evening we spotted a few Stork-billed Kingfishers, a small group of Black-and-red Broadbills, a Blue-eared Kingfisher and some Oriental Magpie-Robins including one with a deformed bill.

Stork-billed Kingfisher - Kinabatangan River, Sabah, Malaysia

Black-and-red Broadbills - Kinabatangan River, Sabah, Malaysia

Oriental Magpie-Robin - Kinabatangan River, Sabah, Malaysia

Common Palm Civets are active mostly at night and love feeding on certain species of oily palm fruits.

Common Palm Civet - Kinabatangan River, Sabah, Malaysia

October 8, 2019

We awoke to a steamy morning in the Bornean lowlands. I made sure that I was up before dawn to listen to the forest come alive as it was our last morning along the Kinabatangan River. The Chestnut-necklaced Partridge was calling again from somewhere unseen while a bonus Crested Goshawk also appeared.

We said our goodbyes to the staff and boarded the boats for the last time. We made the short ride over to the docks at Sukau, transferred to our waiting bus, and hit the road.

Our last six nights in the Bornean lowlands would be split between two fantastic lodges situated at the edges of relatively large reserves. First up would be the Tabin Wildlife Reserve, followed by the Borneo Rainforest Lodge in the Danum Valley. To break up the drive to Tabin we made a stop at the Gomantong Caves to view the bats, swiftlets, and whatever else we could find.

Gomantong Caves, Sabah, Malaysia

Within the immediate vicinity of the caves a large swath of forest had been protected, preventing the land from the insatiable saws of the logging industry and the resulting oil palm plantations that have taken up so much of southeast Asia. Bornean Orangutans could be found in this forest, and indeed we viewed several old "nests" created by individuals each evening to sleep in, but no orangutans.

We followed a boardwalk through a section of forest that eventually opened up near the main cave entrance. A few small flocks of birds passed through that included Sooty-capped and Chestnut-winged Babbler. But the babblers were quickly forgotten when our first gliding lizard (Draco) was spotted! The identification of these species is a bit tricky and I am not sure which one this is. We watched for a few minutes but it refused to glide for us!

Draco sp. - Gomantong Caves, Sabah, Malaysia

The sights and especially the smells within the cave were something to behold. High-pitched, twittering calls indicated to us that tens of thousands of bats and swiftlets were present, and certain walls of the cave were covered in small dark spots, each representing a bat hanging from the ceiling. The acidic smell took a few minutes to get used to while millions of cochroaches scuttled around, ensuring that this was not the place for the faint of heart. The sheer biomass in these caves is incredible, especially when it comes to cochroaches. The ever growing pile of nutrient-rich guano was several meters high across the floor of the cave.

Unidentified bat - Gomantong Caves, Sabah, Malaysia

We were all a little relieved to exit the cave and breath fresh air again. A unique experience, to say the least! One day I would love to visit the cave at dusk when the bats leave and the swifts come back in, since often several raptors (including Bat Hawks) gather near the cave entrance to feast.

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Tuesday, 16 July 2019

Borneo 2018: Part 7 (Kinabatangan River, Gomantong Caves)

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